,,the ,,organisation ,,of ,,thought ,,the ,,organisation ,,of ,,thought ,,educational ,,and ,,scientific ,,by ,a4 ,n4 ,,whitehead1 ,sc4,d41 ,f4,r4,s4 ,,fellow ,,of ,,trinity ,,college1 ,,cambridge1 ,,and ,,professor ,,of ,,applied ,,mathematics ,,at ,,the ,,imperial ,,college ,,of ,,science ,,and ,,technology ,,london ,,williams ,,and ,,norgate #ad ,,henrietta ,,street1 ,,covent ,,garden1 ,w4,c4#b #aiag ,the rights of translation are reserved ,,preface ,,the discourses included in this volume have been delivered as addresses on various occasions which are duly noted2 the only exception is ,the ,anatomy of ,some ,scientific ,ideas1 which is now published for the first time4 ,these discourses fall into two sections1 the first five chapters deal with education1 and the remaining three embody discussions on certain points arising in the philosophy of science4 ,but a common line of reflection extends through the whole1 and the two sections influence each other4 ,i have left in each chapter the reference to the particular occasion of its first production1 and ,i have not sought for a verbal consistency covering perplexity4 ,but the various parts of the book were in fact composed with express reference to each other1 so as to form one whole4 ,i have to thank the ,syndics of the ,cambridge ,university ,press for permission to republish the contents of ,chapter ,v4 ,imperial ,college of ,science and ,technology1 ,april #aiag4 ,,table ,,of ,,contents ,,chap4 ,,page ,,preface v ,i4 ,,the ,,aims ,,of ,,education--,a ,,plea ,,for ,,reform #a 7,presidential ,address to the ,mathematical ,association1 ,january1 #aiaf47 ,,ii4 ,,technical ,,education ,,and ,,its ,,relation ,,to ,,science ,,and ,,literature #bi 7,presidential ,address to the ,mathematical ,association1 ,january1 #aiag47 ,,iii4 ,a ,,polytechnic ,,in ,,war-,,time #eh 7,address at the ,prize ,distribution1 ,borough ,polytechnic ,institute1 ,southwark1 ,february1 #aiag47 ,,iv4 ,,the ,,mathematical ,,curriculum #fi 7,presidential ,address to the ,london ,branch of the ,mathematical ,association1 #aiab47 ,v4 ,,the ,,principles ,,of ,,mathematics ,,in ,,relation ,,to ,,elementary ,,teaching #ib 7,paper read in the ,educational ,section of the ,international ,congress of ,mathematicians1 ,cambridge1 #aiab47 ,,vi4 ,,the ,,organisation ,,of ,,thought #aje 7,presidential ,address to ,section ,a1 ,british ,association1 ,newcastle1 #aiaf2 also read subsequently before the ,aristotelian ,society47 ,,vii4 ,,the ,,anatomy ,,of ,,some ,,scientific ,,ideas #acd ,,viii4 ,,space1 ,,time1 ,,and ,,relativity #aia 7,paper read to ,section ,a at the ,manchester ,meeting of ,section ,a1 #aiae2 also1 with the appended ,commentary1 read subsequently before the ,aristotelian ,society47 ,,organisation ,,of ,,thought ,,chapter ,i ,,the ,,aims ,,of ,,education--,a ,,plea ,,for ,,reform 7,presidential ,address to the ,mathematical ,association1 ,january1 #aiaf7 ,,when ,i had the honour of being made ,president of the ,mathematical ,association1 ,i did not foresee the unusual responsibility which it entailed4 ,it was my intention to take as the theme of a presidential address the consideration of some aspect of those special subjects to which my own researches have principally been directed4 ,events have forced me to abandon that intention4 ,it is useless to discuss abstract questions in the midst of dominant practical preoccupation4 ,we cannot disregard the present crisis in ,european civilisation4 ,it affects every function of life4 ,in the harder struggle for existence which lies before the nation1 all departments of national effort will be reviewed for judgment4 ,the mere necessity for economy in resources will provoke this reformation4 ,we are concerned with education4 ,this ,association1 so rich in its membership of educationalists1 with the conception of reform as the very reason of its being1 is among those bodies which must take the lead in guiding that educational reconstruction which by a sociological law follows every social revolution4 ,we do not want impracticable ideals1 only to be realised beyond the clouds in ,some wild1 weird clime1 ,out of ,space1 and out of ,time4 ,we require to know what is possible now in ,england1 a nation conscious of its high achievements1 and of great failures1 shaken to its foundations1 distrustful of the old ways1 and dreading fantastic novelties4 ,i will take my courage in both hands1 and put before you an outline of educational principles4 ,what ,i am going to say is of course entirely without your authority1 and does not pledge or prejudge any action of the ,association4 ,we are primarily concerned only with the intellectual side of education1 and1 as mathematicians1 are naturally concerned to illustrate details more particularly by reference to mathematics4 ,thus much to explain deliberate omissions in what follows4 ,consider now the general and special education of two types of boys1 namely those in secondary schools who in after life must form the professional and directing classes in commerce1 industry1 and public administration1 and again those in junior technical schools and later in advanced continuation classes1 who are going to form the class of skilled artisans and foremen of workshops4 ,these two sets compose the educated strength of the nation4 ,we must form no ideals which include less than these entire classes within their scope4 ,what ,i shall say1 will in phraseology apply more directly to the secondary schools1 but with unessential changes it will apply equally to the other group4 ,what is the first commandment to be obeyed in any educational scheme8 ,it is this3 ,do not teach too many subjects4 ,the second command is this3 ,what you teach1 teach thoroughly4 ,the devil in the scholastic world has assumed the form of a general education consisting of scraps of a large number of disconnected subjects2 and1 with the artfulness of the serpent1 he has entrenched himself behind the matriculation examination of the ,university of ,london1 with a wire entanglement formed by the ,oxford and ,cambridge schools' examination4 ,culture is activity of thought1 and receptiveness to beauty1 and humane feeling4 ,scraps of information have nothing to do with it4 ,a merely well-informed man is the most useless bore on ,god's earth4 ,what we should aim at producing is men who possess both culture and expert knowledge in some special direction4 ,their expert knowledge will give them the ground to start from1 and their culture will lead them as deep as philosophy and as high as art4 ,we have to remember that the valuable intellectual development is self-development1 and that it mostly takes place between the ages of sixteen and thirty4 ,as to training1 the most important part is given by mothers before the age of twelve4 ,a saying due to ,archbishop ,temple illustrates my meaning4 ,surprise was expressed at the success in after-life of a man1 who as a boy at ,rugby had been somewhat undistinguished4 ,he answered1 ,it is not what they are at eighteen1 it is what they become afterwards that matters4 ,in training a child to activity of thought1 above all things we must beware of what ,i will call inert ideas--that is to say1 ideas that are merely received into the mind without being utilised1 or tested1 or thrown into fresh combinations4 ,in the history of education1 the most striking phenomenon is that schools of learning1 which at one epoch are alive with a ferment of genius1 in a succeeding generation exhibit merely pedantry and routine4 ,the reason is1 that they are overladen with inert ideas4 ,education with inert ideas is not only useless3 it is1 above all things1 harmful--,corruptio optimi1 pessima4 ,except at rare intervals of intellectual ferment1 education in the past has been radically infected with inert ideas4 ,that is the reason why uneducated clever women1 who have seen much of the world1 are in middle life so much the most cultured part of the community4 ,they have been saved from this horrible burden of inert ideas4 ,every intellectual revolution which has ever stirred humanity into greatness has been a passionate protest against inert ideas4 ,then1 alas1 with pathetic ignorance of human psychology1 it has proceeded by some educational scheme to bind humanity afresh with inert ideas of its own fashioning4 ,let us now ask how in our system of education we are to guard against this mental dry rot4 ,we recur to our two educational commandments1 ,do not teach too many subjects1 and again1 ,what you teach1 teach thoroughly4 ,the result of teaching small parts of a large number of subjects is the passive reception of disconnected ideas1 not illumined with any spark of vitality4 ,let the main ideas which are introduced into a child's education be few and important1 and let them be thrown into every combination possible4 ,the child should make them his own1 and should understand their application here and now in the circumstances of his actual life4 ,from the very beginning of his education1 the child should experience the joy of discovery4 ,the discovery which he has to make1 is that general ideas give an understanding of that stream of events which pours through his life1 which is his life4 ,by understanding ,i mean more than a mere logical analysis1 though that is included4 ,i mean understanding in the sense in which it is used in the ,french proverb1 ,to understand all1 is to forgive all4 ,pedants sneer at an education which is useful4 ,but if education is not useful1 what is it8 ,is it a talent1 to be hidden away in a napkin8 ,of course1 education should be useful1 whatever your aim in life4 ,it was useful to ,saint ,augustine and it was useful to ,napoleon4 ,it is useful1 because understanding is useful4 ,i pass lightly over that understanding which should be given by the literary side of education4 ,it is not peculiarly the function of this ,association to consider it4 ,nor do ,i wish to be supposed to pronounce on the relative merits of a classical or a modern curriculum4 ,i would only remark that the understanding which we want is an understanding of an insistent present4 ,the only use of a knowledge of the past is to equip us for the present4 ,no more deadly harm can be done to young minds than by depreciation of the present4 ,the present contains all that there is4 ,it is holy ground2 for it is the past1 and it is the future4 ,at the same time it must be observed that an age is no less past if it existed two hundred years ago than if it existed two thousand years ago4 ,do not be deceived by the pedantry of dates4 ,the ages of ,shakespeare and of ,molire are no less past than are the ages of ,sophocles and of ,virgil4 ,the communion of saints is a great and inspiring assemblage1 but it has only one possible hall of meeting1 and that is1 the present2 and the mere lapse of time through which any particular group of saints must travel to reach that meeting-place1 makes very little difference4 ,passing now to the scientific and logical side of education1 we remember that here also ideas which are not utilised are positively harmful4 ,by utilising an idea1 ,i mean relating it to that stream1 compounded of sense perceptions1 feelings1 hopes1 desires1 and of mental activities relating thought to thought1 which forms our life4 ,i can imagine a set of beings which might fortify their souls by passively reviewing disconnected ideas4 ,humanity is not built that way--except perhaps some editors of newspapers4 ,in scientific training1 the first thing to do with an idea is to prove it4 ,but allow me for one moment to extend the meaning of prove2 ,i mean--to prove its worth4 ,now an idea is not worth much unless the propositions in which it is embodied are true4 ,accordingly an essential part of the proof of an idea is the proof1 either by experiment or by logic1 of the truth of the propositions4 ,but it is not essential that this proof of the truth should constitute the first introduction to the idea4 ,after all1 its assertion by the authority of respectable teachers is sufficient evidence to begin with4 ,in our first contact with a set of propositions1 we commence by appreciating their importance4 ,that is what we all do in after-life4 ,we do not attempt1 in the strict sense1 to prove or to disprove anything1 unless its importance makes it worthy of that honour4 ,these two processes of proof1 in the narrow sense1 and of appreciation do not require a rigid separation in time4 ,both can be proceeded with nearly concurrently4 ,but in so far as either process must have the priority1 it should be that of appreciation by use4 ,furthermore1 we should not endeavour to use propositions in isolation4 ,emphatically ,i do not mean1 a neat little set of experiments to illustrate ,proposition ,i and then the proof of ,proposition ,i1 a neat little set of experiments to illustrate ,proposition ,,ii and then the proof of ,proposition ,,ii1 and so on to the end of the book4 ,nothing could be more boring4 ,inter-related truths are utilised en bloc1 and the various propositions are employed in any order1 and with any reiteration4 ,choose some important applications of your theoretical subject2 and study them concurrently with the systematic theoretical exposition4 ,keep the theoretical exposition short and simple1 but let it be strict and rigid so far as it goes4 ,it should not be too long for it easily to be known with thoroughness and accuracy4 ,the consequences of a plethora of half-digested theoretical knowledge are deplorable4 ,also the theory should not be muddled up with the practice4 ,the child should have no doubt when it is proving and when it is utilising4 ,my point is that what is proved should be utilised1 and that what is utilised should--so far as is practicable--be proved4 ,i am far from asserting that proof and utilisation are the same thing4 ,at this point of my discourse1 ,i can most directly carry forward my argument in the outward form of a digression4 ,we are only just realising that the art and science of education require a genius and a study of their own2 and that this genius and this science are more than a bare knowledge of some branch of science or of literature4 ,this truth was partially perceived in the past generation2 and headmasters1 somewhat crudely1 were apt to supersede learning in their colleagues by requiring left-hand bowling and a taste for football4 ,but culture is more than cricket1 and more than football1 and more than extent of knowledge4 ,education is the acquisition of the art of the utilisation of knowledge4 ,this is an art very difficult to impart4 ,whenever a text-book is written of real educational worth1 you may be quite certain that some reviewer will say that it will be difficult to teach from it4 ,of course it will be difficult to teach from it4 ,if it were easy1 the book ought to be burned2 for it cannot be educational4 ,in education1 as elsewhere1 the broad primrose path leads to a nasty place4 ,this evil path is represented by a book or a set of lectures which will practically enable the student to learn by heart all the questions likely to be asked at the next external examination4 ,and ,i may say in passing that no educational system is possible unless every question directly asked of a pupil at any examination is either framed or modified by the actual teacher of that pupil in that subject4 ,the external assessor may report on the curriculum or on the performance of the pupils1 but never should be allowed to ask the pupil a question which has not been strictly supervised by the actual teacher1 or at least inspired by a long conference with him4 ,there are a few exceptions to this rule1 but they are exceptions1 and could easily be allowed for under the general rule4 ,we now return to my previous point1 that theoretical ideas should always find important applications within the pupil's curriculum4 ,this is not an easy doctrine to apply1 but a very hard one4 ,it contains within itself the problem of keeping knowledge alive1 of preventing it from becoming inert1 which is the central problem of all education4 ,the best procedure will depend on several factors1 none of which can be neglected1 namely1 the genius of the teacher1 the intellectual type of the pupils1 their prospects in life1 the opportunities offered by the immediate surroundings of the school1 and allied factors of this sort4 ,it is for this reason that the uniform external examination is so deadly4 ,we do not denounce it because we are cranks1 and like denouncing established things4 ,we are not so childish4 ,also1 of course1 such examinations have their use in testing slackness4 ,our reason of dislike is very definite and very practical4 ,it kills the best part of culture4 ,when you analyse in the light of experience the central task of education1 you find that its successful accomplishment depends on a delicate adjustment of many variable factors4 ,the reason is that we are dealing with human minds1 and not with dead matter4 ,the evocation of curiosity1 of judgment1 of the power of mastering a complicated tangle of circumstances1 the use of theory in giving foresight in special cases--all these powers are not to be imparted by a set rule embodied in one schedule of examination subjects4 ,i appeal to you1 as practical teachers4 ,with good discipline1 it is always possible to pump into the minds of a class a certain quantity of inert knowledge4 ,you take a text-book and make them learn it4 ,so far1 so good4 ,the child then knows how to solve a quadratic equation4 ,but what is the point of teaching a child to solve a quadratic equation8 ,there is a traditional answer to this question4 ,it runs thus3 ,the mind is an instrument1 you first sharpen it1 and then use it2 the acquisition of the power of solving a quadratic equation is part of the process of sharpening the mind4 ,now there is just enough truth in this answer to have made it live through the ages4 ,but for all its half-truth1 it embodies a radical error which bids fair to stifle the genius of the modern world4 ,i do not know who was first responsible for this analogy of the mind to a dead instrument4 ,for aught ,i know1 it may have been one of the seven wise men of ,greece1 or a committee of the whole lot of them4 ,whoever was the originator1 there can be no doubt of the authority which it has acquired by the continuous approval which it has received from eminent persons4 ,but whatever its weight of authority1 whatever the high approval which it can quote1 ,i have no hesitation in denouncing it as one of the most fatal1 erroneous1 and dangerous conceptions ever introduced into the theory of education4 ,the mind is never passive2 it is a perpetual activity1 delicate1 receptive1 responsive to stimulus4 ,you cannot postpone its life until you have sharpened it4 ,whatever interest attaches to your subject-matter1 must be evoked here and now2 whatever powers you are strengthening in the pupil1 must be exercised here and now2 whatever possibilities of mental life your teaching should impart1 must be exhibited here and now4 ,that is the golden rule of education1 and a very difficult rule to follow4 ,the difficulty is just this3 the apprehension of general ideas1 intellectual habits of mind1 and pleasurable interest in mental achievement can be evoked by no form of words1 however accurately adjusted4 ,all practical teachers know that education is a patient process of the mastery of details1 minute by minute1 hour by hour1 day by day4 ,there is no royal road to learning through an airy path of brilliant generalisations4 ,there is a proverb about the difficulty of seeing the wood because of the trees4 ,that difficulty is exactly the point which ,i am enforcing4 ,the problem of education is to make the pupil see the wood by means of the trees4 ,the solution which ,i am urging1 is to eradicate the fatal disconnection of subjects which kills the vitality of our modern curriculum4 ,there is only one subject-matter for education1 and that is ,life in all its manifestations4 ,instead of this single unity1 we offer children--,algebra1 from which nothing follows2 ,geometry1 from which nothing follows2 ,science1 from which nothing follows2 ,history1 from which nothing follows2 a ,couple of ,languages1 never mastered2 and lastly1 most dreary of all1 ,literature1 represented by plays of ,shakespeare1 with philological notes and short analyses of plot and character to be in substance committed to memory4 ,can such a list be said to represent ,life1 as it is known in the midst of the living of it8 ,the best that can be said of it is1 that it is a rapid table of contents which a deity might run over in his mind while he was thinking of creating a world1 and had not yet determined how to put it together4 ,let us now return to quadratic equations4 ,we still have on hand the unanswered question4 ,why should children be taught their solution8 ,unless quadratic equations fit into a connected curriculum1 of course there is no reason to teach anything about them4 ,furthermore1 extensive as should be the place of mathematics in a complete culture1 ,i am a little doubtful whether for many types of boys algebraic solutions of quadratic equations do not lie on the specialist side of mathematics4 ,i may here remind you that as yet ,i have not said anything of the psychology or the content of the specialism1 which is so necessary a part of an ideal education4 ,but all that is an evasion of our real question1 and ,i merely state it in order to avoid being misunderstood in my answer4 ,quadratic equations are part of algebra1 and algebra is the intellectual instrument which has been created for rendering clear the quantitative aspects of the world4 ,there is no getting out of it4 ,through and through the world is infected with quantity4 ,to talk sense1 is to talk in quantities4 ,it is no use saying that the nation is large1--,how large8 ,it is no use saying that radium is scarce1--,how scarce8 ,you cannot evade quantity4 ,you may fly to poetry and to music1 and quantity and number will face you in your rhythms and your octaves4 ,elegant intellects which despise the theory of quantity1 are but half developed4 ,they are more to be pitied than blamed4 ,the scraps of gibberish1 which in their school-days were taught to them in the name of algebra1 deserve some contempt4 ,this question of the degeneration of algebra into gibberish1 both in word and in fact1 affords a pathetic instance of the uselessness of reforming educational schedules without a clear conception of the attributes which you wish to evoke in the living minds of the children4 ,a few years ago there was an outcry that school algebra was in need of reform1 but there was a general agreement that graphs would put everything right4 ,so all sorts of things were extruded1 and graphs were introduced4 ,so far as ,i can see1 with no sort of idea behind them1 but just graphs4 ,now every examination paper has one or two questions on graphs4 ,personally1 ,i am an enthusiastic adherent of graphs4 ,but ,i wonder whether as yet we have gained very much4 ,you cannot put life into any schedule of general education unless you succeed in exhibiting its relation to some essential characteristic of all intelligent or emotional perception4 ,it is a hard saying1 but it is true2 and ,i do not see how to make it any easier4 ,in making these little formal alterations you are beaten by the very nature of things4 ,you are pitted against too skilful an adversary1 who will see to it that the pea is always under the other thimble4 ,reformation must begin at the other end4 ,first1 you must make up your mind as to those quantitative aspects of the world which are simple enough to be introduced into general education2 then a schedule of algebra should be framed which will about find its exemplification in these applications4 ,we need not fear for our pet graphs1 they will be there in plenty when we once begin to treat algebra as a serious means of studying the world4 ,some of the simplest applications will be found in the quantities which occur in the simplest study of society4 ,the curves of history are more vivid and more informing than the dry catalogues of names and dates which comprise the greater part of that arid school study4 ,what purpose is effected by a catalogue of undistinguished kings and queens8 ,tom1 ,dick1 or ,harry1 they are all dead4 ,general resurrections are failures1 and are better postponed4 ,the quantitative flux of the forces of modern society are capable of very simple exhibition4 ,meanwhile1 the idea of the variable1 of the function1 of rate of change1 of equations and their solution1 of elimination1 are being studied as an abstract science for their own sake4 ,not1 of course1 in the pompous phrases with which ,i am alluding to them here1 but with that iteration of simple special cases proper to teaching4 ,if this course be followed1 the route from ,chaucer to the ,black ,death1 from the ,black ,death to modern ,labour troubles1 will connect the tales of the medival pilgrims with the abstract science of algebra1 both yielding diverse aspects of that single theme1 ,life4 ,i know what most of you are thinking at this point4 ,it is that the exact course which ,i have sketched out is not the particular one which you would have chosen1 or even see how to work4 ,i quite agree4 ,i am not claiming that ,i could do it myself4 ,but your objection is the precise reason why a common external examination system is fatal to education4 ,the process of exhibiting the applications of knowledge must1 for its success1 essentially depend on the character of the pupils and the genius of the teacher4 ,of course ,i have left out the easiest applications with which most of us are more at home4 ,i mean the quantitative sides of sciences1 such as mechanics and physics4 ,my meaning can be illustrated by looking more closely into a special case of this type of application4 ,in my rough catalogue of the sort of subjects which should form the schedule for algebra1 ,i mentioned ,elimination4 ,it was not put there by accident1 for it covers a very important body of thought4 ,in the first place1 there is the abstract process of algebraic elimination for suitable simple cases4 ,the pupil acquires a firm grasp of this by the process1 inevitable in education1 of working an adequate number of examples4 ,again1 there are the graphical solutions of the same problem4 ,then we consider the significance in the external world4 ,we consider the velocity1 time1 space1 acceleration diagrams4 ,we take uniform acceleration2 we eliminate t between v u t1 and s ut t#b1 and eliminate s between v#b u#b #bs1 and s ut t#b4 ,then we remember that constant acceleration is a very special case1 and we consider graphical solutions or empirically given variations of v or of 4 ,in preference1 we use those empirical formul which occur in the pupil's experimental work4 ,we compare the strong and weak points of the algebraic and graphical solutions4 ,again1 in the same connection we plot the statistics of social phenomena against the time4 ,we then eliminate the time between suitable pairs4 ,we can speculate how far we have exhibited a real casual connection1 or how far a mere temporal coincidence4 ,we notice that we might have plotted against the time one set of statistics for one country and another set for another country1 and thus1 with suitable choice of subjects1 have obtained graphs which certainly exhibited mere coincidence4 ,also other graphs exhibit obvious casual connections4 ,we wonder how to discriminate4 ,and so are drawn on as far as we will4 ,but in considering this description1 ,i must beg you to remember what ,i have been insisting on above4 ,in the first place1 one train of thought will not suit all groups of children4 ,for example1 ,i should expect that artisan children will want something more concrete and1 in a sense1 swifter than ,i have set down here4 ,perhaps ,i am wrong1 but that is what ,i should guess4 ,in the second place1 ,i am not contemplating one beautiful lecture stimulating1 once and for all1 an admiring class4 ,that is not the way in which education proceeds4 ,no2 all the time the pupils are hard at work solving examples1 drawing graphs1 and making experiments1 until they have a thorough hold on the whole subject4 ,i am describing the interspersed explanations1 the directions which should be given to their thoughts4 ,the pupils have got to be made to feel that they are studying something1 and are not merely executing intellectual minuets4 ,in this connection the excellence of some of the most recent text-books on elementary algebra emanating from members of this ,association1 should create an epoch in the teaching of the subject4 ,finally1 if you are teaching pupils for some general examination1 the problem of sound teaching is greatly complicated4 ,have you ever noticed the zig-zag moulding round a ,norman arch8 ,the ancient work is beautiful1 the modern work is hideous4 ,the reason is1 that the modern work is done to exact measure1 the ancient work is varied according to the idiosyncrasy of the workman4 ,here it is crowded1 and there it is expanded4 ,now the essence of getting pupils through examinations is to give equal weight to all parts of the schedule4 ,but mankind is naturally specialist4 ,one man sees a whole subject1 where another can find only a few detached examples4 ,i know that it seems contradictory to allow for specialism in a curriculum especially designed for a broad culture4 ,without contradictions the world would be simpler1 and perhaps duller4 ,but ,i am certain that in education wherever you exclude specialism you destroy life4 ,we now come to the other great branch of a general mathematical education1 namely ,geometry4 ,the same principles apply4 ,the theoretical part should be clear-cut1 rigid1 short1 and important4 ,every proposition not absolutely necessary to exhibit the main connection of ideas should be cut out1 but the great fundamental ideas should be all there4 ,no omission of concepts1 such as those of ,similarity and ,proportion4 ,we must remember that1 owing to the aid rendered by the visual presence of a figure1 ,geometry is a field of unequalled excellence for the exercise of the deductive faculties of reasoning4 ,then1 of course1 there follows ,geometrical ,drawing1 with its training for the hand and eye4 ,but1 like ,algebra1 ,geometry and ,geometrical ,drawing must be extended beyond the mere circle of geometrical ideas4 ,in an industrial neighbourhood1 machinery and workshop practice form the appropriate extension4 ,for example1 in the ,london ,polytechnics this has been achieved with conspicuous success4 ,for many secondary schools ,i suggest that surveying and maps are the natural applications4 ,in particular1 plane-table surveying should lead pupils to a vivid apprehension of the immediate application of geometric truths4 ,simple drawing apparatus1 a surveyor's chain1 and a surveyor's compass1 should enable the pupils to rise from the survey and mensuration of a field to the construction of the map of a small district4 ,the best education is to be found in gaining the utmost information from the simplest apparatus4 ,the provision of elaborate instruments is greatly to be deprecated4 ,to have constructed the map of a small district1 to have considered its roads1 its contours1 its geology1 its climate1 its relation to other districts1 the effects on the status of its inhabitants1 will teach more history and geography than any knowledge of ,perkin ,warbeck or of ,behren's ,straits4 ,i mean not a nebulous lecture on the subject1 but a serious investigation in which the real facts are definitely ascertained by the aid of accurate theoretical knowledge4 ,a typical mathematical problem should be3 ,survey such and such a field1 draw a plan of it to such and such a scale1 and find the area4 ,it would be quite a good procedure to impart the necessary geometrical propositions without their proofs4 ,then1 concurrently in the same term1 the proofs of the propositions would be learnt while the survey was being made4 ,fortunately1 the specialist side of education presents an easier problem than does the provision of a general culture4 ,for this there are many reasons4 ,one is that many of the principles of procedure to be observed are the same in both cases1 and it is unnecessary to recapitulate4 ,another reason is that specialist training takes place--or should take place--at a more advanced stage of the pupil's course1 and thus there is easier material to work upon4 ,but undoubtedly the chief reason is that the specialist study is normally a study of peculiar interest to the student4 ,he is studying it because1 for some reason1 he wants to know it4 ,this makes all the difference4 ,the general culture is designed to foster an activity of mind2 the specialist course utilises this activity4 ,but it does not do to lay too much stress on these neat antitheses4 ,as we have already seen1 in the general course foci of special interest will arise2 and similarly in the special study1 the external connections of the subject drag thought outwards4 ,again1 there is not one course of study which merely gives general culture1 and another which gives special knowledge4 ,the subjects pursued for the sake of a general education are special subjects specially studied2 and1 on the other hand1 one of the ways of encouraging general mental activity is to foster a special devotion4 ,you may not divide the seamless coat of learning4 ,what education has to impart is an intimate sense for the power of ideas1 for the beauty of ideas1 and for the structure of ideas1 together with a particular body of knowledge which has peculiar reference to the life of the being possessing it4 ,the appreciation of the structure of ideas is that side of a cultured mind which can only grow under the influence of a special study4 ,i mean that eye for the whole chess-board1 for the bearing of one set of ideas on another4 ,nothing but a special study can give any appreciation for the exact formulation of general ideas1 for their relations when formulated1 for their service in the comprehension of life4 ,a mind so disciplined should be both more abstract and more concrete4 ,it has been trained in the comprehension of abstract thought and in the analysis of facts4 ,finally1 there should grow the most austere of all mental qualities2 ,i mean the sense for style4 ,it is an sthetic sense1 based on admiration for the direct attainment of a foreseen end1 simply and without waste4 ,style in art1 style in literature1 style in science1 style in logic1 style in practical execution have fundamentally the same sthetic qualities1 namely1 attainment and restraint4 ,the love of a subject in itself and for itself1 where it is not the sleepy pleasure of pacing a mental quarter-deck1 is the love of style as manifested in that study4 ,here we are brought back to the position from which we started1 the utility of education4 ,style1 in its finest sense1 is the last acquirement of the educated mind2 it is also the most useful4 ,it pervades the whole being4 ,the administrator with a sense for style1 hates waste2 the engineer with a sense for style1 economises his material2 the artisan with a sense for style1 prefers good work4 ,style is the ultimate morality of mind4 ,but above style1 and above knowledge1 there is something1 a vague shape like fate above the ,greek gods4 ,that something is ,power4 ,style is the fashioning of power1 the restraining of power4 ,but1 after all1 the power of attainment of the desired end is fundamental4 ,the first thing is to get there4 ,do not bother about your style1 but solve your problem1 justify the ways of ,god to man1 administer your province1 or do whatever else is set before you4 ,where1 then1 does style help8 ,in this1 with style the end is attained without side issues1 without raising undesirable inflammations4 ,with style you attain your end and nothing but your end4 ,with style the effect of your activity is calculable1 and foresight is the last gift of gods to men4 ,with style your power is increased1 for your mind is not distracted with irrelevancies1 and you are more likely to attain your object4 ,now style is the exclusive privilege of the expert4 ,whoever heard of the style of an amateur painter1 of the style of an amateur poet8 ,style is always the product of specialist study1 the peculiar contribution of specialism to culture4 ,english education in its present phase suffers from a lack of definite aim1 and from an external machinery which kills its vitality4 ,hitherto in this address ,i have been considering the aims which should govern education4 ,in this respect ,england halts between two opinions4 ,it has not decided whether to produce amateurs or experts4 ,the profound change in the world which the nineteenth century has produced is that the growth of knowledge has given foresight4 ,the amateur is essentially a man with appreciation and with immense versatility in mastering a given routine4 ,but he lacks the foresight which comes from special knowledge4 ,the object of this address is to suggest how to produce the expert without loss of the essential virtues of the amateur4 ,the machinery of our secondary education is rigid where it should be yielding1 and lax where it should be rigid4 ,every school is bound on pain of extinction to train its boys for a small set of definite examinations4 ,no headmaster has a free hand to develop his general education or his specialist studies in accordance with the opportunities of his school1 which are created by its staff1 its environment1 its class of boys1 and its endowments4 ,i suggest that no system of external tests which aims primarily at examining individual scholars can result in anything but educational waste4 ,primarily it is the schools and not the scholars which should be inspected4 ,each school should grant its own leaving certificates1 based on its own curriculum4 ,the standards of these schools should be sampled and corrected4 ,but the first requisite for educational reform is the school as a unit1 with its approved curriculum based on its own needs1 and evolved by its own staff4 ,if we fail to secure that1 we simply fall from one formalism into another1 from one dung-hill of inert ideas into another4 ,in stating that the school is the true educational unit in any national system for the safe-guarding of efficiency1 ,i have conceived the alternative system as being the external examination of the individual scholar4 ,but every ,scylla is faced by its ,charybdis--or1 in more homely language1 there is a ditch on both sides of the road4 ,it will be equally fatal to education if we fall into the hands of a supervising department which is under the impression that it can divide all schools into two or three rigid categories1 each type being forced to adopt a rigid curriculum4 ,when ,i say that the school is the educational unit1 ,i mean exactly what ,i say1 no larger unit1 no smaller unit4 ,each school must have the claim to be considered in relation to its special circumstances4 ,the classifying of schools for some purposes is necessary4 ,but no absolutely rigid curriculum1 not modified by its own staff1 should be permissible4 ,exactly the same principles apply1 with the proper modifications1 to universities and to technical colleges4 ,when one considers in its length and in its breadth the importance of this question of the education of a nation's young1 the broken lives1 the defeated hopes1 the national failures1 which result from the frivolous inertia with which it is treated1 it is difficult to restrain within oneself a savage rage4 ,in the conditions of modern life the ride is absolute1 the race which does not value trained intelligence is doomed4 ,not all your heroism1 not all your social charm1 not all your wit1 not all your victories on land or at sea1 can move back the finger of fate4 ,to-day we maintain ourselves4 ,to-morrow science will have moved forward yet one more step1 and there will be no appeal from the judgment which will then be pronounced on the uneducated4 ,we can be content with no less than the old summary of educational ideal which has been current at any time from the dawn of our civilisation4 ,the essence of education is that it be religious4 ,pray1 what is religious education8 ,a religious education is an education which inculcates duty and reverence4 ,duty arises from our potential control over the course of events4 ,where attainable knowledge could have changed the issue1 ignorance has the guilt of vice4 ,and the foundation of reverence is this perception1 that the present holds within itself the complete sum of existence1 backwards and forwards1 that whole amplitude of time1 which is eternity4 ,,chapter ,,ii ,,technical ,,education ,,and ,,its ,,relation ,,to ,,science ,,and ,,literature 7,presidential ,address to the ,mathematical ,association1 ,january1 #aiag7 ,,the subject of this address is ,technical ,education4 ,i wish to examine its essential nature and also its relation to a liberal education4 ,such an inquiry may help us to realise the conditions for the successful working of a national system of technical training4 ,it is also a very burning question among mathematical teachers2 for mathematics is included in most technological courses4 ,now it is unpractical to plunge into such a discussion without framing in our own minds the best ideal towards which we desire to work1 however modestly we may frame our hopes as to the result which in the near future is likely to be achieved4 ,people are shy of ideals2 and accordingly we find a formulation of the ideal state of mankind placed by a modern dramatist#a in the mouth of a mad priest3 ,in my dreams it is a country where the ,state is the ,church and the ,church the people3 three in one and one in three4 ,it is a commonwealth in which work is play and play is life3 three in one and one in three4 ,it is a temple in which the priest is the worshipper and the worshipper the worshipped3 three in one and one in three4 ,it is a godhead in which all life is human and all humanity divine3 three in one and one in three4 ,it is1 in short1 the dream of a madman4 ,now the part of this speech to which ,i would direct attention is embodied in the phrase1 ,it is a commonwealth in which work is play and play is life4 ,this is the ideal of technical education4 ,it sounds very mystical when we confront it with the actual facts1 the toiling millions1 tired1 discontented1 mentally indifferent1 and then the employers---- ,i am not undertaking a social analysis1 but ,i shall carry you with me when ,i admit that the present facts of society are a long way off this ideal4 ,furthermore1 we are agreed that an employer who conducted his workshop on the principle that work should be play would be ruined in a week4 ,the curse that has been laid on humanity1 in fable and in fact1 is1 that by the sweat of its brow shall it live4 ,but reason and moral intuition have seen in this curse the foundation for advance4 ,the early ,benedictine monks rejoiced in their labours because they conceived themselves as thereby made fellow-workers with ,christ4 ,stripped of its theological trappings1 the essential idea remains1 that work should be transfused with intellectual and moral vision and thereby turned into a joy1 triumphing over its weariness and its pain4 ,each of us will re-state this abstract formulation in a more concrete shape in accordance with his private outlook4 ,state it how you like1 so long as you do not lose the main point in your details4 ,however you phrase it1 it remains the sole real hope of toiling humanity2 and it is in the hands of technical teachers1 and of those who control their spheres of activity1 so to mould the nation that daily it may pass to its labours in the spirit of the monks of old4 ,the immediate need of the nation is a large supply of skilled workmen1 of men with inventive genius1 and of employers alert in the development of new ideas4 ,there is one--and only one--way to obtain these admirable results4 ,it is by producing workmen1 men of science1 and employers who enjoy their work4 ,view the matter practically in the light of our knowledge of average human nature4 ,is it likely that a tired1 bored workman1 however skilful his hands1 will produce a large output of first-class work8 ,he will limit his production1 will scamp his work1 and be an adept at evading inspection2 he will be slow in adapting himself to new methods2 he will be a focus of discontent1 full of unpractical revolutionary ideas1 controlled by no sympathetic apprehension of the real working of trade conditions4 ,if1 in the troubled times which may be before us1 you wish appreciably to increase the chance of some savage upheaval1 introduce widespread technical education and ignore the ,benedictine ideal4 ,society will then get what it deserves4 ,again1 inventive genius requires pleasurable mental activity as a condition for its vigorous exercise4 ,necessity is the mother of invention is a silly proverb4 ,necessity is the mother of futile dodges is much nearer to the truth4 ,the basis of the growth of modern invention is science1 and science is almost wholly the outgrowth of pleasurable intellectual curiosity4 ,the third class are the employers1 who are to be enterprising4 ,now it is to be observed that it is the successful employers who are the important people to get at1 the men with business connections all over the world1 men who are already rich4 ,no doubt there will always be a continuous process of rise and fall of businesses4 ,but it is futile to expect flourishing trade1 if in the mass the successful houses of business are suffering from atrophy4 ,now if these men conceive their businesses as merely indifferent means for acquiring other disconnected opportunities of life1 they have no spur to alertness4 ,they are already doing very well1 the mere momentum of their present business engagements will carry them on for their time4 ,they are not at all likely to bother themselves with the doubtful chances of new methods4 ,their real soul is in the other side of their life4 ,desire for money will produce hard-fistedness and not enterprise4 ,there is much more hope for humanity from manufacturers who enjoy their work than from those who continue in irksome business with the object of founding hospitals4 ,finally1 there can be no prospect of industrial peace so long as masters and men in the mass conceive themselves as engaged in a soulless operation of extracting money from the public4 ,enlarged views of the work performed1 and of the communal service thereby rendered1 can be the only basis on which to found sympathetic co-operation4 ,the conclusion to be drawn from this discussion is1 that alike for masters and for men a technical or technological education1 which is to have any chance of satisfying the practical needs of the nation1 must be conceived in a liberal spirit as a real intellectual enlightenment in regard to principles applied and services rendered4 ,in such an education geometry and poetry are as essential as turning lathes4 ,the mythical figure of ,plato may stand for modern liberal education as does that of ,st4 ,benedict for technical education4 ,we need not entangle ourselves in the qualifications necessary for a balanced representation of the actual thoughts of the actual men4 ,they are used here as symbolic figures typical of antithetical notions4 ,we consider ,plato in the light of the type of culture he now inspires4 ,in its essence a liberal education is an education for thought and for sthetic appreciation4 ,it proceeds by imparting a knowledge of the masterpieces of thought1 of imaginative literature1 and of art4 ,the action which it contemplates is command4 ,it is an aristocratic education implying leisure4 ,this ,platonic ideal has rendered imperishable services to ,european civilisation4 ,it has encouraged art1 it has fostered that spirit of disinterested curiosity which is the origin of science1 it has maintained the dignity of mind in the face of material force1 a dignity which claims freedom of thought4 ,plato did not1 like ,st4 ,benedict1 bother himself to be a fellow-worker with his slaves2 but he must rank among the emancipators of mankind4 ,his type of culture is the peculiar inspiration of the liberal aristocrat1 the class from which ,europe derives what ordered liberty it now possesses4 ,for centuries1 from ,pope ,nicholas ,v to the schools of the ,jesuits1 and from the ,jesuits to the modern headmasters of ,english public schools1 this educational ideal has had the strenuous support of the clergy4 ,for certain people it is a very good education4 ,it suits their type of mind and the circumstances amid which their life is passed4 ,but more has been claimed for it than this4 ,all education has been judged adequate or defective according to its approximation to this sole type4 ,the essence of the type is a large discursive knowledge of the best literature4 ,the ideal product of the type is the man who is acquainted with the best that has been written4 ,he will have acquired the chief languages1 he will have considered the histories of the rise and fall of nations1 the poetic expression of human feeling1 and have read the great dramas and novels4 ,he will also be well grounded in the chief philosophies1 and have attentively read those philosophic authors who are distinguished for lucidity of style4 ,it is obvious that1 except at the close of a long life1 he will not have much time for anything else if any approximation is to be made to the fulfilment of this programme4 ,one is reminded of the calculation in a dialogue of ,lucian that1 before a man could be justified in practising any one of the current ethical systems1 he should have spent a hundred and fifty years in examining their credentials4 ,such ideals are not for human beings4 ,what is meant by a liberal culture is nothing so ambitious as a full acquaintance with the varied literary expression of civilised mankind from ,asia to ,europe1 and from ,europe to ,america4 ,a small selection only is required2 but then1 as we are told1 it is a selection of the very best4 ,i have my doubts of a selection which includes ,xenophon and omits ,confucius1 but then ,i have read neither in the original4 ,the ambitious programme of a liberal education really shrinks to a study of some fragments of literature included in a couple of important languages4 ,but the expression of the human spirit is not confined to literature4 ,there are the other arts1 and there are the sciences4 ,also education must pass beyond the passive reception of the ideas of others4 ,powers of initiative must be strengthened4 ,unfortunately initiative does not mean just one acquirement--there is initiative in thought1 initiative in action1 and the imaginative initiative of art2 and these three categories require many subdivisions4 ,the field of acquirement is large1 and the individual so fleeting and so fragmentary3 classical scholars1 scientists1 headmasters are alike ignoramuses4 ,there is a curious illusion that a more complete culture was possible when there was less to know4 ,surely the only gain was1 that it was more possible to remain unconscious of ignorance4 ,it cannot have been a gain to ,plato to have read neither ,shakespeare1 nor ,newton1 nor ,darwin4 ,the achievements of a liberal education have in recent times not been worsened4 ,the change is that its pretensions have been found out4 ,my point is1 that no course of study can claim any position of ideal completeness4 ,nor are the omitted factors of subordinate importance4 ,the insistence in the ,platonic culture on disinterested intellectual appreciation is a psychological error4 ,action and our implication in the transition of events amid the evitable bond of cause to effect are fundamental4 ,an education which strives to divorce intellectual or sthetic life from these fundamental facts carries with it the decadence of civilisation4 ,essentially culture should be for action1 and its effect should be to divest labour from the associations of aimless toil4 ,art exists that we may know the deliverances of our senses as good4 ,it heightens the sense-world4 ,disinterested scientific curiosity is a passion for an ordered intellectual vision of the connection of events4 ,but the goal of such curiosity is the marriage of action to thought4 ,this essential intervention of action even in abstract science is often overlooked4 ,no man of science wants merely to know4 ,he acquires knowledge to appease his passion for discovery4 ,he does not discover in order to know1 he knows in order to discover4 ,the pleasure which art and science can give to toil is the enjoyment which arises from successfully directed intention4 ,also it is the same pleasure which is yielded to the scientist and to the artist4 ,the antithesis between a technical and a liberal education is fallacious4 ,there can be no adequate technical education which is not liberal1 and no liberal education which is not technical3 that is1 no education which does not impart both technique and intellectual vision4 ,in simpler language1 education should turn out the pupil with something he knows well and something he can do well4 ,this intimate union of practice and theory aids both4 ,the intellect does not work best in a vacuum4 ,the stimulation of creative impulse requires1 especially in the case of a child1 the quick transition to practice4 ,geometry and mechanics1 followed by workshop practice1 gain that reality without which mathematics is verbiage4 ,there are three main methods which are required in a national system of education1 namely1 the literary curriculum1 the scientific curriculum1 the technical curriculum4 ,but each of these curricula should include the other two4 ,what ,i mean is1 that every form of education should give the pupil a technique1 a science1 an assortment of general ideas1 and sthetic appreciation1 and that each of these sides of his training should be illuminated by the others4 ,lack of time1 even for the most favoured pupil1 makes it impossible to develop fully each curriculum4 ,always there must be a dominant emphasis4 ,the most direct sthetic training naturally falls in the technical curriculum in those cases when the training is that requisite for some art or artistic craft4 ,but it is of high importance in both a literary and a scientific education4 ,the educational method of the literary curriculum is the study of language1 that is1 the study of our most habitual method of conveying to others our states of mind4 ,the technique which should be acquired is the technique of verbal expression1 the science is the study of the structure of language and the analysis of the relations of language to the states of mind conveyed4 ,furthermore1 the subtle relations of language to feeling1 and the high development of the sense organs to which written and spoken words appeal1 lead to keen sthetic appreciations being aroused by the successful employment of language4 ,finally1 the wisdom of the world is preserved in the masterpieces of linguistic composition4 ,this curriculum has the merit of homogeneity4 ,all its various parts are co-ordinated and play into each other's hands4 ,we can hardly be surprised that such a curriculum1 when once broadly established1 should have claimed the position of the sole perfect type of education4 ,its defect is unduly to emphasise the importance of language4 ,indeed the varied importance of verbal expression is so overwhelming that its sober estimation is difficult4 ,recent generations have been witnessing the retreat of literature1 and of literary forms of expression1 from their position of unique importance in intellectual life4 ,in order truly to become a servant and a minister of nature something more is required than literary aptitudes4 ,a scientific education is primarily a training in the art of observing natural phenomena1 and in the knowledge and deduction of laws concerning the sequence of such phenomena4 ,but here1 as in the case of a liberal education1 we are met by the limitations imposed by shortness of time4 ,there are many types of natural phenomena1 and to each type there corresponds a science with its peculiar modes of observation1 and its peculiar types of thought employed in the deduction of laws4 ,a study of science in general is impossible in education1 all that can be achieved is the study of two or three allied sciences4 ,hence the charge of narrow specialism urged against any education which is primarily scientific4 ,it is obvious that the charge is apt to be well-founded2 and it is worth considering how1 within the limits of a scientific education and to the advantage of such an education1 the danger can be avoided4 ,such a discussion requires the consideration of technical education4 ,a technical education is in the main a training in the art of utilising knowledge for the manufacture of material products4 ,such a training emphasises manual skill1 and the co-ordinated action of hand and eye1 and judgment in the control of the process of construction4 ,but judgment necessitates knowledge of those natural processes of which the manufacture is the utilisation4 ,thus somewhere in technical training an education in scientific knowledge is required4 ,if you minimise the scientific side1 you will confine it to the scientific experts2 if you maximise it1 you will impart it in some measure to the men1 and--what is of no less importance--to the directors and managers of the businesses4 ,technical education is not necessarily allied exclusively to science on its mental side4 ,it may be an education for an artist or for apprentices to an artistic craft4 ,in that case sthetic appreciation will have to be cultivated in connection with it4 ,an evil side of the ,platonic culture has been its total neglect of technical education as an ingredient in the complete development of ideal human beings4 ,this neglect has arisen from two disastrous antitheses1 namely1 that between mind and body1 and that between thought and action4 ,i will here interject1 solely to avoid criticism1 that ,i am well aware that the ,greeks highly valued physical beauty and physical activity4 ,they had1 however1 that perverted sense of values which is the nemesis of slave-owning4 ,i lay it down as an educational axiom that in teaching you will come to grief as soon as you forget that your pupils have bodies4 ,this is exactly the mistake of the post-renaissance ,platonic curriculum4 ,but nature can be kept at bay by no pitchfork2 so in ,english education1 being expelled from the classroom1 she returned with a cap and bells in the form of all-conquering athleticism4 ,the connections between intellectual activity and the body1 though diffused in every bodily feeling1 are focussed in the eyes1 the ears1 the voice1 and the hands4 ,there is a co-ordination of senses and thought1 and also a reciprocal influence between brain activity and material creative activity4 ,in this reaction the hands are peculiarly important4 ,it is a moot point whether the human hand created the human brain1 or the brain created the hand4 ,certainly the connection is intimate and reciprocal4 ,such deep-seated relations are not widely atrophied by a few hundred years of disuse in exceptional families4 ,the disuse of hand-craft is a contributory cause to the brain-lethargy of aristocracies1 which is only mitigated by sport where the concurrent brain-activity is reduced to a minimum and the hand-craft lacks subtlety4 ,the necessity for constant writing and vocal exposition is some slight stimulus to the thought-power of the professional classes4 ,great readers1 who exclude other activities1 are not distinguished by subtlety of brain4 ,they tend to be timid conventional thinkers4 ,no doubt this is partly due to their excessive knowledge outrunning their powers of thought2 but it is partly due to the lack of brain-stimulus from the productive activities of hand or voice4 ,in estimating the importance of technical education we must rise above the exclusive association of learning with book-learning4 ,first-hand knowledge is the ultimate basis of intellectual life4 ,to a large extent book-learning conveys second-hand information1 and as such can never rise to the importance of immediate practice4 ,our goal is to see the immediate event of our lives as instances of our general ideas4 ,what the learned world tends to offer is one second-hand scrap of information illustrating ideas derived from another second-hand scrap of information4 ,the second-handedness of the learned world is the secret of its mediocrity4 ,it is tame because it has never been scared by facts4 ,the main importance of ,francis ,bacon's influence does not lie in any peculiar theory of inductive reasoning which he happened to express1 but in the revolt against second-hand information of which he was a leader4 ,the peculiar merit of a scientific education should be1 that it bases thought upon first-hand observation2 and the corresponding merit of a technical education is1 that it follows our deep natural instinct to translate thought into manual skill1 and manual activity into thought4 ,we are a ,mathematical ,association1 and it is natural to ask3 ,where do we come in8 ,we come in just at this point4 ,the thought which science evokes is logical thought4 ,now logic is of two kinds3 the logic of discovery and the logic of the discovered4 ,the logic of discovery consists in the weighing of probabilities1 in discarding details deemed to be irrelevant1 in divining the general rules according to which events occur1 and in testing hypotheses by devising suitable experiments4 ,this is inductive logic4 ,the logic of the discovered is the deduction of the special events which1 under certain circumstances1 would happen in obedience to the assumed laws of nature4 ,thus when the laws are discovered or assumed1 their utilisation entirely depends on deductive logic4 ,without deductive logic science would be entirely useless4 ,it is merely a barren game to ascend from the particular to the general1 unless afterwards we can reverse the process and descend from the general to the particular1 ascending and descending like the angels on ,jacob's ladder4 ,when ,newton had divined the law of gravitation he at once proceeded to calculate the earth's attractions on an apple at its surface and on the moon4 ,we may note in passing that inductive logic would be impossible without deductive logic4 ,thus ,newton's calculations were an essential step in his inductive verification of the great law4 ,now mathematics is nothing else than the more complicated parts of the art of deductive reasoning1 especially where it concerns number1 quantity1 and space4 ,in the teaching of science1 the art of thought should be taught3 namely1 the art of forming clear conceptions applying to first-hand experience1 the art of divining the general truths which apply1 the art of testing divinations1 and the art of utilising general truths by reasoning to more particular cases of some peculiar importance4 ,furthermore1 a power of scientific exposition is necessary1 so that the relevant issues from a confused mass of ideas can be stated clearly1 with due emphasis on important points4 ,by the time a science1 or a small group of sciences1 has been taught thus amply1 with due regard to the general art of thought1 we have gone a long way towards correcting the specialism of science4 ,the worst of a scientific education based1 as necessarily must be the case1 on one or two particular branches of science1 is that the teachers under the influence of the examination system are apt merely to stuff their pupils with the narrow results of these special sciences4 ,it is essential that the generality of the method be continually brought to light and contrasted with the speciality of the particular application4 ,a man who only knows his own science1 as a routine peculiar to that science1 does not even know that4 ,he has no fertility of thought1 no power of quickly seizing the bearing of alien ideas4 ,he will discover nothing1 and be stupid in practical applications4 ,this exhibition of the general in the particular is extremely difficult to effect1 especially in the case of younger pupils4 ,the art of education is never easy4 ,to surmount its difficulties1 especially those of elementary education1 is a task worthy of the highest genius4 ,it is the training of human souls4 ,mathematics1 well taught1 should be the most powerful instrument in gradually implanting this generality of idea4 ,the essence of mathematics is perpetually to be discarding more special ideas in favour of more general ideas1 and special methods in favour of general methods4 ,we express the conditions of a special problem in the form of an equation1 but that equation will serve for a hundred other problems1 scattered through diverse sciences4 ,the general reasoning is always the powerful reasoning1 because deductive cogency is the property of abstract form4 ,here1 again1 we must be careful4 ,we shall ruin mathematical education if we use it merely to impress general truths4 ,the general ideas are the means of connecting particular results4 ,after all1 it is the concrete special cases which are important4 ,thus in the handling of mathematics in your results you cannot be too concrete1 and in your methods you cannot be too general4 ,the essential course of reasoning is to generalise what is particular1 and then to particularise what is general4 ,without generality there is no reasoning1 without concreteness there is no importance4 ,concreteness is the strength of technical education4 ,i would remind you that truths which lack the highest generality are not necessarily concrete facts4 ,for example1 x y y x is an algebraic truth more general than #b #b #d4 ,but two and two make four is itself a highly general proposition lacking any element of concreteness4 ,to obtain a concrete proposition immediate intuition of a truth concerning particular objects is requisite2 for example1 these two apples and those apples together make four apples is a concrete proposition1 if you have direct perception or immediate memory of the apples4 ,in order to obtain the full realisation of truths as applying1 and not as empty formul1 there is no alternative to technical education4 ,mere passive observation is not sufficient4 ,in creation only is there vivid insight into the properties of the object thereby produced4 ,if you want to understand anything1 make it yourself1 is a sound rule4 ,your faculties will be alive1 your thoughts gain vividness by an immediate translation into acts4 ,your ideas gain that reality which comes from seeing the limits of their application4 ,in elementary education this doctrine has long been put into practice4 ,young children are taught to familiarise themselves with shapes and colours by simple manual operations of cutting out and of sorting4 ,but good though this is1 it is not quite what ,i mean4 ,that is practical experience before you think1 experience antecedent to thought in order to create ideas1 a very excellent discipline4 ,but technical education should be much more than that3 it is creative experience while you think1 experience which realises your thought1 experience which teaches you to co-ordinate act and thought1 experience leading you to associate thought with foresight and foresight with achievement4 ,technical education gives theory1 and a shrewd insight as to where theory fails4 ,a technical education is not to be conceived as a maimed alternative to the perfect ,platonic culture3 namely1 as a defective training unfortunately made necessary by cramped conditions of life4 ,no human being can attain to anything but fragmentary knowledge and a fragmentary training of his capacities4 ,there are1 however1 three main roads along which we can proceed with good hope of advancing towards the best balance of intellect and character3 these are the way of literary culture1 the way of scientific culture1 the way of technical culture4 ,no one of these methods can be exclusively followed without grave loss of intellectual activity and of character4 ,but a mere mechanical mixture of the three curricula will produce bad results in the shape of scraps of information never interconnected or utilised4 ,we have already noted as one of the strong points of the traditional literary culture that all its parts are co-ordinated4 ,the problem of education is to retain the dominant emphasis1 whether literary1 scientific1 or technical1 and without loss of co-ordination to infuse into each way of education something of the other two4 ,to make definite the problem of technical education fix attention on two ages3 one thirteen1 when elementary education ends2 and the other seventeen1 when technical education ends so far as it is compressed within a school curriculum4 ,i am aware that for artisans in junior technical schools a three-years' course would be more usual4 ,on the other hand1 for naval officers1 and for directing classes generally1 a longer time can be afforded4 ,we want to consider the principles to govern a curriculum which shall land these children at the age of seventeen in the position of having technical skill useful to the community4 ,their technical manual training should start at thirteen1 bearing a modest proportion to the rest of their work1 and should increase in each year finally to attain to a substantial proportion4 ,above all things it should not be too specialised4 ,workshop finish and workshop dodges1 adapted to one particular job1 should be taught in the commercial workshop1 and should form no essential part of the school course4 ,a properly trained worker would pick them up in no time4 ,in all education the main cause of failure is staleness4 ,technical education is doomed if we conceive it as a system for catching children young and for giving them one highly specialised manual aptitude4 ,the nation has need of a fluidity of labour1 not merely from place to place1 but also within reasonable limits of allied aptitudes1 from one special type of work to another special type4 ,i know that here ,i am on delicate ground1 and ,i am not claiming that men while they are specialising on one sort of work should spasmodically be set to other kinds4 ,that is a question of trade organisation with which educationalists have no concern4 ,i am only asserting the principles that training should be broader than the ultimate specialisation1 and that the resulting power of adaptation to varying demands is advantageous to the workers1 to the employers1 and to the nation4 ,in considering the intellectual side of the curriculum we must be guided by the principle of the co-ordination of studies4 ,in general1 the intellectual studies most immediately related to manual training will be some branches of science4 ,more than one branch will1 in fact1 be concerned2 and even if that be not the case1 it is impossible to narrow down scientific study to a single thin line of thought4 ,it is possible1 however1 provided that we do not press the classification too far1 roughly to classify technical pursuits according to the dominant science involved4 ,we thus find a sixfold division1 namely1 7#a7 ,geometrical techniques1 7#b7 ,mechanical techniques1 7#c7 ,physical techniques1 7#d7 ,chemical techniques1 7#e7 ,biological techniques1 7#f7 ,techniques of commerce and of social service4 ,by this division1 it is meant that apart from auxiliary sciences some particular science requires emphasis in the training for most occupations4 ,we can1 for example1 reckon carpentry1 ironmongery1 and many artistic crafts among geometrical techniques4 ,similarly agriculture is a biological technique4 ,probably cookery1 if it includes food catering1 would fall midway between biological1 physical1 and chemical sciences1 though of this ,i am not sure4 ,the sciences associated with commerce and social service would be partly algebra1 including arithmetic and statistics1 and partly geography and history4 ,but this section is somewhat heterogeneous in its scientific affinities4 ,anyhow the exact way in which technical pursuits are classified in relation to science is a detail4 ,the essential point is1 that with some thought it is possible to find scientific courses which illuminate most occupations4 ,furthermore1 the problem is well understood1 and has been brilliantly solved in many of the schools of technology and junior technical schools throughout the country4 ,in passing from science to literature1 in our review of the intellectual elements of technical education1 we note that many studies hover between the two3 for example1 history and geography4 ,they are both of them very essential in education1 provided that they are the right history and the right geography4 ,also books giving descriptive accounts of general results1 and trains of thought in various sciences fall in the same category4 ,such books should be partly historical and partly expository of the main ideas which have finally arisen4 ,prof4 ,r4 ,a4 ,gregory's recent book1 ,discovery1 and the ,home ,university ,library series illustrate my meaning4 ,their value in education depends on their quality as mental stimulants4 ,they must not be inflated with gas on the wonders of science1 and must be informed with a broad outlook4 ,it is unfortunate that the literary element in education has rarely been considered apart from grammatical study4 ,the historical reason is1 that when the modern ,platonic curriculum was being formed ,latin and ,greek were the sole keys which rendered great literature accessible4 ,but there is no necessary connection between literature and grammar4 ,the great age of ,greek literature was already past before the arrival of the grammarians of ,alexandria4 ,of all types of men to-day existing1 classical scholars are the most remote from the ,greeks of the ,periclean times4 ,mere literary knowledge is of slight importance4 ,the only thing that matters is1 how it is known4 ,the facts related are nothing4 ,literature only exists to express and develop that imaginative world which is our life1 the kingdom which is within us4 ,it follows that the literary side of a technical education should consist in an effort to make the pupils enjoy literature4 ,it does not matter what they know1 but the enjoyment is vital4 ,the great ,english ,universities1 under whose direct authority school-children are examined in plays of ,shakespeare1 to the certain destruction of their enjoyment1 should be prosecuted for soul-murder4 ,now there are two kinds of intellectual enjoyment3 the enjoyment of creation1 and the enjoyment of relaxation4 ,they are not necessarily separated4 ,a change of occupation may give the full tide of happiness which comes from the concurrence of both forms of pleasure4 ,the appreciation of literature is really creation4 ,the written word1 its music1 and its associations1 are only the stimuli4 ,the vision which they evoke is our own doing4 ,no one1 no genius other than our own1 can make our own life live4 ,but except for those engaged in literary occupations1 literature is also a relaxation4 ,it gives exercise to that other side which any occupation must suppress during the working hours4 ,art also has the same function in life as has literature4 ,to obtain the pleasure of relaxation requires no help4 ,the pleasure is merely to cease doing4 ,some such pure relaxation is a necessary condition of health4 ,its dangers are notorious1 and to the greater part of the necessary relaxation nature has affixed1 not enjoyment1 but the oblivion of sleep4 ,creative enjoyment is the outcome of successful effort and requires help for its initiation4 ,such enjoyment is necessary for high-speed work and for original achievement4 ,to speed up production with unrefreshed workmen is a disastrous economic policy4 ,temporary success will be at the expense of the nation1 which1 for long years of their lives1 will have to support worn-out artisans--unemployables4 ,equally disastrous is the alternation of spasms of effort with periods of pure relaxation4 ,such periods are the seed-times of degeneration1 unless rigorously curtailed4 ,the normal recreation should be change of activity1 satisfying the cravings of instincts4 ,games afford such activity4 ,their disconnection emphasises the relaxation1 but their excess leaves us empty4 ,it is here that literature and art should play an essential part in a healthily organised nation4 ,their services to economic production would be only second to those of sleep or of food4 ,i am not now talking of the training of an artist1 but of the use of art as a condition of healthy life4 ,it is analogous to sunshine in the physical world4 ,when we have once rid our minds of the idea that knowledge is to be exacted1 there is no especial difficulty or expense involved in helping the growth of artistic enjoyment4 ,all school-children could be sent at regular intervals to neighbouring theatres where suitable plays could be subsidised4 ,similarly for concerts and cinema films4 ,pictures are more doubtful in their popular attraction2 but interesting representations of scenes or ideas which the children have read about would probably appeal4 ,the pupils themselves should be encouraged in artistic efforts4 ,above all the art of reading aloud should be cultivated4 ,the ,roger de ,coverley essays of ,addison are perfect examples of readable prose4 ,art and literature have not merely an indirect effect on the main energies of life4 ,directly1 they give vision4 ,the world spreads wide beyond the deliverances of material sense1 with subtleties of reaction and with pulses of emotion4 ,vision is the necessary antecedent to control and to direction4 ,in the contest of races which in its final issues will be decided in the workshops and not on the battle-field1 the victory will belong to those who are masters of stores of trained nervous energy1 working under conditions favourable to growth4 ,one such essential condition is ,art4 ,if there had been time1 there are other things which ,i should like to have said3 for example1 to advocate the inclusion of one foreign language in all education4 ,from direct observation ,i know this to be possible for artisan children4 ,but enough has been put before you1 to make plain the principles with which we should undertake national education4 ,in conclusion1 ,i recur to the thought of the ,benedictines1 who saved for mankind the vanishing civilisation of the ancient world by linking together knowledge1 labour1 and moral energy4 ,our danger is to conceive practical affairs as the kingdom of evil1 in which success is only possible by the extrusion of ideal aims4 ,i believe that such a conception is a fallacy directly negatived by practical experience4 ,in education this error takes the form of a mean view of technical training4 ,our forefathers in the dark ages saved themselves by embodying high ideals in great organisations4 ,it is our task1 without servile imitation1 boldly to exercise our creative energies1 remembering amid discouragements that the coldest hour immediately precedes the dawn4 ,,footnotes3 ,footnote #a3 ,cf4 ,,bernard ,,shaw3 ,john ,bull's ,other ,island4 ,,chapter ,,iii ,a ,,polytechnic ,,in ,,war-,,time ,address at the ,prize ,distribution1 ,borough ,polytechnic ,institute1 ,southwark1 #afth ,february1 #aiag ,i ,,will commence by drawing your attention to some of the satisfactory features of the ,principal's report on the work of the ,institute during the past year4 ,it has been a year of great difficulties4 ,some of our staff are serving with the colours1 and our classes have been depleted4 ,but in spite of everything1 we have done very well4 ,first1 the average result in the examinations has been good1 surprisingly good in view of the present circumstances4 ,the ,governors attach great importance to the maintenance of a high average result2 it is the best single test of efficiency4 ,again1 our individual successes have been notable4 ,we have gained--,i say we because we are all one in our pleasure at these successes--we have gained two #hj ,l4,c4,c4 scholarships1 nineteen exhibitions1 in addition to a first-place1 and medals1 prizes and certificates4 ,all this is very satisfactory4 ,it tells of efficient teaching1 and of hard work and regular attendance on the part of the students4 ,we know that we are keeping up the standard of efficiency which in the past has been a source of pride to every one connected with this ,institute4 ,now all this good work does not come about by itself without any one making an effort4 ,such a record requires our skilled staff of teachers and organisers4 ,they have worked very hard during the last session under great difficulties1 in order to create the successful result which we are here to celebrate4 ,i know something about teaching4 ,it is very exacting work1 and can be made successful only by continual devotion4 ,i am sure that ,i am voicing your feelings1 and ,i know that ,i am expressing those of the ,governors1 when ,i thank the ladies and gentlemen of the staff very heartily for their services during the last session4 ,prize-givings are always pleasant occasions4 ,we have come here to think about our successes1 and to congratulate our students4 ,there is no more satisfactory ,governors' ,meeting in the course of the year than when we meet on this occasion1 and face our friends and tell them how pleased we are at the successful result of their hard work4 ,this evening ,i am in a doubly happy position1 for my colleagues have asked me to be their spokesman in tendering our good wishes to the prize-winners4 ,you have worked hard and you have done well1 and ,i am sure that you all deserve your successes2 they are a pleasure not only to you1 but in your homes and to your companions and fellow-students4 ,successful work here will enable you to acquire skill in your trades1 and thereby the better to earn your living4 ,earning a living is on the average no bad test of service rendered to the community4 ,a man who has made himself skilful in his trade and has done well for himself in his walk of life1 has in general good reason to believe that he is a citizen who has benefited his country4 ,it is an evil day for a nation when it loses respect for success in industry4 ,but if you steer your lives by the compass which points steadily to the ,north ,pole of personal success1 you will have missed your greatest chances in life4 ,the genial climate is in the south4 ,what ,i mean is this3 you must make up your mind to find the best part of your happiness in kindly helpful relations with others4 ,it should be our ambition to leave our own small corner of the world a little tidier and a little happier than when we entered it4 ,i am well aware that this is an old story2 but old stories are sometimes true1 and this is the biggest truth in the whole world4 ,the warm kindly feelings are the happy feelings4 ,the fortunate people are those whose minds are filled with thoughts in which they forget themselves and remember others4 ,it is not true that nature is a mere scene of struggle in which every one competes with his neighbour4 ,those communities thrive best and last longest which are filled with a spirit of mutual help4 ,the future of the country lies with you4 ,the crown of your success is the promise of future work1 often unrecognised work1 done under discouragement1 but done steadily and cheerfully4 ,it is on you that the country depends for the maintenance and the growth of those ideals without which a race withers4 ,do not be discouraged by difficulties which seem unsurmountable4 ,the conditions of life which mould us all are modified by our will1 by our energy1 and by the purity of our intentions4 ,if we may judge of intensity of feeling by length of memory1 the enjoyment of receiving a prize bites very deep4 ,across the space of more than forty years1 before many of your parents were born1 or when they were being carried about in long clothes1 ,i can remember1 as if it were yesterday1 the occasion when ,i received my first prize at school4 ,i can see the medival school-room1 the headmaster1 and my companions4 ,perhaps some of you1 when a generation has passed by1 will remember the scene to-night--this ,stanley ,gymnasium recalling the memory of ,miss ,maude ,stanley1 who devoted to our welfare so much of her energy and her thought--the adjoining ,edric ,hall associated with the name of ,mr4 ,edric ,bayley1 the ,father of the ,institute2 ,mr4 ,millis and ,miss ,smith1 the first ,principal and the first ,lady ,superintendent1 the architects of our prosperity2 ,mr4 ,leonard ,spicer1 our ,chairman and member of a family and of a firm known throughout the world1 and respected in proportion as they are known4 ,and the cause why to-night we are a small gathering is one more reason why this assembly can never slip from your memory4 ,we meet at a moment when ,england stands in as deadly a peril as in any previous moment of her history--such peril as when the ,spanish ships of the ,armada rode in the ,english ,channel1 or when ,napoleon watched our coast across the ,strait of ,dover4 ,the present danger can be overcome only by the same courage as that which saved our freedom in those former times4 ,therefore1 to-night1 in recalling the activities of the various sections of our society which form this great ,polytechnic ,institute1 our thoughts go further afield4 ,they travel by land and by sea1 till they bring before our minds the gallant band whom this ,institute has sent to the ,front--more than #hjj of our members are with the ,colours4 ,what our fighting men have done for us1 for the world in general1 and for the future of ,england1 is so overwhelming that words cannot praise them enough4 ,i will just say one thing to you3 ,when you read of great deeds done in past times1 of perils encountered1 of adventures1 of undaunted courage1 of patriotism1 of self-sacrifice1 of suffering endured for noble cause1 you each can say--,i1 too1 have known such heroes2 they are among my countrymen1 they are among my fellow-workers1 they are among my fellow-students and companions1 they are among the dear inmates of my home4 ,and for those who have fallen1 it is for us to erect a monument sufficient to transmit to future ages the memory of their sacrifice4 ,for this purpose there is only one memorial which can suffice1 namely1 the cause for which they died4 ,the greatness of ,england1 the future of ,england1 has been left by them to our keeping4 ,guard it well4 ,the greatness of a country is nothing else than the greatness of the lives of the men and of the women who compose it4 ,do not look round and think who ought to be great ,englishmen--be great yourselves--you are the people to achieve it1 you who are sitting here to-night4 ,there can be no substitute service for this purpose4 ,it is the collective energy of the whole people that will be needed to fashion a new ,england worthy of the sufferings which for its sake have been endured4 ,a few days ago ,i asked a man who has worked in ,egypt for many years under ,lord ,kitchener1 what he would pick out as the best sign of ,lord ,kitchener's greatness4 ,he answered1 whatever ,kitchener set himself to do1 thereby became important4 ,now that is the secret of it all--take hold of your opportunities and make them important4 ,here we are in this ,borough ,polytechnic4 ,what an opportunity it represents4 ,this ,institute is a centre for social meeting1 a centre for recreation1 a centre for education1 a centre for discussion4 ,we will not sacrifice any one of our sides4 ,they must all be part of the greatness which we claim4 ,make them all first-rate4 ,consider first the social and recreative sides4 ,for heaven's sake don't think that you must be dull in order to be great4 ,there is no finer test of a nation than the way in which it fashions its amusements4 ,three centuries ago after the ,armada we made a good start in ,southwark4 ,shakespeare had his theatre here and wrote his plays to be acted in this borough4 ,he has walked these streets1 and if you had met him in ,westminster he would1 quite likely1 have told you that he was going down to the ,elephant4 ,and even now the performances given at the ,old ,vic are among the best in ,london for the purpose of seeing his plays properly acted4 ,what ,southwark has done for the drama1 she can do for the other arts1 by using this ,institute as the instrument for her energies4 ,why should we not be a centre for artistic enterprise--,i mean for our own art and our own enterprise1 thought of by ourselves and enjoyed by ourselves and carried through by ourselves8 ,we shall not always enjoy each others' creations1 but the great point is to make our own efforts4 ,of course all efforts require preparation and stimulus and knowledge of what others are doing4 ,at the present time--interrupted for the moment by the war--a great revolution in the art of painting is in progress throughout the world4 ,its centres are ,paris and ,italy and ,london and ,munich1 and its origin in the far east1 in ,china and ,japan4 ,there are two sides as in every revolution1 the ,conservatives and the ,revolutionists4 ,our own frescoes in a neighbouring room represent an early stage of the movement in ,london4 ,why should we not know all about it--obtain loans of pictures which illustrate its phases and its cross currents1 and compare these with examples of the old style8 ,but pictures are only one phase of art1 and not the sort of art which we ourselves can produce most easily4 ,there are music1 dancing1 recitation1 literature1 carving and modelling1 and the various decorative arts1 such as embroidery1 bookbinding1 dress-making and upholstery4 ,this list1 incomplete as it is1 tells us two great truths--you cannot separate art and recreation1 and you cannot separate art and business4 ,the list includes items which we consider as amusements1 and items which we think of as business4 ,we began with dancing and ended with upholstery4 ,make them all beautiful4 ,beautiful things have dignity4 ,enjoy the rhythm of your dancing and admire the beauty of your embroidery or your bookbinding4 ,in whatever you do1 have an ideal of excellence4 ,any separation between art and work is not only an error1 but it is very bad business4 ,our brave allies1 the ,french1 have made ,paris the art centre of the world4 ,they have built up and maintain their large and lucrative trade in the decorative products of ,france1 mainly by reason of three qualities which they possess4 ,in the first place1 they enjoy art themselves1 and reverence it4 ,in the second place1 they have a tremendous power of hard work4 ,and in the third place1 every ,frenchman1 and still more every ,frenchwoman1 have within them an immense fund of common sense4 ,the threefold secret is1 ,love of ,art1 ,industry1 and ,common ,sense4 ,to make available our industry and common sense in the trades where they are wanted1 rigorous training in schools of design and technique are necessary4 ,we have such departments here4 ,but all such training of you will be a failure unless you yourselves enjoy art and beauty as a natural recreation4 ,a technical school of training is like a deep1 narrow well1 sunk with careful labour to tap the underground river of water which flows below the surface of our natures4 ,but your well will be dry unless the bright warm sun has first drawn up the vapour from the wide ocean1 and the free untrammelled breezes have carried the clouds hither and thither1 until at length they break1 as it were by chance over the distant hills and soak the land with their downpour4 ,what ,i have said about art is a parable which applies to other occupations and other studies4 ,it is more than a parable2 it is the literal truth4 ,the love of art is the love of excellence1 it is the enjoyment of the triumph of design over the shapeless products of chance forces4 ,an engineer1 who is worth his salt1 loves the beauty of his machines1 shown in their adjustment of parts and in their swift1 smooth motions4 ,he loves also the sense of foresight and of insight which knowledge can give him4 ,people say that machinery and commerce are driving beauty out of the modern world4 ,i do not believe it4 ,a new beauty is being added1 a more intellectual beauty1 appealing to the understanding as much as to the eye4 ,the wonder of ,london ever takes the mind with fresh astonishment4 ,the city possesses parks1 and palaces1 and cathedrals4 ,but no other parts of it surpass in wonder its houses of business and its workshops and its factories4 ,in the next few years the future of the world will be decided for centuries to come4 ,the battles of this war are only the first part of the contest between races1 and between the ways of life for which those races stand4 ,we believe that ,england1 with its various peoples and communities scattered in islands and continents beyond the seas1 stands for ways of life infinitely precious1 the way of humanity1 the way of liberty1 the way of self-government1 the way of good order based on toleration and kindly feeling1 the way of peaceful industry4 ,the final decision in this struggle will be found in the workshops of the world4 ,it lies in your hands4 ,statesmen and emperors will only register the results which you have achieved4 ,your weapons will be skill1 and energy1 and knowledge4 ,you will require a sane understanding of your own rights1 and a sane understanding of the rights and the difficulties of other classes4 ,the greatness of ,england will be your greatness1 and its success your success4 ,the arsenal for war is at ,woolwich4 ,this ,polytechnic ,institute is an arsenal for peace1 where you can find the weapons for the conquest of your lives4 ,,chapter ,,iv ,,the ,,mathematical ,,curriculum 7,presidential ,address to the ,london ,branch of the ,mathematical ,association1 #aiab7 ,,the situation in regard to education at the present time cannot find its parallel without going back for some centuries to the break-up of the medival traditions of learning4 ,then1 as now1 the traditional intellectual outlook1 despite the authority which it had justly acquired from its notable triumphs1 had grown to be too narrow for the interests of mankind4 ,the result of this shifting of human interest was a demand for a parallel shifting of the basis of education1 so as to fit the pupils for the ideas which later in life would in fact occupy their minds4 ,any serious fundamental change in the intellectual outlook of human society must necessarily be followed by an educational revolution4 ,it may be delayed for a generation by vested interests or by the passionate attachment of some leaders of thought to the cycle of ideas within which they received their own mental stimulus at an impressionable age4 ,but the law is inexorable that education to be living and effective must be directed to informing pupils with those ideas1 and to creating for them those capacities which will enable them to appreciate the current thought of their epoch4 ,there is no such thing as a successful system of education in a vacuum1 that is to say1 a system which is divorced from immediate contact with the existing intellectual atmosphere4 ,education which is not modern shares the fate of all organic things which are kept too long4 ,but the blessed word modern does not really solve our difficulties4 ,what we mean is1 relevant to modern thought1 either in the ideas imparted or in the aptitudes produced4 ,something found out only yesterday may not really be modern in this sense4 ,it may belong to some bygone system of thought prevalent in a previous age1 or1 what is very much more likely1 it may be too recondite4 ,when we demand that education should be relevant to modern thought1 we are referring to thoughts broadly spread throughout cultivated society4 ,it is this question of the unfitness of recondite subjects for use in general education which ,i wish to make the keynote of my address this afternoon4 ,it is in fact rather a delicate subject for us mathematicians4 ,outsiders are apt to accuse our subject of being recondite4 ,let us grasp the nettle at once and frankly admit that in general opinion it is the very typical example of reconditeness4 ,by this word ,i do not mean difficulty1 but that the ideas involved are of highly special application1 and rarely influence thought4 ,this liability to reconditeness is the characteristic evil which is apt to destroy the utility of mathematics in liberal education4 ,so far as it clings to the educational use of the subject1 so far we must acquiesce in a miserably low level of mathematical attainment among cultivated people in general4 ,i yield to no one in my anxiety to increase the educational scope of mathematics4 ,the way to achieve this end is not by a mere blind demand for more mathematics4 ,we must face the real difficulty which obstructs its extended use4 ,is the subject recondite8 ,now1 viewed as a whole1 ,i think it is4 ,securus judicat orbis terrarum--the general judgment of mankind is sure4 ,the subject as it exists in the minds and in the books of students of mathematics is recondite4 ,it proceeds by deducing innumerable special results from general ideas1 each result more recondite than the preceding4 ,it is not my task this afternoon to defend mathematics as a subject for profound study4 ,it can very well take care of itself4 ,what ,i want to emphasise is1 that the very reasons which make this science a delight to its students are reasons which obstruct its use as an educational instrument--namely1 the boundless wealth of deductions from the interplay of general theorems1 their complication1 their apparent remoteness from the ideas from which the argument started1 the variety of methods1 and their purely abstract character which brings1 as its gift1 eternal truth4 ,of course1 all these characteristics are of priceless value to students2 for ages they have fascinated some of the keenest intellects4 ,my only remark is that1 except for a highly selected class1 they are fatal in education4 ,the pupils are bewildered by a multiplicity of detail1 without apparent relevance either to great ideas or to ordinary thoughts4 ,the extension of this sort of training in the direction of acquiring more detail is the last measure to be desired in the interests of education4 ,the conclusion at which we arrive is1 that mathematics1 if it is to be used in general education1 must be subjected to a rigorous process of selection and adaptation4 ,i do not mean1 what is of course obvious1 that however much time we devote to the subject the average pupil will not get very far4 ,but that1 however limited the progress1 certain characteristics of the subject1 natural at any stage1 must be rigorously excluded4 ,the science as presented to young pupils must lose its aspect of reconditeness4 ,it must1 on the face of it1 deal directly and simply with a few general ideas of far-reaching importance4 ,now1 in this matter of the reform of mathematical instruction1 the present generation of teachers may take a very legitimate pride in its achievements4 ,it has shown immense energy in reform1 and has accomplished more than would have been thought possible in so short a time4 ,it is not always recognised how difficult is the task of changing a well-established curriculum entrenched behind public examinations4 ,but for all that1 great progress has been made1 and1 to put the matter at its lowest1 the old dead tradition has been broken up4 ,i want to indicate this afternoon the guiding idea which should direct our efforts at reconstruction4 ,i have already summed it up in a phrase1 namely1 we must aim at the elimination of reconditeness from the educational use of the subject4 ,our courses of instruction should be planned to illustrate simply a succession of ideas of obvious importance4 ,all pretty divagations should be rigorously excluded4 ,the goal to be aimed at is that the pupil should acquire familiarity with abstract thought1 should realise how it applies to particular concrete circumstances1 and should know how to apply general methods to its logical investigation4 ,with this educational ideal nothing can be worse than the aimless accretion of theorems in our text-books1 which acquire their position merely because the children can be made to learn them and examiners can set neat questions on them4 ,the bookwork to be learnt should all be very important as illustrating ideas4 ,the examples set--and let there be as many examples as teachers find necessary--should be direct illustrations of the theorems1 either by way of abstract particular cases or by way of application to concrete phenomena4 ,here it is worth remarking that it is quite useless to simplify the bookwork1 if the examples set in examinations in fact require an extended knowledge of recondite details4 ,there is a mistaken idea that problems test ability and genius1 and that bookwork tests cram4 ,this is not my experience4 ,only boys who have been specially crammed for scholarships can ever do a problem paper successfully4 ,bookwork properly set1 not in mere snippets according to the usual bad plan1 is a far better test of ability1 provided that it is supplemented by direct examples4 ,but this is a digression on the bad influence of examinations on teaching4 ,the main ideas which lie at the base of mathematics are not at all recondite4 ,they are abstract4 ,but one of the main objects of the inclusion of mathematics in a liberal education is to train the pupils to handle abstract ideas4 ,the science constitutes the first large group of abstract ideas which naturally occur to the mind in any precise form4 ,for the purposes of education1 mathematics consists of the relations of number1 the relations of quantity1 and the relations of space4 ,this is not a general definition of mathematics1 which1 in my opinion1 is a much more general science4 ,but we are now discussing the use of mathematics in education4 ,these three groups of relations1 concerning number1 quantity1 and space1 are interconnected4 ,now1 in education we proceed from the particular to the general4 ,accordingly1 children should be taught the use of these ideas by practice among simple examples4 ,my point is this3 ,the goal should be1 not an aimless accumulation of special mathematical theorems1 but the final recognition that the preceding years of work have illustrated those relations of number1 and of quantity1 and of space1 which are of fundamental importance4 ,such a training should lie at the base of all philosophical thought4 ,in fact elementary mathematics rightly conceived would give just that philosophical discipline of which the ordinary mind is capable4 ,but what at all costs we ought to avoid1 is the pointless accumulation of details4 ,as many examples as you like2 let the children work at them for terms1 or for years4 ,but these examples should be direct illustrations of the main ideas4 ,in this way1 and this only1 can the fatal reconditeness be avoided4 ,i am not now speaking in particular of those who are to be professional mathematicians1 or of those who for professional reasons require a knowledge of certain mathematical details4 ,we are considering the liberal education of all students1 including these two classes4 ,this general use of mathematics should be the simple study of a few general truths1 well illustrated by practical examples4 ,this study should be conceived by itself1 and completely separated in idea from the professional study mentioned above1 for which it would make a most excellent preparation4 ,its final stage should be the recognition of the general truths which the work done has illustrated4 ,as far as ,i can make out1 at present the final stage is the proof of some property of circles connected with triangles4 ,such properties are immensely interesting to mathematicians4 ,but are they not rather recondite1 and what is the precise relation of such theorems to the ideal of a liberal education8 ,the end of all the grammatical studies of the student in classics is to read ,virgil and ,horace--the greatest thoughts of the greatest men4 ,are we content1 when pleading for the adequate representation in education of our own science1 to say that the end of a mathematical training is that the student should know the properties of the nine-point circle8 ,i ask you frankly1 is it not rather a come down8 ,this generation of mathematical teachers has done so much strenuous work in the way of reorganising mathematical instruction that there is no need to despair of its being able to elaborate a curriculum which shall leave in the minds of the pupils something even nobler than the ambiguous case4 ,let us think how this final review1 closing the elementary course1 might be conducted for the more intelligent pupils4 ,partly no doubt it requires a general oversight of the whole work done1 considered without undue detail so as to emphasise the general ideas used1 and their possibilities of importance when subjected to further study4 ,also the analytical and geometrical ideas find immediate application in the physical laboratory where a course of simple experimental mechanics should have been worked through4 ,here the point of view is twofold1 the physical ideas and the mathematical ideas illustrate each other4 ,the mathematical ideas are essential to the precise formulation of the mechanical laws4 ,the idea of a precise law of nature1 the extent to which such laws are in fact verified in our experience1 and the rle of abstract thought in their formulation1 then become practically apparent to the pupil4 ,the whole topic of course requires detailed development with full particular illustration1 and is not suggested as requiring merely a few bare abstract statements4 ,it would1 however1 be a grave error to put too much emphasis on the mere process of direct explanation of the previous work by way of final review4 ,my point is1 that the latter end of the course should be so selected that in fact the general ideas underlying all the previous mathematical work should be brought into prominence4 ,this may well be done by apparently entering on a new subject4 ,for example1 the ideas of quantity and the ideas of number are fundamental to all precise thought4 ,in the previous stages they will not have been sharply separated2 and children are1 rightly enough1 pushed on to algebra without too much bother and quantity4 ,but the more intelligent among them at the end of their curriculum would gain immensely by a careful consideration of those fundamental properties of quantity in general which lead to the introduction of numerical measurement4 ,this is a topic which also has the advantage that the necessary books are actually to hand4 ,euclid's fifth book is regarded by those qualified to judge as one of the triumphs of ,greek mathematics4 ,it deals with this very point4 ,nothing can be more characteristic of the hopelessly illiberal character of the traditional mathematical education than the fact that this book has always been omitted4 ,it deals with ideas1 and therefore was ostracised4 ,of course a careful selection of the more important propositions and a careful revision of the argument are required4 ,this also is to hand in the publications of my immediate predecessor in the office of president1 ,prof4 ,hill4 ,furthermore1 in ,sir ,t4 ,l4 ,heath's complete edition of ,euclid1 there is a full commentary embodying most of what has been said and thought on the point4 ,thus it is perfectly easy for teachers to inform themselves generally on the topic4 ,the whole book would not be wanted1 but just the few propositions which embody the fundamental ideas4 ,the subject is not fit for backward pupils2 but certainly it could be made interesting to the more advanced class4 ,there would be great scope for interesting discussion as to the nature of quantity1 and the tests which we should apply to ascertain when we are dealing with quantities4 ,the work would not be at all in the air1 but would be illustrated at every stage by reference to actual examples of cases where the quantitative character is absent1 or obscure1 or doubtful1 or evident4 ,temperature1 heat1 electricity1 pleasure and pain1 mass and distance could all be considered4 ,another idea which requires illustration is that of functionality4 ,a function in analysis is the counterpart of a law in the physical universe1 and of a curve in geometry4 ,children have studied the relations of functions to curves from the first beginning of their study of algebra1 namely in drawing graphs4 ,of recent years there has been a great reform in respect to graphs4 ,but at its present stage it has either gone too far or not far enough4 ,it is not enough merely to draw a graph4 ,the idea behind the graph--like the man behind the gun--is essential in order to make it effective4 ,at present there is some tendency merely to set the children to draw curves1 and there to leave the whole question4 ,in the study of simple algebraic functions and of trigonometrical functions we are initiating the study of the precise expression of physical laws4 ,curves are another way of representing these laws4 ,the simple fundamental laws--such as the inverse square and the direct distance--should be passed under review1 and the applications of the simple functions to express important concrete cases of physical laws considered4 ,i cannot help thinking that the final review of this topic might well take the form of a study of some of the main ideas of the differential calculus applied to simple curves4 ,there is nothing particularly difficult about the conception of a rate of change2 and the differentiation of a few powers of x1 such as x#b1 x#c1 etc41 could easily be effected2 perhaps by the aid of geometry even sin x and cos x could be differentiated4 ,if we once abandon our fatal habit of cramming the children with theorems which they do not understand1 and will never use1 there will be plenty of time to concentrate their attention on really important topics4 ,we can give them familiarity with conceptions which really influence thought4 ,before leaving this topic of physical laws and mathematical functions1 there are other points to be noticed4 ,the fact that the precise law is never really verified by observation in its full precision is capable of easy illustration and of affording excellent examples4 ,again1 statistical laws1 namely laws which are only satisfied on the average by large numbers1 can easily be studied and illustrated4 ,in fact a slight study of statistical methods and their application to social phenomena affords one of the simplest examples of the application of algebraic ideas4 ,another way in which the students' ideas can be generalised is by the use of the ,history of ,mathematics1 conceived not as a mere assemblage of the dates and names of men1 but as an exposition of the general current of thought which occasioned the subjects to be objects of interest at the time of their first elaboration4 ,the use of the ,history of ,mathematics is to be considered at a later stage of our proceedings this afternoon4 ,accordingly ,i merely draw attention to it now1 to point out that perhaps it is the very subject which may best obtain the results for which ,i am pleading4 ,we have indicated two main topics1 namely general ideas of quantity and of laws of nature1 which should be an object of study in the mathematical curriculum of a liberal education4 ,but there is another side to mathematics which must not be overlooked4 ,it is the chief instrument for discipline in logical method4 ,now1 what is logical method1 and how can any one be trained in it8 ,logical method is more than the mere knowledge of valid types of reasoning and practice in the concentration of mind necessary to follow them4 ,if it were only this1 it would still be very important2 for the human mind was not evolved in the bygone ages for the sake of reasoning1 but merely to enable mankind with more art to hunt between meals for fresh food supplies4 ,accordingly few people can follow close reasoning without considerable practice4 ,more than this is wanted to make a good reasoner1 or even to enlighten ordinary people with knowledge of what constitutes the essence of the art4 ,the art of reasoning consists in getting hold of the subject at the right end1 of seizing on the few general ideas which illuminate the whole1 and of persistently marshalling all subsidiary facts round them4 ,nobody can be a good reasoner unless by constant practice he has realised the importance of getting hold of the big ideas and of hanging on to them like grim death4 ,for this sort of training geometry is1 ,i think1 better than algebra4 ,the field of thought of algebra is rather obscure1 whereas space is an obvious insistent thing evident to all4 ,then the process of simplification1 or abstraction1 by which all irrelevant properties of matter1 such as colour1 taste1 and weight1 are put aside is an education in itself4 ,again1 the definitions and the propositions assumed without proof illustrate the necessity of forming clear notions of the fundamental facts of the subject-matter and of the relations between them4 ,all this belongs to the mere prolegomena of the subject4 ,when we come to its development1 its excellence increases4 ,the learner is not initially confronted with any symbolism which bothers the memory by its rules1 however simple they may be4 ,also1 from the very beginning the reasoning1 if properly conducted1 is dominated by well-marked ideas which guide each stage of development4 ,accordingly the essence of logical method receives immediate exemplification4 ,let us now put aside for the moment the limitations introduced by the dullness of average pupils and the pressure on time due to other subjects1 and consider what geometry has to offer in the way of a liberal education4 ,i will indicate some stages in the subject1 without meaning that necessarily they are to be studied in this exclusive order4 ,the first stage is the study of congruence4 ,our perception of congruence is in practice dependent on our judgments of the invariability of the intrinsic properties of bodies when their external circumstances are varying4 ,but however it arises1 congruence is in essence the correlation of two regions of space1 point by point1 so that all homologous distances and all homologous angles are equal4 ,it is to be noticed that the definition of the equality of lengths and angles is their congruence1 and all tests of equality1 such as the use of the yard measure1 are merely devices for making immediate judgments of congruence easy4 ,i make these remarks to suggest that apart from the reasoning connected with it1 congruence1 both as an example of a larger and very far-reaching idea and also for its own sake1 is well worthy of attentive consideration4 ,the propositions concerning it elucidate the elementary properties of the triangle1 the parallelogram1 and the circle1 and of the relations of two planes to each other4 ,it is very desirable to restrict the proved propositions of this part within the narrowest bounds1 partly by assuming redundant axiomatic propositions1 and partly by introducing only those propositions of absolutely fundamental importance4 ,the second stage is the study of similarity4 ,this can be reduced to three or four fundamental propositions4 ,similarity is an enlargement of the idea of congruence1 and1 like that idea1 is another example of a one-to-one correlation of points of spaces4 ,any extension of study of this subject might well be in the direction of the investigation of one or two simple properties of similar and similarly situated rectilinear figures4 ,the whole subject receives its immediate applications in plans and maps4 ,it is important1 however1 to remember that trigonometry is really the method by which the main theorems are made available for use4 ,the third stage is the study of the elements of trigonometry4 ,this is the study of the periodicity introduced by rotation and of properties preserved in a correlation of similar figures4 ,here for the first time we introduce a slight use of the algebraic analysis founded on the study of number and quantity4 ,the importance of the periodic character of the functions requires full illustration4 ,the simplest properties of the functions are the only ones required for the solution of triangles1 and the consequent applications to surveying4 ,the wealth of formul1 often important in themselves1 but entirely useless for this type of study1 which crowd our books should be rigorously excluded1 except so far as they are capable of being proved by the pupils as direct examples of the bookwork4 ,this question of the exclusion of formul is best illustrated by considering this example of ,trigonometry1 though of course ,i may well have hit on an unfortunate case in which my judgment is at fault4 ,a great part of the educational advantage of the subject can be obtained by confining study to ,trigonometry of one angle and by exclusion of the addition formul for the sine and cosine of the sum of two angles4 ,the functions can be graphed1 and the solution of triangles effected4 ,thus the aspects of the science as 7#a7 embodying analytically the immediate results of some of the theorems deduced from congruence and similarity1 7#b7 as a solution of the main problem of surveying1 7#c7 as a study of the fundamental functions required to express periodicity and wave motion1 will all be impressed on the pupils' minds both by bookwork and example4 ,if it be desired to extend this course1 the addition formul should be added4 ,but great care should be taken to exclude specialising the pupils in the wealth of formul which comes in their train4 ,by exclude is meant that the pupils should not have spent time or energy in acquiring any facility in their deduction4 ,the teacher may find it interesting to work a few such examples before a class4 ,but such results are not among those which learners need retain4 ,also1 ,i would exclude the whole subject of circumscribed and inscribed circles both from ,trigonometry and from the previous geometrical courses4 ,it is all very pretty1 but ,i do not understand what its function is in an elementary non-professional curriculum4 ,accordingly1 the actual bookwork of the subject is reduced to very manageable proportions4 ,i was told the other day of an ,american college where the students are expected to know by heart ninety formul or results in ,trigonometry alone4 ,we are not quite so bad as that4 ,in fact1 in ,trigonometry we have nearly approached the ideal here sketched out as far as our elementary courses are concerned4 ,the fourth stage introduces ,analytical ,geometry4 ,the study of graphs in algebra has already employed the fundamental notions1 and all that is now required is a rigorously pruned course on the straight line1 the circle1 and the three types of conic sections1 defined by the forms of their equations4 ,at this point there are two remarks to be made4 ,it is often desirable to give our pupils mathematical information which we do not prove4 ,for example1 in co-ordinate geometry1 the reduction of the general equation of the second degree is probably beyond the capacities of most of the type of students whom we are considering4 ,but that need not prevent us from explaining the fundamental position of conics1 as exhausting the possible types of such curves4 ,the second remark is to advocate the entire sweeping away of geometrical conics as a separate subject4 ,naturally1 on suitable occasions the analysis of analytical geometry will be lightened by the use of direct deduction from some simple figure4 ,but geometrical conics1 as developed from the definition of a conic section by the focus and directrix property1 suffers from glaring defects4 ,it is hopelessly recondite4 ,the fundamental definition of a conic1 ,,sp e ,,pm1 usual in this subject at this stage1 is thoroughly bad4 ,it is very recondite1 and has no obvious importance4 ,why should such curves be studied at all1 any more than those defined by an indefinite number of other formul8 ,but when we have commenced the study of the ,cartesian methods1 the equations of the first and second degrees are naturally the first things to think about4 ,in this ideal course of ,geometry1 the fifth stage is occupied with the elements of ,projective ,geometry4 ,the general ideas of cross ratio and of projection are here fundamental4 ,projection is yet a more general instance of that one-to-one correlation which we have already considered under congruence and similarity4 ,here again we must avoid the danger of being led into a bewildering wealth of detail4 ,the intellectual idea which projective geometry is to illustrate is the importance in reasoning of the correlation of all cases which can be proved to possess in common certain identical properties4 ,the preservation of the projective properties in projection is the one important educational idea of the subject4 ,cross ratio only enters as the fundamental metrical property which is preserved4 ,the few propositions considered are selected to illustrate the two allied processes which are made possible by this procedure4 ,one is proof by simplification4 ,here the simplification is psychological and not logical--for the general case is logically the simplest4 ,what is meant is3 ,proof by considering the case which is in fact the most familiar to us1 or the easiest to think about4 ,the other procedure is the deduction of particular cases from known general truths1 as soon as we have a means of discovering such cases or a criterion for testing them4 ,the projective definition of conic sections and the identity of the results obtained with the curves derived from the general equation of the second degree are capable of simple exposition1 but lie on the border-line of the subject4 ,it is the sort of topic on which information can be given1 and the proofs suppressed4 ,the course of geometry as here conceived in its complete ideal--and ideals can never be realised--is not a long one4 ,the actual amount of mathematical deduction at each stage in the form of bookwork is very slight4 ,but much more explanation would be given1 the importance of each proposition being illustrated by examples1 either worked out or for students to work1 so selected as to indicate the fields of thought to which it applies4 ,by such a course the student would gain an analysis of the leading properties of space1 and of the chief methods by which they are investigated4 ,the study of the elements of mathematics1 conceived in this spirit1 would constitute a training in logical method together with an acquisition of the precise ideas which lie at the base of the scientific and philosophical investigations of the universe4 ,would it be easy to continue the excellent reforms in mathematical instruction which this generation has already achieved1 so as to include in the curriculum this wider and more philosophic spirit8 ,frankly1 ,i think that this result would be very hard to achieve as the result of single individual efforts4 ,for reasons which ,i have already briefly indicated1 all reforms in education are very difficult to effect4 ,but the continued pressure of combined effort1 provided that the ideal is really present in the minds of the mass of teachers1 can do much1 and effects in the end surprising modification4 ,gradually the requisite books get written1 still more gradually the examinations are reformed so as to give weight to the less technical aspects of the subject1 and then all recent experience has shown that the majority of teachers are only too ready to welcome any practicable means of rescuing the subject from the reproach of being a mechanical discipline4 ,,chapter ,v ,,the ,,principles ,,of ,,mathematics ,,in ,,relation ,,to ,,elementary ,,teaching 7,international ,congress of ,mathematicians1 ,cambridge1 ,august1 #aiab7 ,,we are concerned not with the advanced teaching of a few specialist mathematical students1 but with the mathematical education of the majority of boys in our secondary schools4 ,again these boys must be divided into two sections3 one section consists of those who desire to restrict their mathematical education2 the other section is made up of those who will require some mathematical training for their subsequent professional careers1 either in the form of definite mathematical results or in the form of mathematically trained minds4 ,i shall call the latter of these two sections the mathematical section1 and the former the non-mathematical section4 ,but ,i must repeat that by the mathematical section is meant that large number of boys who desire to learn more than the minimum amount of mathematics4 ,furthermore1 most of my remarks about these sections of boys apply also to elementary classes of our ,university students4 ,the subject of this paper is the investigation of the place which should be occupied by modern investigations respecting mathematical principles in the education of both of these sections of school-boys4 ,to find a foothold from which to start the inquiry1 let us ask why the non-mathematical section should be taught any mathematics at all beyond the barest elements of arithmetic4 ,what are the qualities of mind which a mathematical training is designed to produce when it is employed as an element in a liberal education8 ,my answer1 which applies equally to both sections of students1 is that there are two allied forms of mental discipline which should be acquired by a well-designed mathematical course4 ,these two forms though closely allied are perfectly distinct4 ,the first form of discipline is not in its essence logical at all4 ,it is the power of clearly grasping abstract ideas1 and of relating them to particular circumstances4 ,in other words1 the first use of mathematics is to strengthen the power of abstract thought4 ,i repeat that in its essence this has nothing to do with logic1 though as a matter of fact a logical discipline is the best method of producing the desired effect4 ,it is not the philosophical theory of abstract ideas which is to be acquired1 but the habit and the power of using them4 ,there is one and only way of acquiring the habit and the power of using anything1 that is by the simple common-place method of habitually using it4 ,there is no other short cut4 ,if in education we desire to produce a certain conformation of mind1 we must day by day1 and year by year1 accustom the students' minds to grow into the desired structural shape4 ,thus to teach the power of grasping abstract ideas and the habit of using them1 we must select a group of such ideas1 which are important and are also easy to think about because they are clear and definite4 ,the fundamental mathematical truths concerning geometry1 ratio1 quantity1 and number1 satisfy these conditions as do no others4 ,hence1 the fundamental universal position held by mathematics as an element of a liberal education4 ,but what are the fundamental mathematical truths concerning geometry1 quantity and number8 ,at this point we come to the great question of the relation between the modern science of the principles of mathematics and a mathematical education4 ,my answer to the question as to these fundamental mathematical truths is1 that in any absolute sense there are none4 ,there is no unique small body of independent primitive unproved propositions which are the necessary starting points of all mathematical reasoning on these subjects4 ,in mathematical reasoning the only absolute necessary pre-suppositions are those which make logical deduction possible4 ,between these absolute logical truths and so-called fundamental truths concerning geometry1 quantity and number1 there is a whole new world of mathematical subjects concerning the logic of propositions1 of classes1 and of relations4 ,but this subject is too abstract to form an elementary training ground in the difficult art of abstract thought4 ,it is for this reason that we have to make a compromise and start from such obvious general ideas as naturally occur to all men when they perceive objects with their senses4 ,in geometry1 the ideas elaborated by the ,greeks and presented by ,euclid are1 roughly speaking1 those adapted for our purpose1 namely1 ideas of volumes1 surfaces1 lines1 of straightness and of curvature1 of intersection and of congruence1 of greater and less1 of similarity1 shape1 and scale4 ,in fact1 we use in education those general ideas of spatial properties which must be habitually present in the mind of any one who is to observe the world of phenomena with understanding4 ,thus we come back to ,plato's opinion that for a liberal education1 geometry1 as he knew it1 is the queen of sciences4 ,in addition to geometry1 there remain the ideas of quantity1 ratio1 and of number4 ,this in practice means1 elementary algebra4 ,here the prominent ideas are those of any number1 in other words1 the use of the familiar x1 y1 z1 and of the dependence of variables on each other1 or otherwise1 the idea of functionality4 ,all this is to be gradually acquired by the continual use of the very simplest functions which we can devise3 of linear functions1 graphically represented by straight lines2 of quadratic functions1 graphically represented by parabolas2 and of those simple implicit functions1 graphically represented by conic sections4 ,thence1 with good fortune and a willing class1 we can advance to the ideas of rates of increase1 still confining ourselves to the simplest possible cases4 ,i wish here emphatically to remind you that both in geometry and in algebra a clear grasp of these general ideas is not what the pupil starts from1 it is the goal at which he is to arrive4 ,the method of progression is continual practice in the consideration of the simplest particular cases1 and the goal is not philosophical analysis but the power of use4 ,but how is he to practise himself in their use8 ,he cannot simply sit down and think of the relation y x #a1 he must employ it in some simple obvious way4 ,this brings us to the second power of mind which is to be produced by a mathematical training1 namely1 the power of logical reasoning4 ,here again1 it is not the knowledge of the philosophy of logic which it is essential to teach1 but the habit of thinking logically4 ,by logic1 ,i mean deductive logic4 ,deductive logic is the science of certain relations1 such as implication1 etc41 between general ideas4 ,when logic begins1 definite particular individual things have been banished4 ,i cannot relate logically this thing to that thing1 for example this pen to that pen1 except by the indirect way of relating some general idea which applies to this pen to some general idea which applies to that pen4 ,and the individualities of the two pens are quite irrelevant to the logical process4 ,this process is entirely concerned with the two general ideas4 ,thus the practice of logic is a certain way of employing the mind in the consideration of such ideas2 and an elementary mathematical training is in fact nothing else but the logical use of the general ideas respecting geometry and algebra which we have enumerated above4 ,it has therefore1 as ,i started this paper by stating1 a double advantage4 ,it makes the mind capable of abstract thought1 and it achieves this object by training the mind in the most important kind of abstract thought1 namely1 deductive logic4 ,i may remind you that other choices of a type of abstract thought might be made4 ,we might train the children to contemplate directly the beauty of abstract moral ideas1 in the hope of making them religious mystics4 ,the general practice of education has decided in favour of logic1 as exemplified in elementary mathematics4 ,we have now to answer the further question1 what is the rle of logical precision in the teaching of mathematics8 ,our general answer to the implied question is obvious3 logical precision is one of the two objects of the teaching of mathematics1 and it is the only weapon by which the teaching of mathematics can achieve its other object4 ,to teach mathematics is to teach logical precision4 ,a mathematical teacher who has not taught that has taught nothing4 ,but having stated this thesis in this unqualified way1 its meaning must be carefully explained2 for otherwise its real bearing on the problem will be entirely misunderstood4 ,logical precision is the faculty to be acquired4 ,it is the quality of mind which it is the object of the teaching to impart4 ,thus the habit of reading great literature is the goal at which a literary education aims4 ,but we do not expect a child to start its first lesson by reading for itself ,shakespeare4 ,we recognise that reading is impossible till the pupil has learnt its alphabet and can spell1 and then we start it with books of one syllable4 ,in the same way1 a mathematical education should grow in logical precision4 ,it is folly to expect the same careful logical analysis at the commencement of the training as would be appropriate at the end4 ,it is an entire misconception of my thesis to construe it as meaning that a mathematical training should assume in the pupil a power of concentrated logical thought4 ,my thesis is in fact the exact opposite1 namely1 that this power cannot be assumed1 and has got to be acquired1 and that a mathematical training is nothing else than the process of acquiring it4 ,my whole groundwork of assumption is that this power does not initially exist in a fully developed state4 ,of course like every other power which is acquired1 it must be developed gradually4 ,the various stages of development must be guided by the judgment and the genius of the teacher4 ,but what is essential is1 that the teacher should keep clearly in his mind that it is just this power of logical precise reasoning which is the whole object of his efforts4 ,if his pupils have in any measure gained this1 they have gained all4 ,we have not yet1 however1 fully considered this part of our subject4 ,logical precision is the full realisation of the steps of the argument4 ,but what are the steps of the argument8 ,the full statement of all the steps is far too elaborate and difficult an operation to be introduced into the mathematical reasoning of an educational curriculum4 ,such a statement involves the introduction of abstract logical ideas which are very difficult to grasp1 because there is so rarely any need to make them explicit in ordinary thought4 ,they are therefore not a fit subject-ground for an elementary education4 ,i do not think that it is possible to draw any theoretical line between those logical steps which form a theoretically full logical investigation1 and those which are full enough for most practical purposes1 including that of education4 ,the question is one of psychology1 to be solved by a process of experiment4 ,the object to be attained is to gain that amount of logical alertness which will enable its possessors to detect fallacy and to know the types of sound logical deduction4 ,the objects of going further are partly philosophical1 and also partly to lay bare abstract ideas whose investigation is in itself important4 ,but both these objects are foreign to education4 ,my opinion is1 that1 on the whole1 the type of logical precision handed down to us by the ,greek mathematicians is1 roughly speaking1 what we want4 ,in geometry1 this means the sort of precision which we find in ,euclid4 ,i do not mean that we should use his famous ,elements as a text-book1 nor that here and there a certain compression in his mode of exposition is not advisable4 ,all this is mere detail4 ,what ,i do mean is1 that the sort of logical transition which he made explicit1 we should make explicit1 and that the sort of transition which he omits1 we should omit4 ,i doubt1 however1 whether it is desirable to plunge the student into the full rigour of euclidean geometry without some mitigation4 ,it is for this reason that the modern habit1 at least in ,england1 of laying great stress in the initial stages on training the pupil in simple constructions from numerical data is to be praised4 ,it means that after a slight amount of reasoning on the euclidean basis of accuracy1 the mind of the learner is relieved by doing the things in various special cases1 and noting by rough measurements that the desired results are actually attained4 ,it is important1 however1 that the measurements be not mistaken for the proofs4 ,their object is to make the beginner apprehend what the abstract ideas really mean4 ,again in algebra1 the notation and the practical use of the symbols should be acquired in the simplest cases1 and the more theoretical treatment of the symbolism reserved to a suitable later stage4 ,my rule would be initially to learn the meaning of the ideas by a crude practice in simple ways1 and to refine the logical procedure in preparation for an advance to greater generality4 ,in fact the thesis of my paper can be put in another way thus1 the object of a mathematical education is1 to acquire the powers of analysis1 of generalisation1 and of reasoning4 ,the two processes of analysis and generalisation were in my previous statement put together as the power of grasping abstract ideas4 ,but in order to analyse and to generalise1 we must commence with the crude material of ideas which are to be analysed and generalised4 ,accordingly it is a positive error in education to start with the ultimate products of this process1 namely the ideas in their refined analysed and generalised forms4 ,we are thereby skipping an important part of the training1 which is to take the ideas as they actually exist in the child's mind1 and to exercise the child in the difficult art of civilising them and clothing them4 ,the schoolmaster is in fact a missionary1 the savages are the ideas in the child's mind2 and the missionary shirks his main task if he refuse to risk his body among the cannibals4 ,at this point ,i should like to turn your attention to those pupils forming the mathematical section4 ,there is an idea1 widely prevalent1 that it is possible to teach mathematics of a relatively advanced type--such as differential calculus1 for instance--in a way useful to physicists and engineers without any attention to its logic or its theory4 ,this seems to me to be a profound mistake4 ,it implies that a merely mechanical knowledge without understanding of ways of arriving at mathematical results is useful in applied science4 ,it is of no use whatever4 ,the results themselves can all be found stated in the appropriate pocket books and in other elementary works of reference4 ,no one when applying a result need bother himself as to why it is true4 ,he accepts it and applies it4 ,what is of supreme importance in physics and in engineering is a mathematically trained mind1 and such a mind can only be acquired by a proper mathematical discipline4 ,i fully admit that the proper way to start such a subject as the differential calculus is to plunge quickly into the use of the notation in a few absurdly simple cases1 with a crude explanation of the idea of rates of increase4 ,the notation as thus known can then be used by the lecturers in the ,physical and ,engineering ,laboratories4 ,but the mathematical training of the applied scientists consists in making these ideas precise and the proofs accurate4 ,i hope that the thesis of this paper respecting the position of logical precision in the teaching of mathematics has been rendered plain4 ,the habit of logical precision with its necessary concentration of thought upon abstract ideas is not wholly possible in the initial stages of learning4 ,it is the ideal at which the teacher should aim4 ,also logical precision1 in the sense of logical explicitness1 is not an absolute thing3 it is an affair of more or less4 ,accordingly the quantity of explicitness to be introduced at each stage of progress must depend upon the practical judgment of the teacher4 ,lastly1 in a sense1 the instructed mind is less explicit2 for it travels more quickly over a well-remembered path1 and may save the trouble of putting into words trains of thought which are very obvious to it4 ,but on the other hand it atones for this rapidity by a concentration on every subtle point where a fallacy can lurk4 ,the habit of logical precision is the instinct for the subtle difficulty4 ,,chapter ,,vi ,,the ,,organisation ,,of ,,thought 7,presidential ,address to ,section ,a1 ,british ,association1 ,newcastle1 #aiaf7 ,,the subject of this address is the organisation of thought1 a topic evidently capable of many diverse modes of treatment4 ,i intend more particularly to give some account of that department of logical science with which some of my own studies have been connected4 ,but ,i am anxious1 if ,i can succeed in so doing1 to handle this account so as to exhibit the relation with certain considerations which underlie general scientific activities4 ,it is no accident that an age of science has developed into an age of organisation4 ,organised thought is the basis of organised action4 ,organisation is the adjustment of diverse elements so that their mutual relations may exhibit some predetermined quality4 ,an epic poem is a triumph of organisation1 that is to say1 it is a triumph in the unlikely event of its being a good epic poem4 ,it is the successful organisation of multitudinous sounds of words1 associations of words1 pictorial memories of diverse events and feelings ordinarily occurring in life1 combined with a special narrative of great events3 the whole so disposed as to excite emotions which1 as defined by ,milton1 are simple1 sensuous1 and passionate4 ,the number of successful epic poems is commensurate1 or rather1 is inversely commensurate1 with the obvious difficulty of the task of organisation4 ,science is the organisation of thought4 ,but the example of the epic poem warns us that science is not any organisation of thought4 ,it is an organisation of a certain definite type which we will endeavour to determine4 ,science is a river with two sources1 the practical source and the theoretical source4 ,the practical source is the desire to direct our actions to achieve predetermined ends4 ,for example1 the ,british nation1 fighting for justice1 turns to science1 which teaches it the importance of compounds of nitrogen4 ,the theoretical source is the desire to understand4 ,now ,i am going to emphasise the importance of theory in science4 ,but to avoid misconception ,i most emphatically state that ,i do not consider one source as in any sense nobler than the other1 or intrinsically more interesting4 ,i cannot see why it is nobler to strive to understand than to busy oneself with the right ordering of one's actions4 ,both have their bad sides2 there are evil ends directing actions1 and there are ignoble curiosities of the understanding4 ,the importance1 even in practice1 of the theoretical side of science arises from the fact that action must be immediate1 and takes place under circumstances which are excessively complicated4 ,if we wait for the necessities of action before we commence to arrange our ideas1 in peace we shall have lost our trade1 and in war we shall have lost the battle4 ,success in practice depends on theorists who1 led by other motives of exploration1 have been there before1 and by some good chance have hit upon the relevant ideas4 ,by a theorist ,i do not mean a man who is up in the clouds1 but a man whose motive for thought is the desire to formulate correctly the rules according to which events occur4 ,a successful theorist should be excessively interested in immediate events1 otherwise he is not at all likely to formulate correctly anything about them4 ,of course1 both sources of science exist in all men4 ,now1 what is this thought organisation which we call science8 ,the first aspect of modern science which struck thoughtful observers was its inductive character4 ,the nature of induction1 its importance1 and the rules of inductive logic have been considered by a long series of thinkers1 especially ,english thinkers3 ,bacon1 ,herschel1 ,j4 ,s4 ,mill1 ,venn1 ,jevons1 and others4 ,i am not going to plunge into an analysis of the process of induction4 ,induction is the machinery and not the product1 and it is the product which ,i want to consider4 ,when we understand the product we shall be in a stronger position to improve the machinery4 ,first1 there is one point which it is necessary to emphasise4 ,there is a tendency in analysing scientific processes to assume a given assemblage of concepts applying to nature1 and to imagine that the discovery of laws of nature consists in selecting by means of inductive logic some one out of a definite set of possible alternative relations which may hold between the things in nature answering to these obvious concepts4 ,in a sense this assumption is fairly correct1 especially in regard to the earlier stages of science4 ,mankind found itself in possession of certain concepts respecting nature--for example1 the concept of fairly permanent material bodies--and proceeded to determine laws which related the corresponding percepts in nature4 ,but the formulation of laws changed the concepts1 sometimes gently by an added precision1 sometimes violently4 ,at first this process was not much noticed1 or at least was felt to be a process curbed within narrow bounds1 not touching fundamental ideas4 ,at the stage where we now are1 the formulation of the concepts can be seen to be as important as the formulation of the empirical laws connecting the events in the universe as thus conceived by us4 ,for example1 the concepts of life1 of heredity1 of a material body1 of a molecule1 of an atom1 of an electron1 of energy1 of space1 of time1 of quantity1 and of number4 ,i am not dogmatising about the best way of getting such ideas straight4 ,certainly it will only be done by those who have devoted themselves to a special study of the facts in question4 ,success is never absolute1 and progress in the right direction is the result of a slow1 gradual process of continual comparison of ideas with facts4 ,the criterion of success is that we should be able to formulate empirical laws1 that is1 statements of relations1 connecting the various parts of the universe as thus conceived1 laws with the property that we can interpret the actual events of our lives as being our fragmentary knowledge of this conceived interrelated whole4 ,but1 for the purpose of science1 what is the actual world8 ,has science to wait for the termination of the metaphysical debate till it can determine its own subject-matter8 ,i suggest that science has a much more homely starting-ground4 ,its task is the discovery of the relations which exist within that flux of perceptions1 sensations1 and emotions which forms our experience of life4 ,the panorama yielded by sight1 sound1 taste1 smell1 touch1 and by more inchoate sensible feelings1 is the sole field of activity4 ,it is in this way that science is the thought organisation of experience4 ,the most obvious aspect of this field of actual experience is its disorderly character4 ,it is for each person a continuum1 fragmentary1 and with elements not clearly differentiated4 ,the comparison of the sensible experiences of diverse people brings its own difficulties4 ,i insist on the radically untidy1 ill-adjusted character of the fields of actual experience from which science starts4 ,to grasp this fundamental truth is the first step in wisdom1 when constructing a philosophy of science4 ,this fact is concealed by the influence of language1 moulded by science1 which foists on us exact concepts as though they represented the immediate deliverances of experience4 ,the result is1 that we imagine that we have immediate experience of a world of perfectly defined objects implicated in perfectly defined events which1 as known to us by the direct deliverance of our senses1 happen at exact instants of time1 in a space formed by exact points1 without parts and without magnitude3 the neat1 trim1 tidy1 exact world which is the goal of scientific thought4 ,my contention is1 that this world is a world of ideas1 and that its internal relations are relations between abstract concepts1 and that the elucidation of the precise connection between this world and the feelings of actual experience is the fundamental question of scientific philosophy4 ,the question which ,i am inviting you to consider is this3 ,how does exact thought apply to the fragmentary1 vague continua of experience8 ,i am not saying that it does not apply3 quite the contrary4 ,but ,i want to know how it applies4 ,the solution ,i am asking for is not a phrase1 however brilliant1 but a solid branch of science1 constructed with slow patience1 showing in detail how the correspondence is effected4 ,the first great steps in the organisation of thought were due exclusively to the practical source of scientific activity1 without any admixture of theoretical impulse4 ,their slow accomplishment was the cause and also the effect of the gradual evolution of moderately rational beings4 ,i mean the formation of the concepts of definite material objects1 of the determinate lapse of time1 of simultaneity1 of recurrence1 of definite relative position1 and of analogous fundamental ideas1 according to which the flux of our experience is mentally arranged for handy reference3 in fact1 the whole apparatus of commonsense thought4 ,consider in your mind some definite chair4 ,the concept of that chair is simply the concept of all the interrelated experiences connected with that chair--namely1 of the experience of the folk who made it1 of the folk who sold it1 of the folk who have seen it or used it1 of the man who is now experiencing a comfortable sense of support1 combined with our expectations of an analogous future1 terminated finally by a different set of experiences when the chair collapses and becomes firewood4 ,the formation of that type of concept was a tremendous job1 and zoologists and geologists tell us that it took many tens of millions of years4 ,i can well believe it4 ,i now emphasise two points4 ,in the first place1 science is rooted in what ,i have just called the whole apparatus of commonsense thought4 ,that is the datum from which it starts1 and to which it must recur4 ,we may speculate1 if it amuses us1 of other beings in other planets who have arranged analogous experiences according to an entirely different conceptual code--namely1 who have directed their chief attention to different relations between their various experiences4 ,but the task is too complex1 too gigantic1 to be revised in its main outlines4 ,you may polish up commonsense1 you may contradict it in detail1 you may surprise it4 ,but ultimately your whole task is to satisfy it4 ,in the second place1 neither commonsense nor science can proceed with their task of thought organisation without departing in some respect from the strict consideration of what is actual in experience4 ,think again of the chair4 ,among the experiences upon which its concept is based1 ,i included our expectations of its future history4 ,i should have gone further and included our imagination of all the possible experiences which in ordinary language we should call perceptions of the chair which might have occurred4 ,this is a difficult question1 and ,i do not see my way through it4 ,but1 at present1 in the construction of a theory of space and of time there seem insuperable difficulties if we refuse to admit ideal experiences4 ,this imaginative perception of experiences1 which1 if they occurred1 would be coherent with our actual experiences1 seems fundamental in our lives4 ,it is neither wholly arbitrary1 nor yet fully determined4 ,it is a vague background which is only made in part definite by isolated activities of thought4 ,consider1 for example1 our thoughts of the unseen flora of ,brazil4 ,ideal experiences are closely connected with our imaginative reproduction of the actual experiences of other people1 and also with our almost inevitable conception of ourselves as receiving our impressions from an external complex reality beyond ourselves4 ,it may be that an adequate analysis of every source and every type of experience yields demonstrative proof of such a reality and of its nature4 ,indeed1 it is hardly to be doubted that this is the case4 ,the precise elucidation of this question is the problem of metaphysics4 ,one of the points which ,i am urging in this address is1 that the basis of science does not depend on the assumption of any of the conclusions of metaphysics2 but that both science and metaphysics start from the same given groundwork of immediate experience1 and in the main proceed in opposite directions on their diverse tasks4 ,for example1 metaphysics inquires how our perceptions of the chair relate us to some true reality4 ,science gathers up these perceptions into a determinate class1 adds to them ideal perceptions of analogous sort1 which under assignable circumstances would be obtained1 and this single concept of that set of perceptions is all that science needs2 unless indeed you prefer that thought find its origin in some legend of those great twin brethren1 the ,cock and ,bull4 ,my immediate problem is to inquire into the nature of the texture of science4 ,science is essentially logical4 ,the nexus between its concepts is a logical nexus1 and the grounds for its detailed assertions are logical grounds4 ,king ,james said1 ,no bishops1 no king4 ,with greater confidence we can say1 ,no logic1 no science4 ,the reason for the instinctive dislike which most men of science feel towards the recognition of this truth is1 ,i think1 the barren failure of logical theory during the past three or four centuries4 ,we may trace this failure back to the worship of authority1 which in some respects increased in the learned world at the time of the ,renaissance4 ,mankind then changed its authority1 and this fact temporally acted as an emancipation4 ,but the main fact1 and we can find complaints#b of it at the very commencement of the modern movement1 was the establishment of a reverential attitude towards any statement made by a classical author4 ,scholars became commentators on truths too fragile to bear translation4 ,a science which hesitates to forget its founders is lost4 ,to this hesitation ,i ascribe the barrenness of logic4 ,another reason for distrust of logical theory and of mathematics is the belief that deductive reasoning can give you nothing new4 ,your conclusions are contained in your premises1 which by hypothesis are known to you4 ,in the first place this last condemnation of logic neglects the fragmentary1 disconnected character of human knowledge4 ,to know one premise on ,monday1 and another premise on ,tuesday1 is useless to you on ,wednesday4 ,science is a permanent record of premises1 deductions1 and conclusions1 verified all along the line by its correspondence with facts4 ,secondly1 it is untrue that when we know the premises we also know the conclusions4 ,in arithmetic1 for example1 mankind are not calculating boys4 ,any theory which proves that they are conversant with the consequences of their assumptions must be wrong4 ,we can imagine beings who possess such insight4 ,but we are not such creatures4 ,both these answers are1 ,i think1 true and relevant4 ,but they are not satisfactory4 ,they are too much in the nature of bludgeons1 too external4 ,we want something more explanatory of the very real difficulty which the question suggests4 ,in fact1 the true answer is embedded in the discussion of our main problem of the relation of logic to natural science4 ,it will be necessary to sketch in broad outline some relevant features of modern logic4 ,in doing so ,i shall try to avoid the profound general discussions and the minute technical classifications which occupy the main part of traditional logic4 ,it is characteristic of a science in its earlier stages--and logic has become fossilised in such a stage--to be both ambitiously profound in its aims and trivial in its handling of details4 ,we can discern four departments of logical theory4 ,by an analogy which is not so very remote ,i will call these departments or sections the arithmetic section1 the algebraic section1 the section of general-function theory1 the analytical section4 ,i do not mean that arithmetic arises in the first section1 algebra in the second section1 and so on2 but the names are suggestive of certain qualities of thought in each section which are reminiscent of analogous qualities in arithmetic1 in algebra1 in the general theory of a mathematical function1 and in the mathematical analysis of the properties of particular functions4 ,the first section--namely1 the arithmetic stage--deals with the relations of definite propositions to each other1 just as arithmetic deals with definite numbers4 ,consider any definite proposition2 call it p4 ,we conceive that there is always another proposition which is the direct contradictory to p2 call it not-p4 ,when we have got two propositions1 p and q1 we can form derivative propositions from them1 and from their contradictories4 ,we can say1 ,at last one of p or q is true1 and perhaps both4 ,let us call this proposition p or q4 ,i may mention as an aside that one of the greatest living philosophers has stated that this use of the word or--namely1 p or q in the sense that either or both may be true--makes him despair of exact expression4 ,we must brave his wrath1 which is unintelligible to me4 ,we have thus got hold of four new propositions1 namely1 p or q1 and not-p or q1 and p or not-q1 and not-p or not-q4 ,call these the set of disjunctive derivatives4 ,there are1 so far1 in all eight propositions1 p1 not-p1 q1 not-q1 and the four disjunctive derivatives4 ,any pair of these eight propositions can be taken1 and substituted for p and q in the foregoing treatment4 ,thus each pair yields eight propositions1 some of which may have been obtained before4 ,by proceeding in this way we arrive at an unending set of propositions of growing complexity1 ultimately derived from the two original propositions p or q4 ,of course1 only a few are important4 ,similarly we can start from three propositions1 p1 q1 r1 or from four propositions1 p1 q1 r1 s1 and so on4 ,any one of the propositions of these aggregates may be true or false4 ,it has no other alternative4 ,whichever it is1 true or false1 call it the truth-value of the proposition4 ,the first section of logical inquiry is to settle what we know of the truth-values of these propositions1 when we know the truth-values of some of them4 ,the inquiry1 so far as it is worth while carrying it1 is not very abstruse1 and the best way of expressing its results is a detail which ,i will not now consider4 ,this inquiry forms the arithmetic stage4 ,the next section of logic is the algebraic stage4 ,now1 the difference between arithmetic and algebra is1 that in arithmetic definite numbers are considered1 and in algebra symbols--namely1 letters--are introduced which stand for any numbers4 ,the idea of a number is also enlarged4 ,these letters1 standing for any numbers1 are called sometimes variables and sometimes parameters4 ,their essential characteristic is that they are undetermined1 unless1 indeed1 the algebraic conditions which they satisfy implicitly determine them4 ,then they are sometimes called unknowns4 ,an algebraic formula with letters is a blank form4 ,it becomes a determinate arithmetic statement when definite numbers are substituted for the letters4 ,the importance of algebra is a tribute to the study of form4 ,consider now the following proposition-- ,the specific heat of mercury is #jjcc4 ,this is a definite proposition which1 with certain limitations1 is true4 ,but the truth-value of the proposition does not immediately concern us4 ,instead of mercury put a mere letter which is the name of some undetermined thing3 we get-- ,the specific heat of x is #jjcc4 ,this is not a proposition2 it has been called by ,russell a propositional function4 ,it is the logical analogy of an algebraic expression4 ,let us write 7x7 for any propositional function4 ,we could also generalise still further1 and say1 ,the specific heat of x is y4 ,we thus get another propositional function1 ,f7x1 y71 of two arguments x and y1 and so on for any number of arguments4 ,now1 consider 7x74 ,there is the range of values of x1 for which 7x7 is a proposition1 true or false4 ,for values of x outside this range1 7x7 is not a proposition at all1 and is neither true nor false4 ,it may have vague suggestions for us1 but it has no unit meaning of definite assertion4 ,for example1 ,the specific heat of water is #jjcc is a proposition which is false2 and-- ,the specific heat of virtue is #jjcc is1 ,i should imagine1 not a proposition at all2 so that it is neither true nor false1 though its component parts raise various associations in our minds4 ,this range of values1 for which 7x7 has sense1 is called the type of the argument x4 ,but there is also a range of values of x for which 7x7 is a true proposition4 ,this is the class of those values of the argument which satisfy 7x74 ,this class may have no members1 or1 in the other extreme1 the class may be the whole type of the arguments4 ,we thus conceive two general propositions respecting the indefinite number of propositions which share in the same logical form1 that is1 which are values of the same propositional function4 ,one of these propositions is1 7x7 yields a true proposition for each value of x of the proper type2 the other proposition is1 ,there is a value of x for which 7x7 is true4 ,given two1 or more1 propositional functions 7x7 and 7x7 with the same argument x1 we form derivative propositional functions1 namely1 7x7 or 7x71 7x7 or not-7x71 and so on with the contradictories1 obtaining1 as in the arithmetical stage1 an unending aggregate of propositional functions4 ,also each propositional function yields two general propositions4 ,the theory of the interconnection between the truth-values of the general propositions arising from any such aggregate of propositional functions forms a simple and elegant chapter of mathematical logic4 ,in this algebraic section of logic the theory of types crops up1 as we have already noted4 ,it cannot be neglected without the introduction of error4 ,its theory has to be settled at least by some safe hypothesis1 even if it does not go to the philosophic basis of the question4 ,this part of the subject is obscure and difficult1 and has not been finally elucidated1 though ,russell's brilliant work has opened out the subject4 ,the final impulse to modern logic comes from the independent discovery of the importance of the logic variable by ,frege and ,peano4 ,frege went further than ,peano1 but by an unfortunate symbolism rendered his work so obscure that no one fully recognised his meaning who had not found it out for himself4 ,but the movement has a large history reaching back to ,leibniz and even to ,aristotle4 ,among ,english contributors are ,de ,morgan1 ,boole1 and ,sir ,alfred ,kempe2 their work is of the first rank4 ,the third logical section is the stage of general-function theory4 ,in logical language1 we perform in this stage the transition from intension to extension1 and investigate the theory of denotation4 ,take the propositional function1 7x74 ,there is the class1 or range of values for x1 whose members satisfy 7x74 ,but the same range may be the class whose members satisfy another propositional function 7x74 ,it is necessary to investigate how to indicate the class by a way which is indifferent as between the various propositional functions which are satisfied by any member of it1 and of it only4 ,what has to be done is to analyse the nature of propositions about a class--namely1 those propositions whose truth-values depend on the class itself and not on the particular meaning by which the class is indicated4 ,furthermore1 there are propositions about alleged individuals indicated by descriptive phrases3 for example1 propositions about the present ,king of ,england1 who does exist1 and the present ,emperor of ,brazil1 who does not exist4 ,more complicated1 but analogous1 questions involving propositional functions of two variables involve the notion of correlation1 just as functions of one argument involve classes4 ,similarly functions of three arguments yield three-cornered correlations1 and so on4 ,this logical section is one which ,russell has made peculiarly his own by work which must always remain fundamental4 ,i have called this the section of functional theory1 because its ideas are essential to the construction of logical denoting functions which include as a special case ordinary mathematical functions1 such as sine1 logarithm1 etc4 ,in each of these three stages it will be necessary gradually to introduce an appropriate symbolism1 if we are to pass on to the fourth stage4 ,the fourth logical section1 the analytic stage1 is concerned with the investigation of the properties of special logical constructions1 that is1 of classes and correlations of special sorts4 ,the whole of mathematics is included here4 ,so the section is a large one4 ,in fact1 it is mathematics1 neither more nor less1 but it includes an analysis of mathematical ideas not hitherto included in the scope of that science1 nor1 indeed1 contemplated at all4 ,the essence of this stage is construction4 ,it is by means of suitable constructions that the great framework of applied mathematics1 comprising the theories of number1 quantity1 time1 and space1 is elaborated4 ,it is impossible1 even in brief outline1 to explain how mathematics is developed from the concepts of class and correlation1 including many-cornered correlations1 which are established in the third section4 ,i can only allude to the headings of the process1 which is fully developed in the work1 ,principia ,mathematica1 by ,mr4 ,russell and myself4 ,there are in this process of development seven special sorts of correlations which are of peculiar interest4 ,the first sort comprises one-to-many1 many-to-one1 and one-to-one correlations4 ,the second sort comprises serial relations1 that is1 correlations by which the members of some field are arranged in serial order1 so that1 in the sense defined by the relation1 any member of the field is either before or after any other member4 ,the third class comprises inductive relations1 that is1 correlations on which the theory of mathematical induction depends4 ,the fourth class comprises selective relations1 which are required for the general theory of arithmetic operations1 and elsewhere4 ,it is in connection with such relations that the famous multiplicative axiom arises for consideration4 ,the fifth class comprises vector relations1 from which the theory of quantity arises4 ,the sixth class comprises ratio relations1 which interconnect number and quantity4 ,the seventh class comprises three-cornered and four-cornered relations which occur in geometry4 ,a bare enumeration of technical names1 such as the above1 is not very illuminating1 though it may help to a comprehension of the demarcations of the subject4 ,please remember that the names are technical names1 meant1 no doubt1 to be suggestive1 but used in strictly defined senses4 ,we have suffered much from critics who consider it sufficient to criticise our procedure on the slender basis of a knowledge of the dictionary meanings of such terms4 ,for example1 a one-to-one correlation depends on the notion of a class with only one member1 and this notion is defined without appeal to the concept of the number one4 ,the notion of diversity is all that is wanted4 ,thus the class has only one member1 if 7#a7 the class of values of x which satisfies the propositional function1 x is not a member of 1 is not the whole type of relevant values of x1 and if 7#b7 the propositional function1 x and y are members of 1 and x is diverse from y is false1 whatever be the values of x and y in the relevant type4 ,analogous procedures are obviously possible for higher finite cardinal members4 ,thus1 step by step1 the whole cycle of current mathematical ideas is capable of logical definition4 ,the process is detailed and laborious1 and1 like all science1 knows nothing of a royal road of airy phrases4 ,the essence of the process is1 first1 to construct the notion in terms of the forms of propositions1 that is1 in terms of the relevant propositional functions1 and secondly1 to prove the fundamental truths which hold about the notion by reference to the results obtained in the algebraic section of logic4 ,it will be seen that in this process the whole apparatus of special indefinable mathematical concepts1 and special a priori mathematical premises1 respecting number1 quantity1 and space1 has vanished4 ,mathematics is merely an apparatus for analysing the deductions which can be drawn from any particular premises1 supplied by commonsense1 or by more refined scientific observation1 so far as these deductions depend on the forms of the propositions4 ,propositions of certain forms are continually occurring in thought4 ,our existing mathematics is the analysis of deductions which concern those forms and in some way are important1 either from practical utility or theoretical interest4 ,here ,i am speaking of the science as it in fact exists4 ,a theoretical definition of mathematics must include in its scope any deductions depending on the mere forms of propositions4 ,but1 of course no one would wish to develop that part of mathematics which in no sense is of importance4 ,this hasty summary of logical ideas suggests some reflections4 ,the question arises1 ,how many forms of propositions are there8 ,the answer is1 ,an unending number4 ,the reason for the supposed sterility of logical science can thus be discerned4 ,aristotle founded the science by conceiving the idea of the form of a proposition1 and by conceiving deduction as taking place in virtue of the forms4 ,but he confined propositions to four forms1 now named ,a1 ,i1 ,e1 ,o4 ,so long as logicians were obsessed by this unfortunate restriction1 real progress was impossible4 ,again1 in their theory of form1 both ,aristotle and subsequent logicians came very near to the theory of the logical variable4 ,but to come very near to a true theory1 and to grasp its precise application1 are two very different things1 as the history of science teaches us4 ,everything of importance has been said before by somebody who did not discover it4 ,again1 one reason why logical deductions are not obvious is1 that logical form is not a subject which ordinarily enters into thought4 ,commonsense deduction probably moves by blind instinct from concrete proposition to concrete proposition1 guided by some habitual association of ideas4 ,thus commonsense fails in the presence of a wealth of material4 ,a more important question is the relation of induction1 based on observation1 to deductive logic4 ,there is a tradition of opposition between adherents of induction and of deduction4 ,in my view1 it would be just as sensible for the two ends of a worm to quarrel4 ,both observation and deduction are necessary for any knowledge worth having4 ,we cannot get at an inductive law without having recourse to a propositional function4 ,for example1 take the statement of observed fact1 ,this body is mercury1 and its specific heat is #jjcc4 ,the propositional function is formed1 ,either x is not mercury1 or its specific heat is #jjcc4 ,the inductive law is the assumption of the truth of the general proposition1 that the above propositional function is true for every value of x in the relevant type4 ,but it is objected that this process and its consequences are so simple that an elaborate science is out of place4 ,in the same way1 a ,british sailor knows the salt sea when he sails over it4 ,what1 then1 is the use of an elaborate chemical analysis of sea-water8 ,there is the general answer1 that you cannot know too much of methods which you always employ2 and there is the special answer1 that logical forms and logical implications are not so very simple1 and that the whole of mathematics is evidence to this effect4 ,one great use of the study of logical method is not in the region of elaborate deduction1 but to guide us in the study of the formation of the main concepts of science4 ,consider geometry1 for example4 ,what are the points which compose space8 ,euclid tells us that they are without parts and without magnitude4 ,but how is the notion of a point derived from the sense-perceptions from which science starts8 ,certainly points are not direct deliverances of the senses4 ,here and there we may see or unpleasantly feel something suggestive of a point4 ,but this is a rare phenomenon1 and certainly does not warrant the conception of space as composed of points4 ,our knowledge of space properties is not based on any observations of relations between points4 ,it arises from experience of relations between bodies4 ,now a fundamental space-relation between bodies is that one body may be part of another4 ,we are tempted to define the whole and part relation by saying that the points occupied by the part are some of the points occupied by the whole4 ,but whole and part being more fundamental than the notion of point1 this definition is really circular and vicious4 ,we accordingly ask whether any other definition of spatial whole and part can be given4 ,i think that it can be done in this way1 though1 if ,i be mistaken1 it is unessential to my general argument4 ,we have come to the conclusion that an extended body is nothing else than the class of perception of it by all its percipients1 actual or ideal4 ,of course1 it is not any class of perceptions1 but a certain definite sort of class which ,i have not defined here1 except by the vicious method of saying that they are perceptions of body4 ,now1 the perceptions of a part of a body are among the perceptions which compose the whole body4 ,thus two bodies a and b are both classes of perceptions2 and b is part of a when the class which is b is contained in the class which is a4 ,it immediately follows from the logical form of this definition that if b is part of a1 and c is part of b1 then c is part of a4 ,thus the relation whole to part is transitive4 ,again1 it will be convenient to allow that a body is part of itself4 ,this is a mere question of how you draw the definition4 ,with this understanding1 the relation is reflexive4 ,finally1 if a is part of b1 and b is part of a1 then a and b must be identical4 ,these properties of whole and part are not fresh assumptions1 they follow from the logical form of our definition4 ,one assumption has to be made if we assume the ideal infinite divisibility of space4 ,namely1 we assume that every class of perceptions which is an extended body contains other classes of perceptions which are extended bodies diverse from itself4 ,this assumption makes rather a large draft on the theory of ideal perceptions4 ,geometry vanishes unless in some form you make it4 ,the assumption is not peculiar to my exposition4 ,it is then possible to define what we mean by a point4 ,a point is the class of extended objects which1 in ordinary language1 contain that point4 ,the definition1 without presupposing the idea of a point1 is rather elaborate1 and ,i have not now time for its statement4 ,the advantage of introducing points into geometry is the simplicity of the logical expression of their mutual relations4 ,for science1 simplicity of definition is of slight importance1 but simplicity of mutual relations is essential4 ,another example of this law is the way physicists and chemists have dissolved the simple idea of an extended body1 say of a chair1 which a child understands1 into a bewildering notion of a complex dance of molecules and atoms and electrons and waves of light4 ,they have thereby gained notions with simpler logical relations4 ,space as thus conceived is the exact formulation of the properties of the apparent space of the commonsense world of experience4 ,it is not necessarily the best mode of conceiving the space of the physicist4 ,the one essential requisite is that the correspondence between the commonsense world in its space and the physicists' world in its space should be definite and reciprocal4 ,i will now break off the exposition of the function of logic in connection with the science of natural phenomena4 ,i have endeavoured to exhibit it as the organising principle1 analysing the derivation of the concepts from the immediate phenomena1 examining the structure of the general propositions which are the assumed laws of nature1 establishing their relations to each other in respect to reciprocal implications1 deducing the phenomena we may expect under given circumstances4 ,logic1 properly used1 does not shackle thought4 ,it gives freedom1 and above all1 boldness4 ,illogical thought hesitates to draw conclusions1 because it never knows either what it means1 or what it assumes1 or how far it trusts its own assumptions1 or what will be the effect of any modification of assumptions4 ,also the mind untrained in that part of constructive logic which is relevant to the subject in hand will be ignorant of the sort of conclusions which follow from various sorts of assumptions1 and will be correspondingly dull in divining the inductive laws4 ,the fundamental training in this relevant logic is1 undoubtedly1 to ponder with an active mind over the known facts of the case1 directly observed4 ,but where elaborate deductions are possible1 this mental activity requires for its full exercise the direct study of the abstract logical relations4 ,this is applied mathematics4 ,neither logic without observation1 nor observation without logic1 can move one step in the formation of science4 ,we may conceive humanity as engaged in an internecine conflict between youth and age4 ,youth is not defined by years but by the creative impulse to make something4 ,the aged are those who1 before all things1 desire not to make a mistake4 ,logic is the olive branch from the old to the young1 the wand which in the hands of youth has the magic property of creating science4 ,,footnotes3 ,footnote #b3 ,e4g4 in #aeea by ,italian schoolmen2 cf4 ,sarpi's ,history of the ,council of ,trent1 under that date4 ,,chapter ,,vii ,,the ,,anatomy ,,of ,,some ,,scientific ,,ideas ,i4 ,fact ,,the characteristic of physical science is1 that it ignores all judgments of value3 for example1 sthetic or moral judgments4 ,it is purely matter-of-fact1 and this is the sense in which we must interpret the sonorous phrase1 ,man1 the servant and the minister of ,nature4 ,the sphere of thought which is thus left is even then too wide for physical science4 ,it would include ,ontology1 namely1 the determination of the nature of what truly exists2 in other words1 ,metaphysics4 ,from an abstract point of view this exclusion of metaphysical inquiry is a pity4 ,such an inquiry is a necessary critique of the worth of science1 to tell us what it all comes to4 ,the reasons for its careful separation from scientific thought are purely practical2 namely1 because we can agree about science--after due debate--whereas in respect to metaphysics debate has hitherto accentuated disagreement4 ,these characteristics of science and metaphysics were unexpected in the early days of civilised thought4 ,the ,greeks thought that metaphysics was easier than physics1 and tended to deduce scientific principles from a priori conceptions of the nature of things4 ,they were restrained in this disastrous tendency by their vivid naturalism1 their delight in first-hand perception4 ,medival ,europe shared the tendency without the restraint4 ,it is possible that some distant generations may arrive at unanimous conclusions on ontological questions1 whereas scientific progress may have led to ingrained opposing veins of thought which can neither be reconciled nor abandoned4 ,in such times metaphysics and physical science will exchange their rles4 ,meanwhile we must take the case as we find it4 ,but a problem remains4 ,how can mankind agree about science without a preliminary determination of what really is8 ,the answer must be found in an analysis of the facts which form the field of scientific activity4 ,mankind perceives1 and finds itself thinking about its perceptions4 ,it is the thought that matters and not that element of perception which is not thought4 ,when the immediate judgment has been formed--,hullo1 red6--it does not matter if we can imagine that in other circumstances--in better circumstances1 perhaps--the judgment would have been--,hullo1 blue6--or even--,hullo1 nothing6 ,for all intents and purposes1 at the time it was red4 ,everything else is hypothetical reconstruction4 ,the field of physical science is composed of these primary thoughts1 and of thoughts about these thoughts4 ,but--to avoid confusion--a false simplicity has been introduced above into the example given of a primary perceptive thought4 ,hullo1 red6 is not really a primary perceptive thought1 though it often is the first thought which finds verbal expression even silently in the mind4 ,nothing is in isolation4 ,the perception of red is of a red object in its relations to the whole content of the perceiving consciousness4 ,among the most easily analysed of such relations are the space relations4 ,again the red object is in immediate perception nothing else than a red object4 ,it is better termed an object of redness4 ,thus a better approximation to an immediate perceptive judgment is1 ,hullo1 object of redness there6 ,but1 of course1 in this formulation other more complex relations are omitted4 ,this tendency towards a false simplicity in scientific analysis1 to an excessive abstraction1 to an over-universalising of universals1 is derived from the earlier metaphysical stage4 ,it arises from the implicit belief that we are endeavouring to qualify the real with appropriate adjectives4 ,in conformity with this tendency we think1 this real thing is red4 ,whereas our true goal is to make explicit our perception of the apparent in terms of its relations4 ,what we perceive is redness related to other apparents4 ,our object is the analysis of the relations4 ,one aim of science is the harmony of thought1 that is1 to secure that judgments which are logical contraries should not be thought-expressions of consciousness4 ,another aim is the extension of such harmonised thought4 ,some thoughts arise directly from sense-presentation1 and are part of the state of consciousness which is perception4 ,such a thought is1 ,an object of redness is there4 ,but in general the thought is not verbal1 but is a direct apprehension of qualities and relations within the content of consciousness4 ,amid such thoughts there can be no lack of harmony4 ,for direct apprehension is in its essence unique1 and it is impossible to apprehend an object as both red and blue4 ,subsequently it may be judged that if other elements of the consciousness had been different1 the apprehension would have been of a blue object4 ,then--under certain circumstances--the original apprehension will be called an error4 ,but for all that the fact remains1 there was an apprehension of a red object4 ,when we speak of sense-presentation1 we mean these primary thoughts essentially involved in its perception4 ,but there are thoughts about thoughts1 and thoughts derived from other thoughts4 ,these are secondary thoughts4 ,at this point it is well explicitly to discriminate between an actual thought-expression1 namely1 a judgment actually made1 and a mere proposition which is a hypothetical thought-expression1 namely1 an imagined possibility of thought-expression4 ,note that the actual complete thought-content of the consciousness is explicitly neither affirmed or denied4 ,it is just what is thought4 ,thus1 to think two and two make four is distinct from affirming that two and two make four4 ,in the first case the proposition is the thought-expression1 in the second case the affirmation of the proposition is the thought-expression1 and the proposition has been degraded to a mere proposition1 namely1 to a hypothetical thought-expression which is reflected upon4 ,a distinction is sometimes made between facts and thoughts4 ,so far as physical science is concerned1 the facts are thoughts1 and thoughts are facts4 ,namely1 the facts of sense-presentation as they affect science are those elements in the immediate apprehensions which are thoughts4 ,also1 actual thought-expressions1 primary or secondary1 are the material facts which science interprets4 ,the distinction that facts are given1 but thoughts are free1 is not absolute4 ,we can select and modify our sense-presentation1 so that facts--in the narrower sense of immediate apprehension of sense-presentation--are to some degree subject to volition4 ,again1 our stream of thought-expression is only partially modified by explicit volition4 ,we can choose our physical experience1 and we find ourselves thinking2 namely1 on the one hand there is selection amid the dominant necessity of sense1 and on the other hand1 the thought-content of consciousness 7so far as secondary thoughts are concerned7 is not wholly constituted by the selection of will4 ,thus1 on the whole there is a large primary region of secondary thought1 as well as of the primary thoughts of sense-presentation1 which is given in type4 ,that is the way in which we do think of things1 not wholly from any abstract necessity1 so far as we know1 but because we have inherited the method from an environment4 ,it is the way we find ourselves thinking1 a way which can only be fundamentally laid aside by an immense effort1 and then only for isolated short periods of time4 ,this is what ,i have called the whole apparatus of commonsense thought4 ,it is this body of thought which is assumed in science4 ,it is a way of thinking rather than a set of axioms4 ,it is1 in fact1 the set of concepts which commonsense has found useful in sorting out human experience4 ,it is modified in detail1 but assumed in gross4 ,the explanations of science are directed to finding conceptions and propositions concerning nature which explain the importance of these common sense notions4 ,for example1 a chair is a common sense notion1 molecules and electrons explain our vision of chairs4 ,now science aims at harmonising our reflective and derivative thoughts with the primary thoughts involved in the immediate apprehension of sense-presentation4 ,it also aims at producing such derivative thoughts1 logically knit together4 ,this is scientific theory2 and the harmony to be achieved is the agreement of theory with observation1 which is the apprehension of sense-presentation4 ,thus there is a twofold scientific aim3 7#a7 the production of theory which agrees with experience2 and 7#b7 the explanation of commonsense concepts of nature1 at least in their main outlines4 ,this explanation consists in the preservation of the concepts in a scientific theory of harmonised thought4 ,it is not asserted that this is what scientists in the past meant to achieve1 or thought that they could achieve4 ,it is suggested as the actual result of scientific effort1 so far as that effort has had any measure of success4 ,in short1 we are here discussing the natural history of ideas and not volitions of scientists4 ,,ii4 ,objects ,we perceive things in space4 ,for example1 among such things are dogs1 chairs1 curtains1 drops of water1 gusts of air1 flames1 rainbows1 chimes of bells1 odours1 aches and pains4 ,there is a scientific explanation of the origin of these perceptions4 ,this explanation is given in terms of molecules1 atoms1 electrons1 and their mutual relations1 in particular of their space-relations1 and waves of disturbance of these space-relations which are propagated through space4 ,the primary elements of the scientific explanation--molecules1 etc4--are not the things directly perceived4 ,for example1 we do not perceive a wave of light2 the sensation of sight is the resultant effect of the impact of millions of such waves through a stretch of time4 ,thus the object directly perceived corresponds to a series of events in the physical world1 events which are prolonged through a stretch of time4 ,nor is it true that a perceived object always corresponds to the same group of molecules4 ,after a few years we recognise the same cat1 but we are thereby related to different molecules4 ,again1 neglecting for a moment the scientific explanation1 the perceived object is largely the supposition of our imagination4 ,when we recognised the cat1 we also recognised that it was glad to see us4 ,but we merely heard its mewing1 saw it arch its back1 and felt it rubbing itself against us4 ,we must distinguish1 therefore1 between the many direct objects of sense1 and the single indirect object of thought which is the cat4 ,thus1 when we say that we perceived the cat and understood its feelings1 we mean that we heard a sense-object of sound1 that we saw a sense-object of sight1 that we felt a sense-object of touch1 and that we thought of a cat and imagined its feelings4 ,sense-objects are correlated by time-relations and space-relations4 ,three simultaneous sense-objects which are also spatially coincident1 are combined by thought into the perception of one cat4 ,such combination of sense-objects is an instinctive immediate judgment in general without effort of reasoning4 ,sometimes only one sense-object is present4 ,for example1 we hear mewing and say there must be a cat in the room4 ,the transition from the sense-object to the cat has then been made1 by deliberate ratiocination4 ,even the concurrence of sense-objects may provoke such a self-conscious effort4 ,for example1 in the dark we feel something1 and hear mewing from the same place1 and think1 ,surely this is a cat4 ,sight is more bold2 when we see a cat1 we do not think further4 ,we identify the sight with the cat1 whereas the cat and the mew are separate4 ,but such immediate identification of a sight object and an object of thought may lead to error2 the birds pecked at the grapes of ,apelles4 ,a single sense-object is a complex entity4 ,the sight-object of a tile on the hearth may remain unchanged as we watch it in a steady light1 remaining ourselves unchanged in position4 ,even then it is prolonged in time1 and has parts in space4 ,also it is somewhat arbitrarily distinguished from a larger whole of which it forms part4 ,but the glancing fire-light and a change in our position alters the sight-object4 ,we judge that the tile thought-object remains unchanged4 ,the sight-object of the coal on the fire gradually modifies1 though within short intervals it remains unchanged4 ,we judge that the coal thought-object is changing4 ,the flame is never the same1 and its shape is only vaguely distinguishable4 ,we conclude that a single self-identical sight-object is already a phantasy of thought4 ,consider the unchanging sight-object of the tile1 as we remain still in a steady light4 ,now a sense-object perceived at one time is a distinct object from a sense-object seen at another time4 ,thus the sight of the tile at noon is distinct from its sight at #ab4cj4 ,but there is no such thing as a sense-object at an instant4 ,as we stare at the tile1 a minute1 or a second1 or a tenth of a second1 has flown by3 essentially there is a duration4 ,there is a stream of sight1 and we can distinguish its parts4 ,but the parts also are streams1 and it is only in thought that the stream separates into a succession of elements4 ,the stream may be steady as in the case of the unchanging sight-tile1 or may be turbulent as in the case of the glancing sight-flame4 ,in either case a sight-object is some arbitrarily small part of the stream4 ,again1 the stream which forms the succession of sight-tiles is merely a distinguishable part of the whole stream of sight-presentation4 ,so1 finally1 we conceive ourselves each experiencing a complete time-flux 7or stream7 of sense-presentation4 ,this stream is distinguishable into parts4 ,the grounds of distinction are differences of sense--including within that term1 differences of types of sense1 and differences of quality and of intensity within the same type of sense--and differences of time-relations1 and differences of space-relations4 ,also the parts are not mutually exclusive and exist in unbounded variety4 ,the time-relation between the parts raises the questions of memory and recognition1 subjects too complex for discussion here4 ,one remark must be made4 ,if it be admitted1 as stated above1 that we live in durations and not in instants1 namely1 that the present essentially occupies a stretch of time1 the distinction between memory and immediate presentation cannot be quite fundamental2 for always we have with us the fading present as it becomes the immediate past4 ,this region of our consciousness is neither pure memory nor pure immediate presentation4 ,anyhow1 memory is also a presentation in consciousness4 ,another point is to be noted in connection with memory4 ,there is no directly perceived time-relation between a present event and a past event4 ,the present event is only related to the memory of the past event4 ,but the memory of a past event is itself a present element in consciousness4 ,we assert the principle that directly perceived relations can only exist between elements of consciousness1 both in that present during which the perception occurs4 ,all other relations between elements of perception are inferential constructions4 ,it thus becomes necessary to explain how the time stream of events establishes itself in thought1 and how the apparent world fails to collapse into one single present4 ,the solution of the difficulty is arrived at by observing that the present is itself a duration1 and therefore includes directly perceived time-relations between events contained within it4 ,in other words we put the present on the same footing as the past and the future in respect to the inclusion within it of antecedent and succeeding events1 so that past1 present1 and future are in this respect exactly analogous ideas4 ,thus there will be two events a and b1 both in the same present1 but the event a will be directly perceived to precede the event b4 ,again time flows on1 and the event a fades into the past1 and in the new present duration events b and c occur1 event b preceding event c1 also in the same present duration there is the memory of the time-relation between a and b4 ,then by an inferential construction the event a in the past precedes the event c in the present4 ,by proceeding according to this principle the time-relations between elements of consciousness1 not in the same present1 are established4 ,the method of procedure here explained is a first example of what we will call the ,principle of ,aggregation4 ,this is one of the fundamental principles of mental construction according to which our conception of the external physical world is constructed4 ,other examples will later on be met with4 ,the space-relations between the parts are confused and fluctuating1 and in general lack determinate precision4 ,the master-key by which we confine our attention to such parts as possess mutual relations sufficiently simple for our intellects to consider is the principle of convergence to simplicity with diminution of extent4 ,we will call it the principle of convergence4 ,this principle extends throughout the whole field of sense-presentation4 ,the first application of the principle occurs in respect to time4 ,the shorter the stretch of time1 the simpler are the aspects of the sense-presentation contained within it4 ,the perplexing effects of change are diminished and in many cases can be neglected4 ,nature has restricted the acts of thought which endeavour to realise the content of the present1 to stretches of time sufficiently short to secure this static simplicity over the greater part of the sense-stream4 ,spatial relations become simplified within the approximately static sense-world of the short time4 ,a further simplicity is gained by partitioning this static world into parts of restricted space-content4 ,the various parts thus obtained have simpler mutual space-relations1 and again the principle of convergence holds4 ,finally1 the last simplicity is obtained by partitioning the parts1 already restricted as to space and time1 into further parts characterised by homogeneity in type of sense1 and homogeneity in quality and intensity of sense4 ,these three processes of restriction yield1 finally1 the sense-objects which have been mentioned above4 ,thus the sense-object is the result of an active process of discrimination made in virtue of the principle of convergence4 ,it is the result of the quest for simplicity of relations within the complete stream of sense-presentation4 ,the thought-objects of perception are instances of a fundamental law of nature1 the law of objective stability4 ,it is the law of the coherence of sense-objects4 ,this law of stability has an application to time and an application to space2 also it must be applied in conjunction with that other law1 the principle of convergence to simplicity from which sense-objects are derived4 ,some composite partial streams of sense-presentation can be distinguished with the following characteristics3 7#a7 the time-succession of sense-objects1 belonging to a single sense1 involved in any such a composite partial stream1 is composed of very similar objects whose modifications increase only gradually1 and thus forms a homogeneous component stream within the composite stream2 7#b7 the space-relations of those sense-objects 7of various senses7 of such a composite stream which are confined within any sufficiently short time are identical so far as they are definitely apprehended1 and thus these various component streams1 each homogeneous1 cohere to form the whole composite partial stream2 7#c7 there are other sense-presentations occurring in association with that composite partial stream which can be determined by rules derived from analogous composite partial streams1 with other space and time relations1 provided that the analogy be sufficiently close4 ,call these the associated sense-presentations4 ,a partial stream of this sort1 viewed as a whole1 is here called a first crude thought-object of perception4 ,for example1 we look at an orange for half a minute1 handle it1 and smell it1 note its position in the fruit-basket1 and then turn away4 ,the stream of sense-presentation of the orange during that half-minute is a first crude thought-object of perception4 ,among the associated sense presentations are those of the fruit-basket which we conceive as supporting the orange4 ,the essential ground of the association of sense-objects of various types1 perceived within one short duration1 into a first crude thought-object of perception is the coincidence of their space-relations1 that is1 in general an approximate coincidence of such relations perhaps only vaguely apprehended4 ,thus coincident space-relations associate sense-objects into a first crude thought-object1 and diverse space-relations dissociate sense-objects from aggregation into a first crude thought-object4 ,in respect to some groups of sense-objects the association may be an immediate judgment devoid of all inference1 so that the primary perceptual thought is that of the first crude thought-object1 and the separate sense-objects are the result of reflective analysis acting on memory4 ,for example sense-objects of sight and sense-objects of touch are often thus primarily associated and only secondarily dissociated in thought4 ,but sometimes the association is wavering and indeterminate1 for example1 that between the sound-object of the mew of the cat and the sight-object of the cat4 ,thus to sum up1 the partial stream of sense-perceptions coalesces into that first crude thought-object of perception which is the momentary cat because the sense-perceptions belonging to this stream are in the same place1 but equally it would be true to say that they are in the same place because they belong to the same momentary cat4 ,this analysis of the complete stream of sense-presentation in any small present duration into a variety of first crude thought-objects only partially fits the facts2 for one reason because many sense-objects1 such as sound for instance1 have vague and indeterminate space-relations1 for example vaguely those space-relations which we associate with our organs of sense and also vaguely those of the origin from which 7in the scientific explanation7 they proceed4 ,the procedure by which the orange of half a minute is elaborated into the orange in the ordinary sense of the term involves in addition the two principles of aggregation and of hypothetical sense-presentation4 ,the principle of aggregation1 as here employed1 takes the form that many distinct first crude thought-objects of perception are conceived as one thought-object of perception1 if the many partial streams forming these objects are sufficiently analogous1 if their times of occurrence are distinct1 and if the associated sense-presentations are sufficiently analogous4 ,for example1 after leaving the orange1 in five minutes we return4 ,a new first crude thought-object of perception presents itself to us1 indistinguishable from the half-minute orange we previously experienced2 it is in the same fruit-basket4 ,we aggregate the two presentations of an orange into the same orange4 ,by such aggregations we obtain second crude thought-objects of perception4 ,but however far we can proceed with aggregation of this type1 the orange is more than that4 ,for example1 what do we mean when we say1 ,the orange is in the cupboard1 if ,tom has not eaten it8 ,the world of present fact is more than a stream of sense-presentation4 ,we find ourselves with emotions1 volitions1 imaginations1 conceptions1 and judgments4 ,no factor which enters into consciousness is by itself or even can exist in isolation4 ,we are analysing certain relations between sense-presentation and other factors of consciousness4 ,hitherto we have taken into account merely the factors of concept and judgment4 ,imagination is necessary to complete the orange1 namely1 the imagination of hypothetical sense-presentations4 ,it is beside the point to argue whether we ought to have such imaginations1 or to discuss what are the metaphysical truths concerning reality to which they correspond4 ,we are here only concerned with the fact that such imaginations exist and essentially enter into the formation of the concepts of the thought-objects of perception which are the first data of science4 ,we conceive the orange as a permanent collection of sense-presentations existing as if they were an actual element in our consciousness1 which they are not4 ,the orange is thus conceived as in the cupboard with its shape1 odour1 colour1 and other qualities4 ,namely1 we imagine hypothetical possibilities of sense-presentation1 and conceive their want of actuality in our consciousness as immaterial to their existence in fact4 ,the fact which is essential for science is our conception2 its meaning in regard to the metaphysics of reality is of no scientific importance1 so far as physical science is concerned4 ,the orange completed in this way is the thought-object of perception4 ,it must be remembered that the judgments and concepts arising in the formation of thought-objects of perception are in the main instinctive judgments1 and instinctive concepts1 and are not concepts and judgments consciously sought for and consciously criticised before adoption4 ,their adoption is facilitated by and interwoven with the expectation of the future in which the hypothetical passes into the actual1 and also with the further judgment of the existence of other consciousnesses1 so that much that is hypothetical to one consciousness is judged to be actual to others4 ,the thought-object of perception is1 in fact1 a device to make plain to our reflective consciousness relations which hold within the complete stream of sense-presentation4 ,concerning the utility of this weapon there can be no question2 it is the rock upon which the whole structure of commonsense thought is erected4 ,but when we consider the limits of its application the evidence is confused4 ,a great part of our sense-presentation can be construed as perception of various persistent thought-objects4 ,but hardly at any time can the sense-presentations be construed wholly in that way4 ,sights lend themselves easily to this construction1 but sight can be baffled3 for example1 consider reflections in looking-glasses1 apparently bent sticks half in and half out of water1 rainbows1 brilliant patches of light which conceal the object from which they emanate1 and many analogous phenomena4 ,sound is more difficult2 it tends largely to disengage itself from any such object4 ,for example1 we see the bell1 but we hear the sound which comes from the bell2 yet we also say that we hear the bell4 ,again1 a toothache is largely by itself1 and is only indirectly a perception of the nerve of the tooth4 ,illustrations to the same effect can be accumulated from every type of sensation4 ,another difficulty arises from the fact of change4 ,the thought-object is conceived as one thing1 wholly actual at each instant4 ,but since the meat has been bought it has been cooked1 the grass grows and then withers1 the coal burns in the fire1 the pyramids of ,egypt remain unchanged for ages1 but even the pyramids are not wholly unchanged4 ,the difficulty of change is merely evaded by affixing a technical ,latin name to a supposed logical fallacy4 ,a slight cooking leaves the meat the same object1 but two days in the oven burns it to a cinder4 ,when does the meat cease to be8 ,now the chief use of the thought-object is the concept of it as one thing1 here and now1 which later can be recognised1 there and then4 ,this concept applies sufficiently well to most things for short times1 and to many things for long times4 ,but sense-presentation as a whole entirely refuses to be patient of the concept4 ,we have now come to the reflective region of explanation1 which is science4 ,a great part of the difficulty is at once removed by applying the principle of convergence to simplicity4 ,we habitually make our thought-objects too large2 we should think in smaller parts4 ,for example1 the ,sphinx has changed by its nose becoming chipped1 but by proper inquiry we could find the missing part in some private house of ,western ,europe or ,northern ,america4 ,thus1 either part1 the rest of the ,sphinx or the chip1 regains its permanence4 ,furthermore1 we enlarge this explanation by conceiving parts so small that they can only be observed under the most favourable circumstances4 ,this is a wide extension of the principle of convergence in its application to nature2 but it is a principle amply supported by the history of exact observation4 ,thus1 change in thought-objects of perception is largely explained as a disintegration into smaller parts1 themselves thought-objects of perception4 ,the thought-objects of perception which are presupposed in the common thought of civilised beings are almost wholly hypothetical4 ,the material universe is largely a concept of the imagination which rests on a slender basis of direct sense-presentation4 ,but none the less it is a fact2 for it is a fact that actually we imagine it4 ,thus it is actual in our consciousness just as sense-presentation also is actual there4 ,the effort of reflective criticism is to make these two factors in our consciousness agree where they are related1 namely1 to construe our sense-presentation as actual realisation of the hypothetical thought-objects of perception4 ,the wholesale employment of purely hypothetical thought-objects of perception enables science to explain some of the stray sense-objects which cannot be construed as perceptions of a thought-object of perception3 for example1 sounds4 ,but the phenomena as a whole defy explanation on these lines until a further fundamental step is taken1 which transforms the whole concept of the material universe4 ,namely1 the thought-object of perception is superseded by the thought-object of science4 ,the thought-objects of science are molecules1 atoms1 and electrons4 ,the peculiarity of these objects is that they have shed all the qualities which are capable of direct sense-representation in consciousness4 ,they are known to us only by their associated phenomena1 namely1 series of events in which they are implicated are represented in our consciousness by sense-presentations4 ,in this way1 the thought-objects of science are conceived as the causes of sense-representation4 ,the transition from thought-objects of perception to thought-objects of science is decently veiled by an elaborate theory concerning primary and secondary qualities of bodies4 ,this device1 by which sense-presentations are represented in thought as our perception of events in which thought-objects of science are implicated1 is the fundamental means by which a bridge is formed between the fluid vagueness of sense and the exact definition of thought4 ,in thought a proposition is either true or false1 an entity is exactly what it is1 and relations between entities are expressible 7in idea7 by definite propositions about distinctly conceived entities4 ,sense-perception knows none of these things1 except by courtesy4 ,accuracy essentially collapses at some stage of inquiry4 ,,iii4 ,time and ,space ,recapitulation4--,relations of time and relations of space hold between sense-objects of perception4 ,these sense-objects are distinguished as separate objects by the recognition of either 7#a7 differences of sense-content1 or 7#b7 time-relations between them other than simultaneity1 or 7#c7 space-relations between them other than coincidence4 ,thus sense-objects arise from the recognition of contrast within the complete stream of sense-presentation1 namely1 from the recognition of the objects as related terms1 by relations which contrast them4 ,differences of sense-content are infinitely complex in their variety4 ,their analysis under the heading of general ideas is the unending task of physical science4 ,time-relations and space-relations are comparatively simple1 and the general ideas according to which their analysis should proceed are obvious4 ,this simplicity of time and space is perhaps the reason why thought chooses them as the permanent ground for objectival distinction1 throwing the various sense-objects thus obtainable into one heap1 as a first crude thought-object of perception1 and thence1 as described above1 obtaining a thought-object of perception4 ,thus a thought-object of perception conceived as in the present of a short duration is a first crude thought-object of perception either actual or hypothetical4 ,such a thought-object of perception1 confined within a short duration1 takes on the space-relations of its component sense-objects within that same duration4 ,accordingly thought-objects of perception1 conceived in their whole extents1 have to each other the time-relationships of their complete existences1 and within any small duration have to each other the space-relationships of their component sense-objects which lie within that duration4 ,relations bind together3 thus thought-objects of perception are connected in time and in space4 ,the genesis of the objectival analysis of sense-presentation is the recognition of sense-objects as distinct terms in time-relations and space-relations3 thus thought-objects of perception are separated by time and by space4 ,whole and ,part4--,a sense-object is part of the complete stream of presentation4 ,this concept of being a part is merely the statement of the relation of the sense-object to the complete sense-presentation for that consciousness4 ,also a sense-object can be part of another sense-object4 ,it can be a part in two ways1 namely1 a part in time and a part in space4 ,it seems probable that both these concepts of time-part and space-part are fundamental2 that is1 are concepts expressing relations which are directly presented to us1 and are not concepts about concepts4 ,in that case no further definition of the actual presentation is possible4 ,it may even then be possible to define an adequate criterion of the occurrence of such a presentation4 ,for example1 adopting for the moment a realist metaphysic as to the existence of the physical world of molecules and electrons1 the vision of a chair as occurring for some definite person at some definite time is essentially indefinable4 ,it is his vision1 though each of us guesses that it must be uncommonly like our vision under analogous circumstances4 ,but the existence of the definable molecules and waves of light in certain definable relations to his bodily organs of sense1 his body also being in a certain definable state1 forms an adequate criterion of the occurrence of the vision1 a criterion which is accepted in ,courts of ,law and for physical science is tacitly substituted for the vision4 ,the connection between the relations whole and part and all and some is intimate4 ,it can be explained thus so far as concerns directly presented sense-objects4 ,call two sense-objects separated if there is no third sense-object which is a part of both of them4 ,then an object ,a is composed of the two objects ,b and ,c1 if 7#a7 ,b and ,c are both parts of ,a1 7#b7 ,b and ,c are separated1 and 7#c7 there is no part of ,a which is separated both from ,b and from ,c4 ,in such a case the class which is composed of the two objects ,b and ,c is often substituted in thought for the sense-object ,a4 ,but this process presupposes the fundamental relation whole and part4 ,conversely the objects ,b and ,c may be actual sense-objects1 but the sense-object ,a which corresponds to the class may remain hypothetical4 ,for example1 the round world on which we live remains a conception corresponding to no single sense-object at any time presented in any human being's consciousness4 ,it is possible1 however1 that some mode of conceiving the whole-and-part relation between extended objects as the all-and-some relation of logical classes can be found4 ,but in this case the extended objects as here conceived cannot be the true sense-objects which are present to consciousness4 ,for as here conceived a part of a sense-object is another sense-object of the same type2 and therefore one sense-object cannot be a class of other sense-objects1 just as a tea-spoon cannot be a class of other tea-spoons4 ,the ordinary way in thought by which whole-and-part is reduced to all-and-some is by the device of points1 namely1 the part of an object occupies some of the points occupied by the whole object4 ,if any one holds that in his consciousness the sense-presentation is a presentation of point-objects1 and that an extended object is merely a class of such point-objects collected together in thought1 then this ordinary method is completely satisfactory4 ,we shall proceed on the assumption that this conception of directly perceived point-objects has no relation to the facts4 ,in the preceding address on ,the ,organisation of ,thought1 another mode is suggested4 ,but this method would apply only to the thought-object of perception1 and has no reference to the primary sense-objects here considered4 ,accordingly it must reckon as a subordinate device for a later stage of thought4 ,thus the point-object in time and the point-object in space1 and the double point-object both in time and space1 must be conceived as intellectual constructions4 ,the fundamental fact is the sense-object1 extended both in time and space1 with the fundamental relation of whole-to-part to other such objects1 and subject to the law of convergence to simplicity as we proceed in thought through a series of successively contained parts4 ,the relation whole-to-part is a temporal or spatial relation1 and is therefore primarily a relation holding between sense-objects of perception1 and it is only derivatively ascribed to the thought-objects of perception of which they are components4 ,more generally1 space and time relations hold primarily between sense-objects of perception and derivatively between thought-objects of perception4 ,definition of ,points4--,the genesis of points of time and of space can now be studied4 ,we must distinguish 7#a7 sense-time and sense-space1 and 7#b7 thought-time of perception and thought-space of perception4 ,sense-time and sense-space are the actually observed time-relations and space-relations between sense-objects4 ,sense-time and sense-space have no points except1 perhaps1 a few sparse instances1 sufficient to suggest the logical idea2 also1 sense-time and sense-space are discontinuous and fragmentary4 ,thought-time of perception and thought-space of perception are the time and space relations which hold between thought-objects of perception4 ,thought-time of perception and thought-space of perception are each continuous4 ,by continuous is here meant that all thought-objects of perception have to each other a time 7or space7 relation4 ,the origin of points is the effort to take full advantage of the principle of convergence to simplicity4 ,in so far as this principle does not apply1 a point is merely a cumbrous way of directing attention to a set of relations between a certain set of thought-objects of perception1 which set of relations1 though actual so far as a thought-object is actual1 is 7under this supposition7 of no particular importance4 ,thus the proved importance in physical science of the concepts of points in time and points in space is a tribute to the wide applicability of this principle of convergence4 ,euclid defines a point as without parts and without magnitude4 ,in modern language a point is often described as an ideal limit by indefinitely continuing the process of diminishing a volume 7or area74 ,points as thus conceived are often called convenient fictions4 ,this language is ambiguous4 ,what is meant by a fiction8 ,if it means a conception which does not correspond to any fact1 there is some difficulty in understanding how it can be of any use in physical science4 ,for example1 the fiction of a red man in a green coat inhabiting the moon can never be of the slightest scientific service1 simply because--as we may presume--it corresponds to no fact4 ,by calling the concept of points a convenient fiction1 it must be meant that the concept does correspond to some important facts4 ,it is1 then1 requisite1 in the place of such vague allusiveness1 to explain exactly what are the facts to which the concept corresponds4 ,we are not much helped by explaining that a point is an ideal limit4 ,what is a limit8 ,the idea of a limit has a precise meaning in the theory of series1 and in the theory of the values of functions2 but neither of these meanings apply here4 ,it may be observed that1 before the ordinary mathematical meanings of limit had received a precise explanation1 the idea of a point as a limit might be considered as one among other examples of an idea only to be apprehended by direct intuition4 ,this view is not now open to us4 ,thus1 again1 we are confronted with the question3 ,what are the precise properties meant when a point is described as an ideal limit8 ,the discussion which now follows is an attempt to express the concept of a point in terms of thought-objects of perception related together by the whole-and-part relation1 considered either as a time-relation or as a space-relation4 ,if it is so preferred1 it may be considered that the discussion is directed towards a precise elucidation of the term ideal limit as often used in this connection4 ,the subsequent explanations can be made easier to follow by a small piece of symbolism3 ,let a,eb mean that b is part of a4 ,we need not decide whether we are talking of time-parts or space-parts1 but whichever choice is supposed to be made must be conceived as adhered to throughout any connected discussion4 ,the symbol ,e may be considered as the initial letter of encloses1 so we read a,eb as a encloses b4 ,again the field of ,e is the set of things which either enclose or are enclosed1 i4 e4 everything a1 which is such that x can be found so that either a,ex or x,ea4 ,a member of the field of ,e is called an enclosure-object4 ,now1 we assume that this relation of whole-to-part1 which in the future we will call enclosure1 always satisfies the conditions in that the relation ,e is 7#a7 transitive1 7#b7 asymmetrical1 and 7#c7 with its domain including its converse domain4 ,these four conditions deserve some slight consideration2 only the first two of them embody hypotheses which enter vitally into the reasoning4 ,condition 7#a7 may be stated as the condition that a,eb and b,ec always implies a,ec4 ,the fact that an entity b can be found such that a,eb and b,ec may be conceived as a relation between a and c4 ,it is natural to write ,e#b for this relation4 ,thus the condition is now written3 ,if a,e#b;c1 then a,ec4 ,this can be still otherwise expressed by saying that the relation ,e#b implies1 whenever it holds1 that the relation ,e also holds4 ,condition 7#b7 is partly a mere question of trivial definition1 and partly a substantial assumption4 ,the asymmetrical relation 7,e7 is such that a,eb and b,ea can never hold simultaneously4 ,this property splits up into two parts3 7#a7 that no instance of a,eb and b,ea and a diverse from b1 can occur1 and 7#b7 that a,ea cannot occur4 ,the first part is a substantial assumption1 the second part 7so far as we are concerned7 reduces to the trivial convention that we shall not consider an object as part of itself1 but will confine attention to proper parts4 ,condition 7#c7 means that a,eb always implies that c can be found such that b,ec4 ,this condition1 taken in conjunction with the fact that we are only considering proper parts1 is the assertion of the principle of the indefinite divisibility of extended objects1 both in space and in time4 ,an indivisible part will lack duration in time1 and extension in space1 and is thus an entity of essentially a different character to a divisible part4 ,if we admit such indivisibles as the only true sense-objects1 our subsequent procedure is an unnecessary elaboration4 ,it will be found that a fourth condition is necessary owing to logical difficulties connected with the theory of an infinite number of choices4 ,it will not be necessary for us to enter further on this question1 which involves difficult considerations of abstract logic4 ,the outcome is1 that apart from hypothesis we cannot prove the existence of the sets1 each containing an infinite number of objects1 which are here called points1 as will be explained immediately4 ,now consider a set of enclosure objects which is such that 7#a7 of any two of its members one encloses the other1 and 7#b7 there is no member which is enclosed by all the others1 and 7#c7 there is no enclosure-object1 not a member of the set which is enclosed by every member of the set4 ,call such a set a convergent set of enclosure-objects4 ,as we pass along the series from larger to smaller members1 evidently we converge towards an ideal simplicity to any degree of approximation to which we like to proceed1 and the series as a whole embodies the complete ideal along that route of approximation4 ,in fact1 to repeat1 the series is a route of approximation4 ,we have now to inquire if the principle of convergence to simplicity may be expected to yield the same type of simplicity for every such convergent route4 ,the answer is1 as we might expect1 namely1 that this depends upon the nature of the properties which are to be simplified4 ,for example1 consider the application to time4 ,now1 time is one-dimensional2 so when this property of one-dimensionality has been expressed by the proper conditions1 not here stated1 a convergent set of enclosure-objects must1 considered as a route of approximation1 exhibit the properties of one unique instant of time1 as ordinarily conceived by the euclidean definition4 ,accordingly1 whatever simplicity is to be achieved by the application to time of the principle of convergence to simplicity must be exhibited among the properties of any such route of approximation4 ,for space1 different considerations arise4 ,owing to its multiple dimensions1 we can show that different convergent sets of enclosure-objects1 indicating different routes of approximation1 may exhibit convergence to different types of simplicity1 some more complex than others4 ,for example1 consider a rectangular box of height h ft41 breadth b ft41 and thickness c ft4 ,now1 keep h and b constant1 and let the central plane 7height h1 breadth b7 perpendicular to the thickness be fixed1 then make c diminish indefinitely4 ,we thus obtain a convergent series of an indefinitely large number of boxes1 and there is no smallest box4 ,thus this convergent series exhibits the route of approximation towards the type of simplicity expressed as being a plane area of height h1 breadth b1 and no thickness4 ,again1 by keeping the central line of height h fixed1 and by making b and c diminish indefinitely1 the series converges to the segment of a straight line of length h4 ,finally1 by keeping only the central point fixed1 and by making h1 b1 and c diminish indefinitely1 the series converges to a point4 ,furthermore1 we have introduced as yet no concept which would prevent an enclosure-object being formed of detached fragments in space4 ,thus we can easily imagine a convergent set which converges to a number of points in space4 ,for example1 each object of the set might be formed of two not overlapping spheres of radius r1 with centres ,a and ,b4 ,then by diminishing r indefinitely1 and keeping ,a and ,b fixed1 we have convergence to the pair of points ,a and ,b4 ,it remains now to consider how those convergent sets which converge to a single point can be discriminated from all the other types of such sets1 merely by utilising concepts founded on the relation of enclosure4 ,let us name convergent sets by ,greek letters2 by proceeding forward along any such set let us understand the process of continually passing from the larger to the smaller enclosure-objects which form the set4 ,the convergent set will be said to cover the convergent set 1 if every member of encloses some members of 4 ,we notice that if an enclosure-object x encloses any member 7y7 of 1 then every member of the tail-end of 1 found by proceeding forward along from y1 must be enclosed by x4 ,thus if covers 1 every member of encloses every member of the tail-end of 1 starting from the largest member of which is enclosed by that member of 4 ,it is possible for each of two convergent sets to cover the other4 ,for example1 let one set 77 be a set of concentric spheres converging to their centre ,a1 and the other set 77 be a set of concentric cubes1 similarly situated1 converging to the same centre ,a4 ,then and will each cover the other4 ,let two convergent sets which are such that each covers the other be called equal4 ,then it is a sufficient condition to secure that a convergent set possesses the point type of convergence1 if every convergent set covered by it is also equal to it1 namely1 is a convergent set with the punctual type of convergence1 if covers always implies that covers 4 ,it can easily be seen by simple examples that the other types of convergence to surfaces or lines or sets of points cannot possess this property4 ,consider1 for example1 the three convergent sets of boxes in the preceding illustration1 which converge respectively to a central plane1 a central line in the central plane1 and the central point in the central line4 ,the first set covers the second and third sets1 and the second set covers the third set1 but no two of the sets are equal4 ,it is a more difficult question to determine whether the condition here indicated as sufficient to secure the punctual type of convergence is also necessary4 ,the question turns on how far thought-objects of perception possess exact boundaries prior to the elaboration of exact mathematical concepts of space4 ,if they are to be conceived as possessing such exact boundaries1 then convergent sets converging to points on such boundaries must be allowed for4 ,the procedure necessary for the specification of the complete punctual condition becomes then very elaborate1#c and will not be considered here4 ,but such exact determination as is involved in the conception of an exact spatial boundary does not seem to belong to the true thought-object of perception4 ,the ascription of an exact boundary really belongs to the transition stage of thought as it passes from the thought-object of perception to the thought-object of science4 ,the transition from the sense-object immediately presented to the thought-object of perception is historically made in a wavering indeterminate line of thought4 ,the definite stages here marked out simply serve to prove that a logically explicable transition is possible4 ,we accordingly assume that the condition laid down above to secure the punctual convergence of a convergent set of enclosure-objects is not only sufficient1 but necessary4 ,it can be proved that1 if two convergent sets of enclosure-objects are both equal to a third convergent set1 they are equal to each other4 ,consider now any punctual convergent set 774 ,we want to define the point to which is a route of approximation in a way which is neutral between and all the convergent sets which are equal to 4 ,each of these sets is a route of approximation to the same point as 4 ,this definition is secured if we define the point as the class formed by all the enclosure-objects which belong either to or to any convergent set which is equal to 4 ,let ,p be this class of enclosure-objects4 ,then any convergent set 77 which consists of enclosure-objects entirely selected from members of the class ,p must be a route of approximation to the same point as does the original punctual set 2 namely1 provided that we choose a small enough enclosure-object in 1 we can always find a member of which encloses it2 and provided that we choose a small enough enclosure-object in 1 we can always find a member of which encloses it4 ,thus ,p only includes convergent sets of the punctual type1 and the route of approximation indicated by any two convergent sets selected from ,p converges to identical results4 ,the ,uses of ,points4--,the sole use of points is to facilitate the employment of the principle of ,convergence to ,simplicity4 ,by this principle some simple relations in appropriate circumstances become true1 when objects are considered which are sufficiently restricted in time or in space4 ,the introduction of points enables this principle to be carried through to its ideal limit4 ,for example1 suppose g 7a1 b1 c7 represents some statement concerning three enclosure-objects1 a1 b1 c1 which may be true if the objects are sufficiently restricted in extent4 ,let ,a1 ,b1 ,c be three given points1 then we define g 7,a1 ,b1 ,c7 to mean that whatever three enclosure-objects a1 b1 c are chosen1 such that a is a member of ,a1 b of ,b1 and c of ,c1 it is always possible to find three other members of ,a1 ,b1 ,c1 namely1 x a member of ,a1 y of ,b1 and z of ,c1 such that a,ex1 b,ey1 c,ez1 and g 7x1 y1 z74 ,so by going far enough down in the tail-ends of ,a1 ,b1 ,c we can always secure three objects x1 y1 z for which g 7x1 y1 z7 is true4 ,for example1 let g 7,a1 ,b1 ,c7 mean ,a1 ,b1 ,c are three points in a linear row4 ,this must be construed to mean that whatever three objects a1 b1 c we choose1 members of ,a1 ,b1 ,c respectively1 we can always find three objects x1 y1 z1 also members of ,a1 ,b1 ,c respectively1 and such that a encloses x1 b encloses y1 c encloses z1 and also such that x1 y1 z are in a linear row4 ,sometimes a double convergence is necessary1 namely1 a convergence of conditions as well as a convergence of objects4 ,for example1 consider the statement1 the points ,a and ,b are two feet apart4 ,now1 the exact statement two feet apart does not apply to objects4 ,for objects x and y we must substitute the statement1 the distance between x and y lies between the limits 7#b e7 feet4 ,here e is some number1 less than two1 which we have chosen for this statement4 ,then the points ,a and ,b are two feet apart2 if1 however we choose the number e1 whatever enclosure-objects a and b1 members of ,a and ,b respectively1 we consider1 we can always find enclosure-objects x and y1 members of ,a and ,b respectively1 such that a encloses x and b encloses y1 and also such that the distance between x and y lies between the limits 7#b e7 feet4 ,it is evident1 since e can be chosen as small as we please1 that this statement exactly expresses the condition that ,a and ,b are two feet apart4 ,straight ,lines and ,planes4--,but the problem of the intellectual construction of straight lines and planes is not yet sufficiently analysed4 ,we have interpreted the meaning of the statement that three or more points are collinear1 and can similarly see how to interpret the meaning of the statement that four or more points are coplanar1 in either case deriving the exact geometrical statements from vaguer statements respecting extended objects4 ,this procedure only contemplates groups of finite numbers of points4 ,but straight lines and planes are conceived as containing infinite numbers of points4 ,this completion of lines and planes is obtained by a renewed application of the principle of aggregation1 just as a set of first crude thought-objects of perception are aggregated into one complete thought-object of perception4 ,in this way repeated judgments of the collinearity of sets of points are finally1 when certain conditions of interlacing are fulfilled1 aggregated in the single judgment of all the points of the groups as forming one whole collinear group4 ,similarly for judgments of coplanarity4 ,this process of logical aggregation can be exhibited in its exact logical analysis4 ,but it is unnecessary here to proceed to such details4 ,thus we conceive our points as sorted into planes and straight lines1 concerning which the various axioms of geometry hold4 ,these axioms1 in so far as they essentially require the conception of points1 are capable of being exhibited as the outcome of vaguer1 less exact judgments respecting the relations of extended objects4 ,empty ,space4--,it must be observed that the points1 hitherto defined1 necessarily involve thought-objects of perception1 and lie within the space-extension occupied by such objects4 ,it is true that such objects are largely hypothetical1 and that we can bring into our hypotheses sufficient objects to complete our lines and planes4 ,but every such hypothesis weakens the connection between our scientific concept of nature and the actual observed facts which are involved in the actual sense-presentations4 ,occam's razor1 ,entia non multiplicanda prter necessitatem1 is not an arbitrary rule based on mere logical elegancy4 ,nor is its application purely confined to metaphysical speculation4 ,i am ignorant of the precise reason for its metaphysical validity1 but its scientific validity is obvious1 namely1 every use of hypothetical entities diminishes the claim of scientific reasoning to be the necessary outcome of a harmony between thought and sense-presentation4 ,as hypothesis increases1 necessity diminishes4 ,commonsense thought also supports this refusal to conceive of all space as essentially depending on hypothetical objects which fill it4 ,we think of material objects as filling space1 but we ask whether any objects exist between the ,earth and the ,sun1 between the stars1 or beyond the stars4 ,for us1 space is there2 the only question is whether or not it be full4 ,but this form of question presupposes the meaning of empty space1 namely1 of space not containing hypothetical objects4 ,this brings up a wider use of the concept of points1 necessitating a wider definition4 ,hitherto we have conceived points as indicating relations of enclosure between objects4 ,we thus arrive at what now we will term material points4 ,but the idea of points can now be transformed so as to indicate the possibilities of external relations not those of enclosure4 ,this is effected by an enlargement of the concept of ideal points1 already known to geometers4 ,define material lines to be complete collinear classes of collinear points4 ,consider now the set of material lines which contain a certain material point4 ,call such a set of lines an ideal point4 ,this set of lines indicates a possibility of position1 which is in fact occupied by that material point common to all the material lines4 ,so this ideal point is an occupied ideal point4 ,now consider a set of three material lines1 such that any two are coplanar1 but not the whole three1 and further consider the complete set of material lines such that each is coplanar with each of the three material lines first chosen4 ,the axioms which hold for the material lines will enable us to prove that any two lines of this set are coplanar4 ,then the whole set of lines1 including the three original lines1 forms an ideal point1 according to the definition in its full generality4 ,such an ideal point may be occupied4 ,in that case there is a material point common to all the lines of the set1 but it may be unoccupied4 ,then the ideal point merely indicates a possibility of spatial relations which has not been realised4 ,it is the point of empty space4 ,thus the ideal points1 which may or may not be occupied1 are the points of geometry viewed as an applied science4 ,these points are distributed into straight lines and planes4 ,but any further discussion of this question will lead us into the technical subject of the axioms of geometry and their immediate consequences4 ,enough has been said to show how geometry arises according to the relational theory of space4 ,space as thus conceived is the thought-space of the material world4 ,,iv4 ,fields of ,force ,the thought-objects of science are conceived as directly related to this thought-space4 ,their spatial relations are among those indicated by the points of the thought-space4 ,their emergence in science has been merely a further development of processes already inherent in commonsense thought4 ,relations within the complete sense-presentation were represented in thought by the concept of thought-objects of perception4 ,all sense-presentation could not be represented in this way2 also the change and disappearance of thought-objects occasioned confusion of thought4 ,a reduction to order of this confusion was attempted by the concepts of permanent matter with primary and secondary qualities4 ,finally1 this has issued in the secondary qualities being traced as perception of events generated by the objects1 but--as perceived--entirely disconnected with them4 ,also the thought-objects of perception have been replaced by molecules and electrons and ether-waves1 until at length it is never the thought-object of science which is perceived1 but complicated series of events in which they are implicated4 ,if science be right1 nobody ever perceived a thing1 but only an event4 ,the result is1 that the older language of philosophy which still survives in many quarters is now thoroughly confusing when brought into connection with the modern concepts of science4 ,philosophy--that is1 the older philosophy--conceives the thing as directly perceived4 ,according to scientific thought1 the ultimate thing is never perceived1 perception essentially issuing from a series of events4 ,it is impossible to reconcile the two points of view4 ,the advantage of the modern scientific concept is that it is enabled to explain the fluid vague outlines of sense-presentation4 ,the thought-object of perception is now conceived as a fairly stable state of motion of a huge group of molecules1 constantly changing1 but preserving a certain identity of characteristics4 ,also stray sense-objects1 not immediately given as part of a thought-object of perception1 are now explicable3 the dancing light-reflection1 the vaguely heard sound1 the smell4 ,in fact1 the perceived events of the scientific world have the same general definition and lack of definition1 and the same general stability and lack of stability1 as the sense-objects of the complete sense-presentation or as the thought-objects of perception4 ,the thought-objects of science1 namely1 molecules1 atoms1 and electrons1 have gained in permanence4 ,the events are reduced to changes in space-configuration4 ,the laws determining these changes are the ultimate laws of nature4 ,the laws of change in the physical universe proceed on the assumption that the preceding states of the universe determine the character of the change4 ,thus1 to know the configurations and events of the universe up to and including any instant would involve sufficient data from which to determine the succession of events throughout all time4 ,but in tracing the antecedents of events1 commonsense thought1 dealing with the world of thought-objects of perception1 habitually assumes that the greater number of antecedent events can be neglected as irrelevant4 ,consideration of causes is restricted to a few events during a short preceding interval4 ,finally1 in scientific thought it has been assumed that the events in an arbitrarily small preceding duration are sufficient4 ,thus physical quantities and their successive differential co-efficients up to any order at the instant1 but with their limiting values just before that instant1 are on this theory sufficient to determine the state of the universe at all times after the instant4 ,more particular laws are assumed4 ,but the search for them is guided by this general principle4 ,also it is assumed that the greater number of events in the physical universe are irrelevant to the production of any particular effect1 which is assumed to issue from relatively few antecedents4 ,these assumptions have grown out of the experience of mankind4 ,the first lesson of life is to concentrate attention on few factors of sense-presentations1 and on still fewer of the universe of thought-objects of perception4 ,the principle by which--consciously or unconsciously--thought has been guided is that in searching for particular causes1 remoteness in time and remoteness in space are evidences of comparative disconnection of influence4 ,the extreme form of this principle is the denial of any action at a distance either in time or space4 ,the difficulty in accepting this principle in its crude form is1 that since there are no contiguous points1 only coincident bodies can act on each other4 ,i can see no answer to this difficulty--namely1 either bodies have the same location and are thus coincident1 or they have different locations and are thus at a distance and do not act on each other4 ,this difficulty is not evaded by the hypothesis of an ether1 continuously distributed4 ,for two reasons3 in the first place1 the continuity of the ether does not avoid the dilemma2 and secondly1 the difficulty applies to time as well as to space1 and the dilemma would prove that causation producing change is impossible1 namely1 no changed condition could be the result of antecedent circumstances4 ,on the other hand1 a direct interaction between two bodies separated in space undoubtedly offends the conception of distance as implying physical disconnection as well as spatial relation4 ,there is no logical difficulty in the assumption of action at a distance as in the case of its denial1 but it is contradictory to persistent assumptions of that apparatus of commonsense thought which it is the main business of science to harmonise with sense-presentation1 employing only the minimum of modification4 ,modern science is really unconcerned with this debate4 ,its 7unacknowledged7 conceptions are really quite different1 though the verbal explanations retain the form of a previous epoch4 ,the point of the change in conception is that the old thought-object of science was conceived as possessing a simplicity not belonging to the material universe as a whole4 ,it was secluded within a finite region of space1 and changes in its circumstances could only arise from forces which formed no essential part of its nature4 ,an ether was called into existence to explain the active relations between these passive thought-objects4 ,the whole conception suffers from the logical difficulties noted above4 ,also no clear conception can be formed of the sense in which the ether is explanatory4 ,it is to possess a type of activity denied to the original thought-object1 namely1 it carries potential energy1 whereas the atom possessed only kinetic energy1 the so-called potential energy of an atom belonging really to the surrounding ether4 ,the truth is1 that ether is really excepted from the axiom no action at a distance1 and the axiom thereby is robbed of all its force4 ,the modern thought-object of science--not yet explicitly acknowledged--has the complexity of the whole material universe4 ,in physics1 as elsewhere1 the hopeless endeavour to derive complexity from simplicity has been tacitly abandoned4 ,what is aimed at is not simplicity1 but persistence and regularity4 ,in a sense regularity is a sort of simplicity4 ,but it is the simplicity of stable mutual relations1 and not the simplicity of absence of types of internal structure or of type of relation4 ,this thought-object fills all space4 ,it is a field2 that is to say1 it is a certain distribution of scalar and vector quantities throughout space1 these quantities having each its value for each point of space at each point of time1 being continuously distributed throughout space and throughout time1 possibly with some exceptional discontinuities4 ,the various types of quantity which form the field have fixed relations to each other at each point of time and space4 ,these relations are the ultimate laws of nature4 ,for example1 consider an electron4 ,there is a scalar distribution of electricity1 which is what is ordinarily called the electron4 ,this scalar distribution has a volume-density at the time t at any point 7x1 y1 z74 ,thus is a function of 7x1 y1 z1 t71 which is zero except within a restricted region4 ,furthermore1 at any time t1 as an essential adjunct1 there is a continuous space distribution at each point of the two vectors 7,x1 ,y1 ,z71 which is the electric force1 and 71 1 71 which is the magnetic force4 ,lastly1 individuality is ascribed to the scalar electric distribution1 so that in addition to its conservation of quantity--involved in the assumed laws--it is also possible to assign the velocities with which the various individual parts of the distribution are moving4 ,let 7u1 v1 w7 be this velocity at 7x1 y1 z1 t74 ,this whole scheme of scalar and vector quantities1 namely1 1 7,x1 ,y1 ,z71 71 1 71 7u1 v1 w7 is interconnected by the electromagnetic laws4 ,it follows from these laws that the electron1 in the sense of the scalar distribution 1 is to be conceived as at each instant propagating from itself an emanation which travels outwards with the velocity of light in vacuo1 and from which 7,x1 ,y1 ,z7 and 71 1 7 can be calculated1 so far as they are due to that electron4 ,thus the field1 at any time1 due to the electron as a whole depends on the previous history of the electron1 the nearer to the electron the more recent being the relevant history4 ,the whole scheme of such a field is one single thought-object of science3 the electron and its emanations form one essential whole1 namely one thought-object of science1 essentially complex and essentially filling all space4 ,the electron proper1 namely1 the scalar distribution 1 is the focus of the whole1 the essential focal property being that the field at any instant is completely determined by the previous history of the focus and of its space relations through all previous time4 ,but the field and the focus are not independent concepts1 they are essentially correlated in one organised unity1 namely1 they are essentially correlated terms in the field of one relation in virtue of which the entities enter into our thoughts4 ,the fields of a group of electrons are superposed according to the linear law for aggregation1 namely1 pure addition for analogous scalar quantities and the parallelogram law for analogous vectors4 ,the changes in motion of each electron depend entirely on the resultant field in the region it occupies4 ,thus a field can be viewed as a possibility of action1 but a possibility which represents an actuality4 ,it is to be noted that the two alternative views of causation are here both included4 ,the complete field within any region of space depends on the past histories of all the electrons1 histories extending backwards in proportion to their distances4 ,also this dependence can be conceived as a transmission4 ,but viewing the cause which effects changes on the electron within that region1 it is solely that field within the region1 which field is coincident with that electron both in time and in space4 ,this process of conceiving the actuality underlying a possibility is the uniform process by which regularity and permanence is introduced into scientific thought1 namely1 we proceed from the actuality of the fact to the actuality of possibility4 ,in conformity with this principle1 propositions are the outgrowth from actual thought-expressions1 thought-objects of perceptions from crude sense-objects1 hypothetical thought-objects of perception from actual thought-objects of perception1 material points from hypothetical infinite suites of hypothetical thought-objects of perception1 ideal points from material points1 thought-objects of science from thought-objects of perception1 fields of electrons from actual mutual reactions of actual electrons4 ,the process is a research for permanence1 uniformity1 and simplicity of logical relation4 ,but it does not issue in simplicity of internal structure4 ,each ultimate thought-object of science retains every quality attributed to the whole scientific universe1 but retains them in a form characterised by permanence and uniformity4 ,v4 ,conclusion ,we commenced by excluding judgments of worth and ontological judgments4 ,we conclude by recalling them4 ,judgments of worth are no part of the texture of physical science1 but they are part of the motive of its production4 ,mankind have raised the edifice of science1 because they have judged it worth while4 ,in other words1 the motives involve innumerable judgments of value4 ,again1 there has been conscious selection of the parts of the scientific field to be cultivated1 and this conscious selection involves judgments of value4 ,these values may be sthetic1 or moral1 or utilitarian1 namely1 judgments as to the beauty of the structure1 or as to the duty of exploring the truth1 or as to utility in the satisfaction of physical wants4 ,but whatever the motive1 without judgments of value there would have been no science4 ,again1 ontological judgments were not excluded by reason of any lack of interest4 ,they are in fact presupposed in every act of life3 in our affections1 in our self-restraints1 and in our constructive efforts4 ,they are presupposed in moral judgments4 ,the difficulty about them is the absence of agreement as to the method of harmonising the crude judgments of commonsense4 ,science does not diminish the need of a metaphysic4 ,where this need is most insistent is in connection with what above has been termed the actuality underlying a possibility4 ,a few words of explanation may render the argument clearer1 although they involve a rash approach to metaphysical heights which it is not the purpose of this paper to explore4 ,the conception of subject and object in careless discussion covers two distinct relations4 ,there is the relation of the whole perceiving consciousness to part of its own content1 for example1 the relation of a perceiving consciousness to an object of redness apparent to it4 ,there is also the relation of a perceiving consciousness to an entity which does not exist in virtue of being part of the content of that consciousness4 ,such a relation1 so far as known to the perceiving consciousness1 must be an inferred relation1 the inference being derived from an analysis of the content of the perceiving consciousness4 ,the bases for such inferences must be elements in consciousness directly known as transcending their immediate presentation in consciousness4 ,such elements are universal logical truths1 moral and sthetic truths1 and truths embodied in hypothetical propositions4 ,these are the immediate objects of perception which are other than the mere affections of the perceiving subject4 ,they have the property of being parts of the immediate presentations for individual subjects and yet more than such parts4 ,all other existence is inferred existence4 ,in this chapter we are more directly concerned with truths embodied in hypothetical propositions4 ,such truths must not be confused with any doubtfulness which attaches to our judgments of the future course of natural phenomena4 ,a hypothetical proposition1 like a categorical judgment1 may or may not be doubtful4 ,also like a categorial judgment1 it expresses a fact4 ,this fact is twofold3 as a presentation in consciousness1 it is just this hypothetical judgment2 as expressing a categorical fact1 it states a relation which lies beyond consciousness1 holding between entities thereby inferred4 ,but this metaphysical analysis1 short though it be1 is probably wrong1 and at the best will only command very partial assent4 ,certainly2 and this admission brings out the very point which ,i wished to make4 ,physical science is based on elements of thought1 such as judgments registering actual perceptions1 and judgments registering hypothetical perceptions which under certain circumstances would be realised4 ,these elements form the agreed content of the apparatus of commonsense thought4 ,they require metaphysical analysis2 but they are among the data from which metaphysics starts4 ,a metaphysic which rejects them has failed1 in the same way as physical science has failed when it is unable to harmonise them into its theory4 ,science only renders the metaphysical need more urgent4 ,in itself it contributes little directly to the solution of the metaphysical problem4 ,but it does contribute something1 namely1 the exposition of the fact that our experience of sensible apparent things is capable of being analysed into a scientific theory1 a theory not indeed complete1 but giving every promise of indefinite expansion4 ,this achievement emphasises the intimate relation between our logical thought and the facts of sensible apprehension4 ,also the special form of scientific theory is bound to have some influence4 ,in the past false science has been the parent of bad metaphysics4 ,after all1 science embodies a rigorous scrutiny of one part of the whole evidence from which metaphysicians deduce their conclusions4 ,,footnotes3 ,footnote #c3 ,cf4 ,rvue de ,mtaphysique et de ,morale1 ,may #aiaf1 where this question is dealt with by the author at the end of an article1 ,la thorie relationniste de l'espace4 ,,chapter ,,viii ,,space1 ,,time1 ,,and ,,relativity 7,paper read to ,section ,a at the ,manchester ,meeting of the ,british ,association1 #aiae1 and later before the ,aristotelian ,society7 ,,fundamental ,problems concerning space and time have been considered from the standpoints created by many different sciences4 ,the object of this paper is the humble one of bringing some of these standpoints into relation with each other4 ,this necessitates a very cursory treatment of each point of view4 ,mathematical physicists have evolved their theory of relativity to explain the negative results of the ,morley-,michelson experiment and of the ,trouton experiment4 ,experimental psychologists have considered the evolution of spatial ideas from the crude sense-data of experience4 ,metaphysicians have considered the majestic uniformity of space and time1 without beginning and without end1 without boundaries1 and without exception in the truths concerning them2 all these qualities the more arresting to our attention from the confused accidental nature of the empirical universe which is conditioned by them4 ,mathematicians have studied the axioms of geometry1 and can now deduce all that is believed to be universally true of space and of time by the strictest logic from a limited number of assumptions4 ,these various lines of thought have been evolved with surprisingly little interconnection4 ,perhaps it is as well4 ,the results of science are never quite true4 ,by a healthy independence of thought perhaps we sometimes avoid adding other people's errors to our own4 ,but there can be no doubt that the normal method of cross-fertilising thought is by considering the same1 or allied problems to our own1 in the form which they assume in other sciences4 ,here ,i do not propose to enter into a systematic study of these various chapters of science4 ,i have neither the knowledge nor the time4 ,first1 let us take the ultimate basis of any theory of relativity4 ,all space measurement is from stuff in space to stuff in space4 ,the geometrical entities of empty space never appear4 ,the only geometrical properties of which we have any direct knowledge are properties of those shifting1 changeable appearances which we call things in space4 ,it is the sun which is distant1 and the ball which is round1 and the lamp-posts which are in linear order4 ,wherever mankind may have got its idea of an infinite unchangeable space from1 it is safe to say that it is not an immediate deliverance of direct observation4 ,there are two antagonistic philosophical ways of recognising this conclusion4 ,one is to affirm that space and time are conditions for sensible experience1 that without projection into space and time sensible experience would not exist4 ,thus1 although it may be true to say that our knowledge of space and time is given in experience1 it is not true to say that it is deduced from experience in the same sense that the ,law of ,gravitation is so deduced4 ,it is not deduced1 because in the act of experiencing we are necessarily made aware of space as an infinite given whole1 and of time as an unending uniform succession4 ,this philosophical position is expressed by saying that space and time are a priori forms of sensibility4 ,the opposed philosophical method of dealing with the question is to affirm that our concepts of time and space are deductions from experience1 in exactly the same way as the ,law of ,gravitation is such a deduction4 ,if we form exact concepts of points1 lines and surfaces1 and of successive instants of time1 and assume them to be related as expressed by the axioms of geometry and the axioms for time1 then we find that we have framed a concept which1 with all the exactness of which our observations are capable1 expresses the facts of experience4 ,these two philosophic positions are each designed to explain a certain difficulty4 ,the a priori theory explains the absolute universality ascribed to the laws of space and time1 a universality not ascribed to any deduction from experience4 ,the experiential theory explains the derivation of the space-time concepts without introducing any other factors beyond those which are admittedly present in framing the other concepts of physical science4 ,but we have not yet done with the distinctions which in any discussion of space or time must essentially be kept in mind4 ,put aside the above question as to how these space-time concepts are related to experience--,what are they when they are formed8 ,we may conceive of the points of space as self-subsistent entities which have the indefinable relation of being occupied by the ultimate stuff 7matter1 ,i will call it7 which is there4 ,thus1 to say that the sun is there 7wherever it is7 is to affirm the relation of occupation between the set of positive and negative electrons which we call the sun and a certain set of points1 the points having an existence essentially independent of the sun4 ,this is the absolute theory of space4 ,the absolute theory is not popular just now1 but it has very respectable authority on its side--,newton1 for one--so treat it tenderly4 ,the other theory is associated with ,leibniz4 ,our space concepts are concepts of relations between things in space4 ,thus there is no such entity as a self-subsistent point4 ,a point is merely the name for some peculiarity of the relations between the matter which is1 in common language1 said to be in space4 ,it follows from the relative theory that a point should be definable in terms of the relations between material things4 ,so far as ,i am aware1 this outcome of the theory has escaped the notice of mathematicians1 who have invariably assumed the point as the ultimate starting ground of their reasoning4 ,many years ago ,i explained some types of ways in which we might achieve such a definition1 and more recently have added some others4 ,similar explanations apply to time4 ,before the theories of space and time have been carried to a satisfactory conclusion on the relational basis1 a long and careful scrutiny of the definitions of points of space and instants of time will have to be undertaken1 and many ways of effecting these definitions will have to be tried and compared4 ,this is an unwritten chapter of mathematics1 in much the same state as was the theory of parallels in the eighteenth century4 ,in this connection ,i should like to draw attention to the analogy between time and space4 ,in analysing our experience we distinguish events1 and we also distinguish things whose changing relations form the events4 ,if ,i had time it would be interesting to consider more closely these concepts of events and of things4 ,it must suffice now to point out that things have certain relations to each other which we consider as relations between the space extensions of the things2 for example1 one space can contain the other1 or exclude it1 or overlap it4 ,a point in space is nothing else than a certain set of relations between spatial extensions4 ,analogously1 there are certain relations between events which we express by saying that they are relations between the temporal durations of these events1 that is1 between the temporal extensions of the events4 ,the durations of two events ,a and ,b may one precede the other1 or may partially overlap1 or may one contain the other1 giving in all six possibilities4 ,the properties of the extension of an event in time are largely analogous to the extension of an object in space4 ,spatial extensions are expressed by relations between objects1 temporal extensions by relations between events4 ,the point in time is a set of relations between temporal extensions4 ,it needs very little reflection to convince us that a point in time is no direct deliverance of experience4 ,we live in durations1 and not in points4 ,but what community1 beyond the mere name1 is there between extension in time and extension in space8 ,in view of the intimate connection between time and space revealed by the modern theory of relativity1 this question has taken on a new importance4 ,i have not thought out an answer to this question4 ,i suggest1 however1 that time and space embody those relations between objects on which depends our judgment of their externality to ourselves4 ,namely1 location in space and location in time both embody and perhaps necessitate a judgment of externality4 ,this suggestion is very vague1 and ,i must leave it in this crude form4 ,diverse ,euclidean ,measure ,systems ,turning now to the mathematical investigations on the axioms of geometry1 the outcome1 which is most important for us to remember1 is the great separation which it discloses between non-metrical projective geometry1 and metrical geometry4 ,non-metrical projective geometry is by far the more fundamental4 ,starting with the concepts of points1 straight lines1 and planes 7of which not all three need be taken as indefinable71 and with certain very simple non-metrical properties of these entities--such as1 for instance1 that two points uniquely determine a straight line--nearly the whole of geometry can be constructed4 ,even quantitative coordinates can be introduced1 to facilitate the reasoning4 ,but no mention of distance1 area1 or volume1 need have been introduced4 ,points will have an order on the line1 but order does not imply any settled distance4 ,when we now inquire what measurements of distance are possible1 we find that there are different systems of measurement all equally possible4 ,there are three main types of system3 any system of one type gives ,euclidean geometry1 any system of another type gives ,hyperbolic 7or ,lobatchewskian7 geometry1 any system of the third type gives ,elliptic geometry4 ,also different beings1 or the same being if he chooses1 may reckon in different systems of the same type1 or in systems of different types4 ,consider the example which will interest us later4 ,two beings1 ,a and ,b1 agree to use the same three intersecting lines as axes of x1 y1 z4 ,they both employ a system of measurement of the ,euclidean type1 and 7what is not necessarily the case7 agree as to the plane at infinity4 ,that is1 they agree as to the lines which are parallel4 ,then with the usual method of rectangular ,cartesian axes1 they agree that the coordinates of ,p are the lengths ,,on1 ,,nm1 ,,mp4 ,so far all is harmony4 ,a fixes on the segment ,,ou#a1 on ,ox1 as being the unit length1 and ,b on the segment ,,ov#a1 on ,ox4 ,a calls his coordinates 7x1 y1 z71 and ,b calls them 7,x1 ,y1 ,z74 ,then it is found since both systems are ,euclidean that1 whatever point ,p be taken1 ,x x1 ,y y1 ,z z4 4 ,they proceed to adjust their differences1 and first take the x-coordinates4 ,obviously they have taken different units of length along ,ox4 ,the length ,,ou#a1 which ,a calls one unit1 ,b calls units4 ,b changes his unit length to ,,ou#a1 from its original length ,,ov#a1 and obtains ,x x4 ,but now1 as he must use the same unit for all his measurements1 his other coordinates are altered in the same ratio4 ,thus we now have ,x x1 ,y y_/1 ,z z_/4 ,the fundamental divergence is now evident4 ,a and ,b agree as to their units along ,ox4 ,they settled that by taking along that axis a given segment ,,ou#a as having the unit length4 ,but they cannot agree as to what segment along ,oy is equal to ,,ou#a4 ,a says it is ,,ou#b1 and ,b that it is ,,ou#b4 ,similarly for lengths along ,,oz4 ,the result is that ,a's spheres x#b y#b z#b r#b1 are ,b's ellipsoids1 ,x#b #b,y#b_/b #b,z#b_/b r#b1 i4 e4 ,x#b_/b ,y#b_/b ,z#b_/b r#b_/b4 ,thus the measurement of angles by the two is hopelessly at variance4 ,if 1 there is one1 and only one1 set of common rectangular axes at ,o1 namely that from which they started4 ,if 1 but 1 then there are a singly infinite number of common rectangular axes found by rotating the axes round ,ox4 ,this is1 for us1 the interesting case4 ,the same phenomena are reproduced by transferring to any parallel axes4 ,the root of the difficulty is1 that ,a's measuring rod1 which for him is a rigid invariable body1 appears to ,b as changing in length when turned in different directions4 ,similarly all measuring rods1 satisfactory to ,a1 violate ,b's immediate judgment of invariability1 and change according to the same law4 ,there is no way out of the difficulty4 ,two rods and coincide whenever laid one on the other2 is held still1 and both men agree that it does not change4 ,but is turned round4 ,a says it is invariable1 ,b says it changes4 ,to test the matter1 is turned round to measure it1 and exactly fits it4 ,but while ,a is satisfied1 ,b declares that has changed in exactly the same way as did 4 ,meanwhile ,b has procured two material rods satisfactory to him as invariable1 and ,a makes exactly the same objections4 ,we shall say that ,a and ,b employ diverse ,euclidean metrical systems4 ,the most extraordinary fact of human life is that all beings seem to form their judgments of spatial quantity according to the same metrical system4 ,relativity in ,modern ,physics ,owing to the fact that points of space are incapable of direct recognition1 there is a difficulty--apart from any abstract question of the nature of space--in deciding on the motion to be ascribed to any body4 ,even if there be such a thing as absolute position1 it is impossible in practice to decide directly whether a body's absolute position has changed4 ,all spatial measurement is relative to matter4 ,newton's laws of motion in their modern dress evade this difficulty by asserting that a framework of axes of coordinates can be defined by their relations to matter such that1 assuming these axes to be at rest1 and all velocities to be measured relatively to them1 the laws hold4 ,the same expedient has to be employed for time1 namely1 the laws hold when the measurement of the flow of time is made by the proper reference to periodic events4 ,thus the laws assert that the framework and the natural clock adapted for their use have been successfully found4 ,but1 if one framework will do1 an infinity of others serve equally well2 namely1 not only--as is of course the case--all those at rest relatively to the first framework1 but also all those which move without relative rotation with uniform velocity relatively to the first4 ,this whole set of frameworks is on a level in respect to ,newton's laws4 ,we will call them ,dynamical frameworks4 ,now1 suppose there are two observers1 ,a and ,b4 ,they agree in their non-metrical projective geometry1 e4g41 what ,a calls a straight line so does ,b4 ,they also both apply a ,euclidean metrical system of measurement to this space4 ,their two metrical systems also agree in having the same plane at infinity1 that is1 lines which are parallel for ,a are also parallel for ,b4 ,furthermore1 they have both successfully applied ,newton's laws to the movement of matter1 and agree in having the same sets of dynamical axes4 ,but the framework 7among these sets7 which ,a chooses to regard as at rest is different from the frame 7among the same sets7 which ,b so regards4 ,without alteration of their respective judgment of rest1 they choose their co-ordinate axes so that the origins 7,o for ,a1 and ,o for ,b7 are in relative motion along ,,oo1 which is the axis of x for both4 ,further1 since ,,oo is the line of symmetry of their diverse ,euclidean systems1 we assume that the two measure-systems agree for planes perpendicular to ,,oo1 i4e41 we assume a symmetry round ,,oo4 ,then if1 for ,a at ,o1 the distance ,,oo be 1 the relations at any instant between ,a's coordinates 7x1 y1 z7 and ,b's coordinates 7x1 y1 z7 for the same point ,p are given by x 7x - 71 y y1 z z4 ,also1 according to ,a's clock1 ,o is moving forward with a uniform velocity v1 and we measure ,a's time from the instant of the coincidence of ,o and ,o4 ,thus vt1 and x 7x - vt71 y y1 z z4 ,we now consider ,b's clock1 and ask for the most general supposition which is consistent with the fact that their judgments as to the fact of uniform motion are in agreement4 ,we do not assume that events in various parts of space which ,a considers to be simultaneous are so considered by ,b4 ,but we assume that at any point ,p1 with coordinates 7x1 y1 z7 for ,a1 there is a determinate relation between ,b's time ,t and x1 y1 z1 t4 ,put ,t 7x1 y1 z1 t74 ,write ,p ,t_/x1 ,q ,t_/y1 ,r ,t_/z1 ,s ,t_/t4 ,now suppose that the point ,p is moving1 and that 7u#a1 u#b1 u#c7 is its set of component velocities along the axes according to ,a's space and clock system1 and 7,u#a1 ,u#b1 ,u#c7 is its set of component velocities according to ,b's space and clock system4 ,then by mere differentiation it follows after a short mathematical deduction that ,u#a 7d_/dt77x - vt7 7u#a - v7_/,pu#a ,qu#b ,ru#c ,s1 ,u#b u#b_/,pu#a ,qu#b ,ru#c ,s1 ,u#c u#c_/,pu#a ,qu#b ,ru#c ,s4 ,but we have assumed that1 whatever the direction of the resultant velocity 7u#a1 u#b1 u#c71 the velocities 7,u#a1 ,u#b1 ,u#c7 and 7u#a1 u#b1 u#c7 are both uniform when either is uniform4 ,hence it is easily proved that 1 ,p1 ,q1 ,r1 ,s are independent of the coordinates 7x1 y1 z7 and of the time t4 ,in other words1 they are constant4 ,hence we obtain ,u#a 7u#a - v7_/,pu#a ,qu#b ,ru#c ,s1 and ,t ,px ,qy ,rz ,st4 ,but we assumed that ,,oo1 i4e41 ,ox1 is an axis of symmetry4 ,it follows from this assumption that ,q ,r #j4 ,we thus obtain the simplified results ,t ,px ,st1 ,u#a 7u#a - v7_/7,pu#a ,s71 7,i7 ,u#b u#b_/7,pu#a ,s71 ,u#c u#c_/7,pu#a ,s74 ,here we remember that 7u#a1 u#b1 u#c7 are the velocities of any particle according to ,a's space and clock system1 and that 7,u#a1 ,u#b1 ,u#c7 are the velocities of the same point according to ,b's space and clock system4 ,we have obtained the most general relations consistent with the facts that 7#a7 they both employ ,euclidean systems1 related as described above1 and 7#b7 they agree in their judgments on the uniformity of velocity4 ,we now compare their judgments on the magnitudes of velocities4 ,let the magnitude of the velocity of ,p be ,v according to ,a's judgment1 and ,v according to ,b's' judgment4 ,then ,v#b u#ab u#bb u#cb1 ,v#b ,u#ab ,u#bb ,u#cb4 ,also we can put u#a l,v1 u#b m,v1 u#c n,v1 where 7l1 m1 n7 have nothing to do with the magnitude ,v1 but simply depend on the direction of motion4 ,in fact 7l1 m1 n7 are the direction cosines of the velocity according to ,a's judgment4 ,by substituting in the above equation for ,v#b we see that l#b m#b n#b #a4 ,now1 substituting for 7u#a1 u#b1 u#c7 in the equations 7,i7 above1 and squaring and adding1 and eliminating m#b n#b by the relation just found1 we at once find ,v#b 77#b - #a7,v#bl#b - #bb,vvl #bv#b ,v#b7_/7,,pvl ,s7#b4 ,it is thus seen that in general the relation of ,v to ,v depends on the direction cosine l4 ,now l is the cosine of the angle which the direction of the velocity ,v makes with ,ox1 according to ,a's judgment4 ,the meaning of this relation is1 that if ,a discharges1 from guns at the point ,p1 shells with a given muzzle velocity ,v according to his judgment1 ,b will consider that their muzzle velocities are different from each other1 except in the case of pairs of guns equally inclined to the axis ,,oo4 ,instances of this type of diversity of judgment can be noted any day by any one who looks out of the window of a railway carriage1 and forgets that he is travelling4 ,now1 suppose the velocity ,v bears a relation to the velocity ,v1 which is independent of l4 ,then l must disappear from the above formula4 ,there are two conditions to be satisfied ,one condition is ,v#b #bv#b_/7b - #a71 or in a more convenient form #b #a_/7a - v#b_/,v#b74 ,the meaning of this condition is1 that there is one1 and only one1 muzzle velocity ,v 7according to ,a's judgment71 namely1 the muzzle velocity given by the above formula1 which can have the property that ,b will judge that all the guns are firing in their diverse directions with one common muzzle velocity4 ,let us now suppose that ,v has this peculiar value3 that is1 if we look on this value ,v as known1 we must suppose that is given by the second of the above formul4 ,the other condition allows ,p and ,s to be put in the forms ,p -v_/,v#b1 ,s _/1 where ,v ,v4 ,thus we have the bundle of formul #b #a_/7a - v#b_/,v#b71 ,t t - vx_/,v#b_/1 ,v ,v4 ,the value which we give to is purely a matter for the adjustment of units4 ,if we want ,a and ,b to agree in their judgments of the magnitude of this peculiar muzzle-velocity1 we put #a4 ,we then get the formul usually adopted1 namely #b #a_/7a - v#b_/,v#b71 ,t t - vx_/,v#b1 7,,ii7 ,v ,v4 ,but if we prefer that ,a and ,b should reckon 7according to ,a's judgment7 in the same units of time1 we put 1 and obtain #b #a_/7a - v#b_/,v#b71 ,t 7t - vx7_/,v#b1 ,v ,v4 ,but ,a and ,b are in any case in such hopeless difficulties over their comparisons of time-judgments that the detail of using the same units does not help them much4 ,accordingly the formul marked 7,,ii7 are those used4 ,thus ,a and ,b agree in their judgments as to the magnitude of one special velocity ,v1 whatever may be the direction in which the entity possessing it is moving4 ,in order to reach this measure of agreement1 they have to disagree as to their space judgments and their time judgments4 ,the root cause of their disagreement is their diverse judgment as to which axis system is to be taken at rest for the purpose of measuring velocities4 ,before discussing the nature of the disagreement disclosed in formula 7,,ii71 let us ask why we should bring these difficulties on our heads by supposing that two people in relative motion1 who both 7for the purpose of measuring velocities7 assume that they are at rest1 should agree in their judgments in respect to this special velocity ,v4 ,such an agreement has no counterpart in any of our obvious judgments made from railway carriages4 ,surely we can wait till the contingency occurs before discussing the confusion which it creates4 ,but the contingency has occurred4 ,it occurs when we consider the velocity of light4 ,perhaps ,i may venture to remind a philosophical society that light moves so very quickly that it is difficult to consider its velocity at all4 ,so we need not be surprised that this peculiar fact concerning its velocity is not more obvious4 ,now ,v being the velocity of light1 unless v is large1 v_/,v 7and still more v#b_/,v#b7 will be quite inappreciable4 ,the only velocity ready to hand which is big enough to give v_/,v an appreciable value is the velocity of the earth in its orbit4 ,many diverse experiments have been made1 and they all agree in concluding that a man who assumes the earth to be at rest will find by measurement that the velocity of light is the same in all directions4 ,furthermore1 when the same man turns his attention to interstellar or interplanetary phenomena1 and assumes the sun to be at rest1 he will again find the velocity of light to be the same in all directions4 ,these are well-attested experiments made at long intervals of time4 ,this is the exact contingency contemplated above4 ,again the velocity of light in vacuo has recently taken on a new dignity4 ,it used to be one among other wave velocities such as the velocity of sound in air1 or in water1 or the velocity of surface waves in water4 ,but ,clerk ,maxwell discovered that all electromagnetic influences are propagated with the velocity of light1 and now modern physical science half suspects that electromagnetic influences are the only physical influences which relate the changes in the physical world4 ,accordingly the velocity of light becomes the fundamental natural velocity1 and experiment shows that our judgment of its magnitude is not affected by our choice of the framework at rest1 so long as we keep to a set of dynamical axes4 ,these experiments on light have been confirmed by other electromagnetic experiments not involving light4 ,thus we are driven to equations 7,,ii71 where ,v is the velocity of light4 ,the first conclusion to be drawn from equations 7,,ii7 is that two people who make different choices of bodies at rest will disagree as to their measuring rods in the way described above4 ,there is no peculiar difficulty about that4 ,the only wonder is that all people agree so well in their judgments as to metrical systems4 ,a mathematical angel would naturally expect incarnate men to be in violent disagreement on this subject4 ,but the case of time is different4 ,for simplicity of statement we speak of ,a as at ,o1 and ,b as at ,o4 ,we remember that ,o is moving relatively to ,o with velocity v in direction ,,oo4 ,suppose ,a and ,b are looking in this direction2 and they both measure their time from the instant when they met1 as ,o passed over ,o4 ,then we have ,t 77t - vx7_/,v#b7_/77a - v#b7_/,v#b74 ,now1 suppose we consider all the events all over space which ,a considers to have happened simultaneously at the time t4 ,the events of this set which occurred anywhere on a plane perpendicular to ,,oo at a distance x in front of ,o 7according to ,a's reckoning71 will have occurred according to ,b's reckoning at the time ,t as given above4 ,let us fix our attention on the fact that ,b does not consider all these events to be simultaneous4 ,for let ,t#a1 and ,t#b be ,b's times for such events on planes x#a1 and x#b4 ,then ,t#a - ,t#b v7x#b - x#a7_/7,v#b - v#b74 ,thus if x#b be greater than x#a1 ,t#b is less than ,t#a4 ,thus ,b judges the more distant events in front of him to have happened earlier than the nearer events in front of him1 and vice versa for the events behind4 ,this disturbance of the judgment of simultaneity is the fundamental fact4 ,obviously the measurement of time intervals is a detail compared to simultaneity4 ,a may think a sermon long1 and ,b may think it short1 but at least they should both agree that it stopped when the clock hand pointed at the hour4 ,the worst of the matter is that so far as any test can be applied there is no method of discriminating between the validities of their judgments4 ,thus we are confronted with two distinct concepts of the common world1 ,a's space-time concept1 and ,b's space-time concept4 ,who is right8 ,it is no use staying for an answer4 ,we must follow the example of the wise old ,roman1 and pass on to other things4 ,thus estimates of quantity in space and time1 and1 to some extent1 even estimates of order1 depend on the individual observer4 ,but what are the crude deliverances of sensible experience1 apart from that world of imaginative reconstruction which for each of us has the best claim to be called our real world8 ,here the experimental psychologist steps in4 ,we cannot get away from him4 ,i wish we could1 for he is frightfully difficult to understand4 ,also1 sometimes his knowledge of the principles of mathematics is rather weak1 and ,i sometimes suspect---- ,no1 ,i will not say what ,i sometimes think3 probably he1 with equal reason1 is thinking the same sort of thing of us4 ,i will1 however1 venture to summarise conclusions1 which are1 ,i believe1 in harmony with the experimental evidence1 both physical and psychological1 and which are certainly suggested by the materials for that unwritten chapter in mathematical logic which ,i have already commended to your notice4 ,the concepts of space and time and of quantity are capable of analysis into bundles of simpler concepts4 ,in any given sensible experience it is not necessary1 or even usual1 that the whole complete bundle of such concepts apply4 ,for example1 the concept of externality may apply without that of linear order1 and the concept of linear order may apply without that of linear distance4 ,again1 the abstract mathematical concept of a space-relation may confuse together distinct concepts which apply to the given perceptions4 ,for example1 linear order in the sense of a linear projection from the observer is distinct from linear order in the sense of a row of objects stretching across the line of sight4 ,mathematical physics assumes a given world of definitely related objects1 and the various space-time systems are alternative ways of expressing those relations as concepts in a form which also applies to the immediate experience of observers4 ,yet there must be one way of expressing the relations between objects in a common external world4 ,alternative methods can only arise as the result of alternative standpoints2 that is to say1 as the result of leaving something added by the observer sticking 7as it were7 in the universe4 ,but this way of conceiving the world of physical science1 as composed of hypothetical objects1 leaves it as a mere fairy tale4 ,what is really actual are the immediate experiences4 ,the task of deductive science is to consider the concepts which apply to these data of experience1 and then to consider the concepts relating to these concepts1 and so on to any necessary degree of refinement4 ,as our concepts become more abstract1 their logical relations become more general1 and less liable to exception4 ,by this logical construction we finally arrive at conceptions1 7i7 which have determinate exemplifications in the experience of the individuals1 and 7ii7 whose logical relations have a peculiar smoothness4 ,for example1 conceptions of mathematical time1 of mathematical space1 are such smooth conceptions4 ,no one lives in an infinite given whole1 but in a set of fragmentary experiences4 ,the problem is to exhibit the concepts of mathematical space and time as the necessary outcome of these fragments by a process of logical building up4 ,similarly for the other physical concepts4 ,this process builds a common world of conceptions out of fragmentary worlds of experience4 ,the material pyramids of ,egypt are a conception1 what is actual are the fragmentary experiences of the races who have gazed on them4 ,so far as science seeks to rid itself of hypothesis1 it cannot go beyond these general logical constructions4 ,for science1 as thus conceived1 the divergent time orders considered above present no difficulty4 ,the different time systems simply register the different relations of the mathematical construct to those individual experiences 7actual or hypothetical7 which could exist as the crude material from which the construct is elaborated4 ,but after all it should be possible so to elaborate the mathematical construct so as to eliminate specific reference to particular experiences4 ,whatever be the data of experience1 there must be something which can be said of them as a whole1 and that something is a statement of the general properties of the common world4 ,it is hard to believe that with proper generalisation time and space will not be found among such properties4 ,commentary added on reading the ,paper before the ,aristotelian ,society ,the first six pages of the paper consist of a summary of ideas which ought to be in our minds while considering problems of time and space4 ,the ideas are mostly philosophical1 and the summary has been made by an amateur in that science2 so there is no reason to ascribe to it any importance except that of a modest reminder4 ,there are only two points in this summary to which ,i would draw attention4 ,on pp4 #aib and #aic there occurs-- ,wherever mankind 444 unending uniform succession4 ,if ,i understand ,kant rightly--which ,i admit to be very problematical--he holds that in the act of experience we are aware of space and time as ingredients necessary for the occurrence of experience4 ,i would suggest--rather timidly--that this doctrine should be given a different twist1 which in fact turns it in the opposite direction--namely1 that in the act of experience we perceive a whole formed of related differentiated parts4 ,the relations between these parts possess certain characteristics1 and time and space are the expressions of some of the characteristics of these relations4 ,then the generality and uniformity which are ascribed to time and space express what may be termed the uniformity of the texture of experience4 ,the success of mankind--modest though it is--in deducing uniform laws of nature is1 so far as it goes1 a testimony that this uniformity of texture goes beyond those characteristics of the data of experience which are expressed as time and space4 ,time and space are necessary to experience in the sense that they are characteristics of our experience2 and1 of course1 no one can have our experience without running into them4 ,i cannot see that ,kant's deduction amounts to much more than saying that what is1 is--true enough1 but not very helpful4 ,but ,i admit that what ,i have termed the uniformity of the texture of experience is a most curious and arresting fact4 ,i am quite ready to believe that it is a mere illusion2 and later on in the paper ,i suggest that this uniformity does not belong to the immediate relations of the crude data of experience1 but is the result of substituting for them more refined logical entities1 such as relations between relations1 or classes of relations1 or classes of classes of relations4 ,by this means it can be demonstrated--,i think--that the uniformity which must be ascribed to experience is of a much more abstract attenuated character than is usually allowed4 ,this process of lifting the uniform time and space of the physical world into the status of logical abstractions has also the advantage of recognising another fact1 namely1 the extremely fragmentary nature of all direct individual experience4 ,my point in this respect is that fragmentary individual experiences are all that we know1 and that all speculation must start from these disjecta membra as its sole datum4 ,it is not true that we are directly aware of a smooth running world1 which in our speculations we are to conceive as given4 ,in my view the creation of the world is the first unconscious act of speculative thought2 and the first task of a self-conscious philosophy is to explain how it has been done4 ,there are roughly two rival explanations4 ,one is to assert the world as a postulate4 ,the other way is to obtain it as a deduction1 not a deduction through a chain of reasoning1 but a deduction through a chain of definitions which1 in fact1 lifts thought on to a more abstract level in which the logical ideas are more complex1 and their relations are more universal4 ,in this way the broken limited experiences sustain that connected infinite world in which in our thoughts we live4 ,there are three more remarks while on this point ,i wish to make-- 7i7 ,the fact that immediate experience is capable of this deductive superstructive must mean that it itself has a certain uniformity of texture4 ,so this great fact still remains4 7ii7 ,i do not wish to deny the world as a postulate4 ,speaking without prejudice1 ,i do not see how in our present elementary state of philosophical advance we can get on without middle axioms1 which1 in fact1 we habitually assume4 ,my position is1 that by careful scrutiny we should extrude such postulates from every part of our organised knowledge in which it is possible to do without them4 ,now1 physical science organises our knowledge of the relations between the deliverances of our various senses4 ,i hold that in this department of knowledge such postulates1 though not entirely to be extruded1 can be reduced to a minimum in the way which ,i have described4 ,i have not the slightest knowledge of theories respecting our emotions1 affections1 and moral sentiments1 and ,i can well believe that in dealing with them further postulates are required4 ,and in practice ,i recognise that we all make such postulates1 uncritically4 7iii7 ,the next paragraphs on pp4 #aic and #aid are as follows-- ,the opposed philosophical method 444 physical science4 ,it will be noted that1 in the light of what has just been stated1 the first of these paragraphs 7which1 ,i hope1 faithfully expresses the experimental way of approaching the problem7 really obscures the point which ,i have been endeavouring to make4 ,the phrase1 ,if we form the exact concepts of points1 etc41 is fatally ambiguous as between the method of postulating entities with assigned relations1 and the method of forming logical constructions1 and thus reaching points1 etc41 as the result of a chain of definitions4 ,turning now to pp4 #aid-aie1 we come to the following paragraphs-- ,the other theory 444 eighteenth century4 ,we note again that the relational theory of space from another point of view brings us back to the idea of the fundamental space-entities as being logical constructs from the relations between things4 ,the difference is1 that this paragraph is written from a more developed point of view1 as it implicitly assumes the things in space1 and conceives space as an expression of certain of their relations4 ,combining this paragraph with what has gone before1 we see that the suggested procedure is first to define things in terms of the data of experience1 and then to define space in terms of the relations between things4 ,this procedure is explicitly assumed in the next short paragraph3 ,in this connection 444 from the events4 ,the gist of the remaining paragraphs of this section is contained in the paragraph at the bottom of p4 #aif3 ,the point in time 444 new importance4 ,the sentence1 ,we live in durations1 and not in points1 can be amplified by the addition1 ,we live in space-extensions and not in space-points4 ,it must be noted that whole and part as applied to extensions in space or time must be different from the all and some of logic1 unless we admit points to be the fundamental entities4 ,for spatial whole and spatial part can only mean all and some if they really mean all the points and some of the points4 ,but if extensions and their relations are more fundamental than points1 this interpretation is precluded4 ,i suggest that spatial whole and spatial part is intimately connected with the fundamental relation between things from which our space ideas spring4 ,the relation of space whole to space part has many formal properties which are identical with the properties of all and some4 ,also when points have been defined1 we can replace it by the conception of all the points and some of the points4 ,but the confusion between the two relations is fatal to sound views on the subject4 ,diverse ,euclidean ,measure ,systems ,the next section deals with the measure systems applicable to space4 ,a measure system is a group of congruent transformations of space into itself4 ,consider a rigid body occupying all space4 ,let this body be moved in any way so that the particles of the body which occupied points ,p#a1 ,p#b1 ,p#c1 etc41 now occupy points ,q#a1 ,q#b1 ,q#c1 etc4 ,then any point ,p#a in space is uniquely related to the corresponding point ,q#a in space by a one-to-one transformation with certain characteristics4 ,by the aid of these transformations we can achieve the definition of distance in a way which definitely determines the distance between any two points1 provided that we can define what we mean by a congruent transformation without introducing the idea of distance4 ,if we introduced the idea of distance1 we should simply say that a congruent transformation is one which leaves all distances unchanged1 i4 e41 if ,p#a1 ,p#b are transformed into ,q#a1 ,q#b then the distance ,p#a,p#b is equal to the distance ,q#a,q#b4 ,but mathematicians have succeeded in defining congruent transformations without any reference to distance4 ,there are alternative groups of such congruent transformations1 and each group gives a different measure system for space4 ,the distance ,p#a,p#b may equal the distance ,q#a,q#b for one measure system1 and will not equal it for another measure system4 ,all these different measure systems are on the same level1 equally applicable4 ,a being with a strong enough head could think of them all at once as applying to space4 ,the result so far as it interests us in respect to the theory of relativity is explained on pp4 #aig-bjj1 ending with ,the most extraordinary fact 444 same metrical system4 ,this final sentence bears on ,poincar's assertion that the measure system adopted is purely conventional4 ,i presume that by conventional a certain arbitrariness of choice is meant2 and in that case1 ,i must express entire dissent4 ,it is true that within the circle of geometrical ideas there is no means of giving any preference to any one measure system1 and any one is as good as any other4 ,but it is not true that if we look at a normal carriage wheel1 and at an oval curve one foot broad and ten feet long1 we experience any arbitrariness of judgment in deciding which has approximately the form of a circle4 ,accordingly to ,poincar the choice between them1 as representing a circle1 is entirely conventional4 ,again1 we equally form immediate judgments as to whether a body is approximately rigid4 ,we know that a paving stone is rigid1 and that a concertina is not rigid4 ,this again necessitates a determinate measure system1 selected from among the others4 ,accordingly we conclude that 7i7 each being does1 in fact1 employ a determinate measure system1 which remains the same1 except possibly for very small variations1 and 7ii7 the measure systems of different human beings agree1 to within the limits of our observations4 ,these conclusions are not the less extraordinary because no plain man has ever doubted them4 ,it is an interesting subject to investigate exactly what are the fundamental uniformities of experience which necessitate this conclusion4 ,it is not so easy as it looks1 since we have to divest ourselves of all aid of scientific hypothesis if our conclusions are to be demonstrative4 ,relativity in ,modern ,physics ,pp4 #bja-bjb1 ,owing to the fact 444 which ,b so regards4 ,the fundamental formul for the theory of relativity are the relations between diverse co-ordinate systems given on p4 #bjc1 and formul ,,ii at the bottom of p4 #bjg4 ,the general explanation of one method in which these formul arise--namely1 ,einstein's method--is given on pp4 #bja-baa4 ,namely1 we seek the condition that for all dynamical axes the velocity of light should be the same1 and the same in all directions4 ,it should be noted that the experiments which1 so far as they go1 confirm these formul1 can also be explained in another way which makes the theory of relativity unnecessary4 ,we need only ascribe to the ether a certain property of contraction in the direction of motion1 and the thing is done4 ,so no one need be bludgeoned into accepting the rather bizarre doctrine of relativity1 nor indeed any other scientific generalisation4 ,the good old homely ether1 which we all know1 can in this case serve the purpose4 ,just as an author of genius1 if he lives long enough1 survives the inevitable accusation of immorality1 so the ether by dint of persistence has outlived all reputation of extravagance4 ,but if we detach ourselves from the glib phraseology concerning it1 the scientific ether is uncommonly like the primitive explanation of the soul1 as a little man inside us1 which can sometimes be caught escaping in the form of a butterfly4 ,as soon as the ether has to be patched up with special properties to explain special experiments1 its scientific use is problematical1 and its philosophic use is nil4 ,philosophically the ether seems to me to be an ambitious attempt to give a complete explanation of the physical universe by making an elephant stand on a tortoise4 ,scientifically it has a perfectly adequate use by veiling the extremely abstract character of scientific generalisations under a myth1 which enables our imaginations to work more freely4 ,i am not advocating the extrusion of ether from our scientific phraseology1 even though at special points we have to abandon it4 ,but the key to the reasons why it is worth while to consider seriously the doctrine of relativity is to be found on pp4 #bji1 #baj3 ,again the velocity of light 444 not involving light4 ,namely1 we have begun to suspect that all physical influences require time for their propagation in space4 ,this generalisation is a long way from being proved4 ,gravitation stands like a lion in the path4 ,but if it be the case1 then all idea of an immediate presentation to us of an aspect of the world as it in fact is1 must necessarily be abandoned4 ,what we perceive at any instant is already ancient history1 with the dates of the various parts hopelessly mixed4 ,we must add to this the difficulty of determining what is at rest and what is in motion1 and the further difficulty of determining a definite uniform flow of time4 ,it is no use discussing this matter as though1 but for the silly extravagant doctrine of relativity1 everything would be plain sailing4 ,it isn't4 ,you may be quite sure that when1 after prolonged study1 you endeavour to give the simplest explanation of a grave difficulty1 you will be accused of extravagance4 ,i have no responsibility for the doctrine of relativity1 and hold no brief for it1 but it has some claim to be considered as a comparatively simple way out of a scientific maze4 ,in the first place1 we use the ,newtonian dynamical sets of axes1 and the ,newtonian clock to extricate ourselves partially from the difficulties of rest1 motion1 and time4 ,these have proved capable of scientific determination within the limits of our experimental accuracy4 ,thus the only thing left over is the choice of the axes at rest1 which is a completely indeterminate problem on ,newtonian principles4 ,again1 so far as we can at present guess by adopting the theory that all metrical influence is electromagnetic1 all influences are propagated with the velocity of light in vacuo4 ,this electromagnetic hypothesis is by no means established1 but it gives the simplest of all possible results in respect to the propagation of influence1 which we therefore adopt4 ,but what dynamical axes are we taking as at rest8 ,now our practical choice gives a range of relative velocities small compared to that of light4 ,so except for certain refined experiments it does not matter4 ,there are two possibilities-- 7i7 ,we may assume that one set of axes are at rest1 and that the others will show traces of motion in respect to the velocity of light2 or-- 7ii7 ,that the velocity of light is the same in all directions whichever be the dynamical axes assumed4 ,the first supposition is negatived by experiment1 and hence we are driven to the second supposition2 which immediately lands us in the whole theory of relativity4 ,but if we will not have this theory we must reject the earlier supposition that the velocity of light in vacuo is the same in all directions4 ,this we do1 in fact1 by assuming an ether1 and assuming a certain law for its modification4 ,then we1 in fact1 adopt the first supposition so far as to hold that there are dynamical axes specially at rest1 namely1 at rest relatively to the undisturbed ether4 ,then an assumed law for the modification of the ether so alters the velocity of light that we explain why no dynamical axes show traces of motion4 ,i wish now to go back to the point which ,i made a few minutes ago1 that what we perceive at any instant is ancient history with its dates hopelessly mixed4 ,in the earlier part of my comments ,i emphasised the point that our only data as to the physical world are our sensible perceptions4 ,we must not slip into the fallacy of assuming that we are comparing a given world with given perceptions of it4 ,the physical world is in some general sense of the term a deduced concept4 ,our problem is1 in fact1 to fit the world to our perceptions1 and not our perceptions to the world4 ,,printed ,,in ,,great ,,britain ,,by ,,richard ,,clay ,,sons1 ,,limited1 ,,brunswick ,,st41 ,,stamford ,,st41 ,s4,e41 ,,and ,,bungay1 ,,suffolk4 ,from ,,williams ,,norgate',s ,,list ,a ,,spiritual ,,pilgrimage4 ,by the ,rev4 ,r4 ,j4 ,,campbell4 7,the ,rev4 ,r4 ,j4 ,campbell's own ,story of his ,religious ,life47 #bnd ,impression4 ,demy #hvo4 #gs4 #f;d4 net4 ,this is eminently a book for which to be thankful--simple1 straightforward1 kindly4 ,neither does it lack the saving grace of humour4--,guardian4 ,mr4 ,campbell devotes a chapter to his re-ordination1 and it must be admitted that his defence of this act is effective4--,methodist ,times4 ,,edinburgh4 ,by the ,right ,hon4 ,sir ,,herbert ,,maxwell1 ,bart41 ,d4,c4,l41 ,author of ,life of the ,duke of ,wellington1 ,scottish ,gardens1 etc4 ,president of the ,society of ,antiquaries of ,scotland1 #aiaj-ac1 and ,chairman of the ,royal ,commission on ,scottish ,historical ,monuments4 ,with a ,coloured ,frontispiece and #fd pages of ,illustrations of the past and present city4 ,medium #hvo4 #ajs4 #f;d4 net4 ,a ,history of the ,scottish ,capital from the earliest times to the nineteenth century4 ,,further ,,pages ,,of ,,my ,,life4 ,by the ,right ,rev4 ,w4 ,,boyd ,,carpenter1 ,k4,c4,v4,o41 ,d4,d41 ,d4,c4,l41 ,formerly ,bishop of ,ripon1 ,author of ,some ,pages of ,my ,life1 ,the ,witness of ,religious ,experience1 etc4 ,with ,illustrations4 ,medium #hvo4 #ajs4 #f;d4 net4 ,reflections mingled with intimate reminiscences and recollections of ,royal personages and of men eminent in many spheres4 ,,some ,,pages ,,of ,,my ,,life4 ,by the ,right ,rev4 ,w4 ,,boyd ,,carpenter4 ,new and ,cheaper ,edition4 ,large post #hvo4 #es4 net4 ,all who have listened to his eloquent preaching will read with delight his musing on what life has brought the author4 ,,raphael ,,meldola1 ,hon4 ,d4,sc4 7,oxon471 ,hon4 ,,ll4,d4 7,st4 ,and471 ,f4,r4,s41 ,professor of ,chemistry in the ,city and ,guilds of ,london ,technical ,college4 ,reminiscences of his worth and work1 by those who knew him1 together with a ,chronological ,list of his ,publications 7#ahfh-aiae74 ,edited by ,,james ,,marchant4 ,with a ,preface by the ,right ,hon4 ,,lord ,,moulton1 ,k4,c4,b41 ,f4,r4,s4 ,with a ,portrait4 ,crown #hvo4 #es4 net4 ,the book is one of the most delightful biographies of scientific men that have been published during recent years4--,chemist and ,druggist4 ,,the ,,manufacture ,,of ,,historical ,,material4 ,an ,elementary ,study in the ,sources of ,story4 ,by ,j4 ,w4 ,,jeudwine1 ,,ll4,b4 7,camb471 of ,lincoln's ,inn1 ,barrister-at-,law1 ,author of ,the ,first ,twelve ,centuries of ,british ,story1 and other works4 ,crown #hvo4 #fs4 net4 ,a consideration of the successive phases of ,historical ,research2 it explains necessary processes through which all the material has to pass before it is placed before us as history4 ,,london3 ,,williams ,,and ,,norgate ,,some ,,books ,,on ,,russia ,,and ,,poland ,with a ,coloured ,frontispiece1 #ab ,photogravure ,plates1 #bh ,illustrations in the text1 and #h ,maps4 ,demy #hvo4 #gs4 #f;d4 net 7postage #f;d4 extra74 ,a ,thousand ,years of ,russian ,history ,by ,,sonia ,e4 ,,howe4 ,we can recommend the volume as an excellent1 careful1 and well-written history of a great nation4--,daily ,telegraph4 ,demy #hvo4 ,cloth1 #fs4 net4 ,the ,false ,dmitri ,a ,russian ,romance and ,tragedy4 ,described by ,british ,eye-witnesses1 #afjd-afab4 ,edited with a ,preface by ,,sonia ,e4 ,,howe4 ,illustrated by reproduction of contemporary portraits4 ,with more than a whiff of the atmosphere ,hakluyt got into his famous volume4--,northern ,whig4 ,of special interest at the present time4--,oxford ,chronicle4 ,with #af ,plates and #bh ,illustrations in the text4 ,demy #hvo4 #gs4 #f;d4 net4 ,some ,russian ,heroes1 ,saints and ,sinners ,a portrait gallery of outstanding figures in ,russian history who were typical of their times and their country4 ,by ,,sonia ,e4 ,,howe4 ,it gives a vivid study of ,russia 444 and interesting book4--,land and ,water4 ,fcap4 #hvo4 ,cloth1 #as4 #c;d4 net4 ,in full leather presentation binding1 #bs4 #f;d4 net4 ,an ,outline of ,russian ,literature ,by the ,hon4 ,,maurice ,,baring1 ,author of ,with the ,russians in ,manchuria1 ,a ,year in ,russia1 ,the ,russian ,people1 etc4 ,gives a clear and interesting account of the growth of ,russian literature4 ,fcap4 #hvo4 ,cloth1 #as4 #c;d4 net4 ,in full leather binding1 #bs4 #f;d4 net4 ,poland ,by ,w4 ,,alison ,,phillips1 ,m4,a41 ,lecky ,professor of ,modern ,history in the ,university of ,dublin4 ,a concise survey of the ,history of ,poland up to #aiae4 ,,london3 ,,williams ,,and ,,norgate #ad ,,henrietta ,,street1 ,,covent ,,garden1 ,w4,c4 ,,transcriber',s ,,notes ,simple typographical errors have been silently corrected2 unbalanced quotation marks were remedied when the change was obvious1 and otherwise left unbalanced4 ,punctuation1 hyphenation1 and spelling were made consistent when a predominant preference was found in the original book2 otherwise they were not changed4