,,contributions ,,from ,,the ,,museum ,,of ,,history ,,and ,,technology3 ,,paper #h ,,the ,,natural ,,philosophy ,,of ,,william ,,gilbert ,,and ,,his ,,predecessors ,w4 ,james ,king ,by ,w4 ,james ,king ,,the ,,natural ,,philosophy ,,of ,,william ,,gilbert ,,and ,,his ,,predecessors ,until several decades ago1 the physical sciences were considered to have had their origins in the #agth century--mechanics beginning with men like ,galileo ,galilei and magnetism with men like the ,elizabethan physician and scientist ,william ,gilbert4 ,historians of science1 however1 have traced many of the #agth century's concepts of mechanics back into the ,middle ,ages4 ,here1 ,gilbert's explanation of the loadstone and its powers is compared with explanations to be found in the ,middle ,ages and earlier4 ,from this comparison it appears that ,gilbert can best be understood by considering him not so much a herald of the new science as a modifier of the old4 ,,the ,,author3 ,w4 ,james ,king is curator of electricity1 ,museum of ,history and ,technology1 in the ,smithsonian ,institution's ,united ,states ,national ,museum4 ,the year #afjj saw the publication by an ,english physician1 ,william ,gilbert1 of a book on the loadstone4 ,entitled ,de magnete1#a it has traditionally been credited with laying a foundation for the modern science of electricity and magnetism4 ,the following essay is an attempt to examine the basis for such a tradition by determining what ,gilbert's original contributions to these sciences were1 and to make explicit the sense in which he may be considered as being dependent upon earlier work4 ,in this manner a more accurate estimate of his position in the history of science may be made4 #a ,william ,gilbert1 ,de magnete1 magneticisque corporibus et de magno magnete tellure2 physiologia nova1 plurimis argumentis1 experimentis1 demonstrata1 ,london1 #afjj1 #bdj pp41 with an introduction by ,edward ,wright4 ,all references to ,gilbert in this article1 unless otherwise noted1 are to the ,american translation by ,p4 ,fleury ,mottelay1 #cfh pp41 published in ,new ,york in #ahic1 and are designated by the letter ,m4 ,however1 the ,latin text of the #afjj edition has been quoted wherever ,i have disagreed with the ,mottelay translation4 ,a good source of information on ,gilbert is ,dr4 ,duane ,h4 ,d4 ,roller's doctoral thesis1 written under the direction of ,dr4 ,i4 ,b4 ,cohen of ,harvard ,university4 ,dr4 ,roller1 at present ,curator of the ,de ,golyer ,collection at the ,university of ,oklahoma1 informed me that an expanded version of his dissertation will shortly appear in book form4 ,unfortunately his researches were not known to me until after this article was completed4 ,one criterion as to the book's significance in the history of science can be applied almost immediately4 ,a number of historians have pointed to the introduction of numbers and geometry as marking a watershed between the modern and the medieval understanding of nature4 ,thus ,a4 ,koyr considers the ,archimedeanization of space as one of the necessary features of the development of modern astronomy and physics4#b ,a4 ,n4 ,whitehead and ,e4 ,cassirer have turned to measurement and the quantification of force as marking this transition4#c ,however1 the obvious absence#d of such techniques in ,de magnete makes it difficult to consider ,gilbert as a founder of modern electricity and magnetism in this sense4 #b ,alexandre ,koyr1 tudes galilennes1 ,paris1 #aici4 #c ,alfred ,n4 ,whitehead1 ,science and the modern world1 ,new ,york1 #aibe1 ch4 #c2 ,ernst ,cassirer1 ,das ,erkenntnisproblem1 ed4 #c1 ,berlin1 #aibb1 vol4 #a1 pp4 #cad-cah1 #ceb-cei4 #d ,however1 see ,m3 pp4 #afa1 #afb1 #afh1 #cce4 ,illustration3 ,figure #a4--,,william ,,gilbert',s ,,book ,,on ,,the ,,loadstone1 ,,title ,,page ,,of ,,the ,,first ,,edition1 ,,from ,a ,,copy ,,in ,,the ,,library ,,of ,,congress4 7,photo courtesy of the ,library of ,congress47 ,there is another sense in which it is possible to contend that ,gilbert's treatise introduced modern studies in these fields4 ,he has frequently been credited with the introduction of the inductive method based upon stubborn facts1 in contrast to the methods and content of medieval ,aristotelianism4#e ,no science can be based upon faulty observations and certainly much of ,de magnete was devoted to the destruction of the fantastic tales and occult sympathies of the ,romans1 the medieval writers1 and the ,renaissance4 ,however1 let us also remember that ,gilbert added few novel empirical facts of a fundamental nature to previous observations on the loadstone4 ,gilbert's experimental work was in large part an expansion of ,petrus ,peregrinus' ,de magnete of #abfi1f and a development of works like ,robert ,norman's ,the new attractive1#g in which the author discussed how one could show experimentally the declination and inclination of a magnetized needle1 and like ,william ,borough's ,discourse on the variation of the compass or magnetized needle1#h in which the author suggested the use of magnetic declination and inclination for navigational purposes but felt too little was known about it4 ,that other sea-going nations had been considering using the properties of the magnetic compass to solve their problems of navigation in the same manner can be seen from ,simon ,stevin's ,de havenvinding4#i #e ,for example1 ,william ,whewell1 ,history of the inductive sciences1 ed4 #c1 ,new ,york1 #aheh1 vol4 #b1 pp4 #aib and #bag2 ,charles ,singer1 ,a short history of science to the nineteenth century1 ,oxford1 #aidc1 pp4 #ahh and #cdc2 and ,a4 ,r4 ,hall1 ,the scientific revolution1 ,boston1 #aief1 p4 #ahe4 #f ,petri ,peregrini maricurtenis1 de magnete1 seu rota perpetui motus1 libellus1 a reprint of the #aeeh ,angsburg edition in ,j4 ,g4 ,g4 ,hellmann1 ,rara magnetica1 ,berlin1 #ahih1 not paginated4 ,a number of editions of ,peregrinus1 work1 both ascribed to him and plagiarized from him1 appeared in the #afth century 7see ,heinz ,balmer1 ,beitrge zur ,geschichte der ,erkenntnis des ,erdmagnetismus1 ,aarau1 #aief1 pp4 #bdi-bee74 #g ,hellmann1 ibid41 ,robert ,norman1 ,the newe attractive1 containyng a short discourse of the magnes or lodestone1 and amongest other his vertues1 of a newe discovered secret and subtill propertie1 concernyng the declinyng of the needle1 touched therewith under the plaine of the horizon4 ,now first founde out by ,robert ,norman ,hydrographer4 ,london1 #aeha4 ,the possibility is present that ,norman's work was a direct stimulus to ,gilbert1 for ,wright's introduction to ,de magnete stated that ,gilbert started his study of magnetism the year following the publication of ,norman's book4 #h ,hellman1 ibid41 ,william ,borough1 ,a discourse of the variation of the compasse1 or magneticall needle4 ,wherein is mathematically shewed1 the manner of the observation1 effects1 and application thereof1 made by ,w4 ,b4 ,and is to be annexed to the newe attractive of ,r4 ,n4 ,london1 #aeif4 #i ,hellman1 ibid41 ,simon ,stevin1 ,de havenvinding1 ,leyden1 #aeii4 ,it is interesting to note that ,wright translated ,stevin's work into ,english4 ,instead of new experimental information1 ,gilbert's major contribution to natural philosophy was that revealed in the title of his book--a new philosophy of nature1 or physiology1 as he called it1 after the early ,greeks4 ,gilbert's attempt to organize the mass of empirical information and speculation that came from scholars and artisans1 from chart and instrument makers1 made him the father of the magnetic ,philosophy4#aj #aj ,as ,edward ,wright was to call him in his introduction4 ,gilbert's ,de magnete was not the first attempt to determine the nature of the loadstone and to explain how it could influence other loadstones or iron4 ,it is typical of ,greek philosophy that one of the first references we have to the loadstone is not to its properties but to the problem of how to explain these properties4 ,aristotle#aa preserved the solution of the first of the ,ionian physiologists3 ,thales too 444 seems to suppose that the soul is in a sense the cause of movement1 since he says that a stone has a soul because it causes movement to iron4 ,plato turned to a similar animistic explanation in his dialogue1 ,ion4#ab ,such an animistic solution pervaded many of the later explanations4 #aa ,aristotle1 ,on the soul1 translated by ,w4 ,s4 ,hett1 ,loeb ,classical ,library1 ,london1 #aice1 #dje;a#bj 7see also #daa;a#h3 ,some think that the soul pervades the whole universe1 whence perhaps came ,thales' view that everything is full of gods74 #ab ,plato1 ,ion1 translated by ,w4 ,r4 ,m4 ,lamb1 ,loeb ,classical ,library1 ,london1 #aibe1 #ecc 7see also #ecf74 ,that a mechanical explanation is also possible was shown by ,plato in his ,timaeus4#ac ,he argued that since a vacuum does not exist1 there must be a plenum throughout all space4 ,motion of this plenum can carry objects along with it1 and one could in this manner explain attractions like that due to amber and the loadstone4 #ac ,plato1 ,timaeus1 translated by ,r4 ,g4 ,bury1 ,loeb ,classical ,library1 ,london1 #aibi1 #hj4 ,it is difficult to determine which explanation ,plato preferred1 for in both cases the speaker may be only a foil for ,plato's opinion rather than an expression of these opinions4 ,another mechanical explanation was based upon a postulated tendency of atoms to move into a vacuum rather than upon the latter's non-existence4 ,lucretius restated this ,epicurean explanation in his ,de rerum natura4#ad ,atoms from the loadstone push away the air and tend to cause a vacuum to form outside the loadstone4 ,the structure of iron is such that it1 unlike other materials1 can be pushed into this empty space by the thronging atoms of air beyond it4 #ad ,lucretius1 ,de rerum natura1 translated by ,w4 ,h4 ,d4 ,rouse1 ,loeb ,classical ,library1 ,london1 #aibd1 bk4 ,,vi1 lines #iih-ajda4 ,galen#ae returned to a quasi-animistic solution in his denial of ,epicurus' argument1 which he stated somewhat differently from ,lucretius4 ,one can infer that ,galen held that all things have1 to a greater or lesser degree1 a sympathetic faculty of attracting its specific1 or proper1 quality to itself4#af ,the loadstone is only an inanimate example of what one finds in nutritive organs in organic beings4 #ae ,galen1 ,on the natural faculties1 translated by ,a4 ,s4 ,brock1 ,loeb ,classical ,library1 ,london1 #aiaf1 bk4 #a and bk4 #c4 ,a view similar to this appeared in ,plato1 ,timaeus1 #ha 7see footnote #ac74 #af ,this same concept was to reappear in the ,middle ,ages as the inclinatio ad simile4 ,one of the few writers whose explanations of the loadstone ,gilbert mentioned with approval is ,st4 ,thomas ,aquinas4 ,although the medieval scholastic philosophy of ,st4 ,thomas seems foreign to our way of thinking1 it formed a background to many of ,gilbert's concepts1 as well as to those of his predecessors1 and it will assist our discussion to consider briefly ,thomist philosophy and to make its terminology explicit at this point4#ag #ag ,the background for much of the following was derived from ,annaliese ,maier1 ,an der ,grenze von ,scholastik und ,naturwissenchaft1 ed #b1 ,rome1 #aieb4 ,in scholastic philosophy1 all beings and substances are a coalescence of inchoate matter and enacting form4 ,form is that which gives being to matter and which is responsible for the virtus or power to cause change1 since matter in itself is inert4 ,moreover1 forms can be grasped intellectually1 whence the nature of a being or a substance can be known4 ,any explanation of phenomena has to be based upon these innate natures1 for only if the nature of a substance is known can its properties be understood4 ,inanimate natures are determined by observation1 abstraction1 and induction1 or by classification4#ah #ah ,st4 ,thomas' epistemology for the natural inanimate world was based upon ,aristotle's dictum3 that which is in the mind was in the senses first4 ,the nature of a substance is causally prior to its properties2 while the definition of the nature is logically prior to these properties4 ,thus1 what we call the theory of a substance is expressed in its definition1 and its properties can be deduced from this definition4 ,the world of ,st4 ,thomas is not a static one1 but one of the ,aristotelian motions of quantity 7change of size71 of quality 7alteration71 and of place 7locomotion74 ,another kind of change is that of substance1 called generation and corruption1 but this is a mutation1 occurring instantly1 rather than a motion1 that requires time4 ,in mutation the essential nature is replaced by a new substantial form4 ,all these changes are motivated by a causal hierarchy that extends from the ,first ,cause1 the ,dator ,formarum1 or ,creator1 to separate intellectual substances that may be angels or demons1 to the celestial bodies that are the generantia of the substantial forms of the elements and finally to the four prime qualities 7dry and wet1 hot and cold7 of the substantial forms4 ,accidental forms are motivated by the substantial forms through the instrumentality of the four prime qualities1 which can only act by material contact4 ,the only causal agents in this hierarchy that are learned through the senses are the tangible qualities4 ,usually the prime qualities are not observed directly1 but only other qualities compounded of them4 ,one of the problems of scholastic philosophy was the incorporation1 into this system of efficient agents1 of other qualities1 such as the qualities of gravity and levity that are responsible for upward and downward motion4 ,besides the causal hierarchy of forms1 the natural world of ,st4 ,thomas existed in a substantial and spatial hierarchy4 ,all substances whether an element or a mixture of elements have a place in this hierarchy by virtue of their nature4 ,if the material were removed from its proper place1 it would tend to return4 ,in this manner is obtained the natural downward motion of earth and the natural upward motion of fire4 ,local motion can also be caused by the virtus coeli generating a new form1 or through the qualitative change of alteration4 ,since each element and mixture has its own natural place in the hierarchy of material substances1 and this place is determined by its nature1 changes of nature due to a change of the form can produce local motion4 ,if before change the substance is in its natural place1 it need not be afterwards1 and if not1 would then tend to move to its new natural place4 ,it will be noted that the scholastic explanation of inanimate motion involved the action and passion of an active external mover and a passive capacity to be moved4 ,whence the definition of motion that ,descartes#ai was later to deride1 motus est actus entis in potentia prout quod in potentia4 #ai ,ren ,descartes1 ,oeuvres1 ,charles ,adam and ,paul ,tannery1 ,paris1 #ahig-aiaj1 vol4 #b1 p4 #eig 7letter to ,mersenne1 #af ,oct41 #afci71 and vol4 #aa 7,le ,monde71 p4 #ci4 ,the original definition can be found in ,aristotle1 ,physics1 translated by ,p4 ,h4 ,wickstead and ,f4 ,m4 ,cornford1 ,loeb ,classical ,library1 ,london1 #aicd1 #bja;a#aj4 ,aquinas rephrases the definition as ,motus est actus existentis in potentia secundum quod huius modi4 ,see ,st4 ,thomas ,aquinas1 ,opera omnia1 ,antwerp1 #afab1 vol4 #b1 ,physicorum ,aristotelis expositio1 lib4 #c1 lect4 #b1 cap4 a1 p4 #bi4 ,we have seen above that the motor essentialis for terrestial change is the virtus coeli4 ,thus the enacting source of all motion and change is the heavens and the heavenly powers1 while the earth and its inhabitants becomes the focus or passive recipient of these actions4 ,in this manner the scholastic restated in philosophical terms the drama of an earth-centered universe4 ,although change or motion is normally effected through the above mentioned causal hierarchy1 it is not always necessary that actualization pass from the ,first ,cause down through each step of the hierarchy to terminate in the qualities of the individual being4 ,some of the steps could be by-passed3 for instance man's body is under the direct influence of the celestial bodies1 his intellect under that of the angels and his will under ,god4#bj ,another example of effects not produced through the tangible prime qualities is that of the tide-producing influence of the moon on the waters of the ocean or the powers of the loadstone over iron4 ,such causal relations1 where some members of the normal causal chain have been circumvented1 are called occult4#ba #bj ,st4 ,thomas ,aquinas1 op4 cit4 7footnote #ai71 vol4 #i1 ,summa contra gentiles1 lib4 #c1 cap4 #ib 7,quo modo dicitur aliquis bene fortunatus et quo modo adjuvatur homo ex superioribus causis71 p4 #cdc4 #ba ,st4 ,thomas ,aquinas1 op4 cit4 7footnote #ai71 vol4 #ag ,opuscula1 ,de operationibus occultis naturae ad queindam militem ultramontem1 pp4 #bac-bbd4 ,while ,st4 ,thomas referred to the loadstone in a number of places as something whose nature and occult properties are well known1 it was always as an example or as a tangential reference4 ,one does not find a systematic treatment of the loadstone in ,st4 ,thomas1 but there are enough references to provide a fairly explicit statement of what he considered to be the nature of the magnet4 ,in one of his earliest writings1 ,st4 ,thomas argued that the magnet attracts iron because this is a necessary consequence of its nature4#bb ,respondeo dicendum1 quod omnibus rebus naturaliter insunt quaedam principia1 quibus non solum operationes proprias efficere possunt1 sed quibus etiam eas convenientes fini suo reddant1 sive sint actiones quae consequantur rem aliquam ex natura sui generis1 sive consequantur ex natura speciei1 ut magneti competit ferri deorsum ex natura sui generis1 et attrahere ferrum ex natura speciei4 ,sicut autem in rebus agentibus ex necessitate naturae sunt principia actionum ipsae formae1 a quibus operationes proprie prodeunt convenientes fini4444 ,due to its generic form1 the loadstone is subject to natural motion of place of up and down4 ,however1 the virtus of its specific form enabled it to produce another kind of motion--it could draw iron to itself4 ,normally the virtus of a substance is limited to those contact effects that could be produced by the form operating through the active qualities of one substance1 on the relatively passive qualities of another4 ,st4 ,thomas asserted the loadstone to be one of these minerals1 the occult powers of whose form goes beyond those of the prime qualities4#bc ,forma enim elementi non habet aliquam operationem nisi quae fit per qualitates activas et passivas1 quae sunt dispositiones materiae corporalis4 ,forma autem corporis mineralis habet aliquam operationem excedentem qualitates activas et passivas1 quae consequitur speciem ex influentia corporis coelestis1 ut quod magnes attrahit ferrum1 et quod saphirus curat apostema4 ,that this occult power of the loadstone is a result of the direct influence of the virtus coeli was expounded at greater length in his treatise on the soul4#bd ,quod quidem ex propriis formarum operationibus perpendi potest4 ,formae enim elementorum1 quae sint infimae et materiae propinquissime1 non habent aliquam operationem excedentem qualitates activas et passivas1 ut rarum et densum1 et aliae huiusmodi1 qui videntur esse materiae dispositiones4 ,super has autem sunt formae mistorum quae praeter praedictas operationes1 habent aliquam operationem consequentem speciem1 quam fortiuntur ex corporibus coelestibus2 sicut quod magnes attrahit ferrum non propter calorem aut frigiis1 aut aliquid huiusmodi2 sed ex quadam participatione virtutis coelestis4 ,super has autem formas sint iterum animae plantarum1 quae habent similitudinem non solum ad ipsa corpora coelestia1 sed ad motores corporum coelestium1 inquantum sunt principia cuiusdam motus1 quibusdam seipsa moventibus4 ,super has autem ulterius sunt animae brutorum1 quae similitudinem iam habent ad substantiam moventem coelestia corpora1 non solum in operatione qua movent corpora1 sed etiam in hoc quod in seipsis cognoscitivae sunt1 licet brutorum cognitio sit materialium tantum et materialiter4444 ,st4 ,thomas placed the form of the magnet and its powers in the hierarchy of forms intermediate between the forms of the inanimate world and the forms of the organic world with its hierarchy of plant1 animal and rational souls4 ,the form of the loadstone is then superior to that of iron1 which can only act through its active and passive qualities1 but inferior to the plant soul1 that has the powers of growth from the virtus coeli4 ,this is similar to ,galen's comparison of the magnet's powers to that of the nutritive powers of organic bodies4 ,in his commentary on ,aristotle's ,physics1 ,st4 ,thomas explained how iron is moved to the magnet4 ,it is moved by some quality imparted to the iron by the magnet4#be ,illud ergo trahere dicitur1 quod movet alterum ad seipsum4 ,movere autem aliquid secundum locum ad seipsum contingit tripliciter4 ,uno modo sicut finis movet2 unde et finis dicitur trahere1 secundum illud poetate3 trahit sua quemque voluptas3 et hoc modo potest dici quod locus trahit id1 quod naturaliter movetur ad locum4 ,alio modo potest dici aliquid trahere1 quia movet illud ad seipsum alterando aliqualiter1 ex qua alteratione contingit quod alteratum moveatur secundum locum3 et hoc modo magnes dicitur trahere ferrum4 ,sicut enim generans movet gravia et levia1 inquantum dat eis formarum per quam moventur ad locum1 ita et magnes dat aliquam qualitatem ferro1 per quam movetur ad ipsum4 ,et quod hoc sit verum patet ex tribus4 ,primo quidem quia magnes non trahit ferrum ex quacumque distantia1 sed ex propinquo2 si autem ferrum moveretur ad magnetem solum sicut ad finem1 sicut grave ad suum locum1 ex qualibet distantia tenderet ad ipsum4 ,secundo1 quia1 si magnes aliis perungatur1 ferrum attrahere non potest2 quasi aliis vim alterativam ipsius impedientibus1 aut etiam in contrarium alterantibus4 ,tertio1 quia ad hoc quod magnes attrahat ferrum1 oportet prius ferrum liniri cum magnete1 maxime si magnes sit parvus2 quasi ex magnete aliquam virtutem ferrum accipiat ut ad eum moveatur4 ,sic igitur magnes attrahit ferrum non solum sicut finis1 sed etiam sicut movens et alterans4 ,tertio modo dicitur aliquid attrahere1 quia movet ad seipsum motu locali tantum4 ,et sic definitur hic tractio1 prout unum corpus trahit alteram1 ita quod trahens simul moveatur cum eo quod trahitur4 ,as the generans of terrestrial change moves what is light and heavy to another place by implanting a new form in a substance1 so the magnet moves the iron by impressing upon it the quality by which it is moved4 ,by virtue of the new quality1 the iron is not in its natural place and moves accordingly4 ,st4 ,thomas proved that the loadstone acts as a secondary generans in three ways3 7#a7 the loadstone produces an effect not from any distance but only from a nearby position 7showing that this motion is due to more than place alone71 7#b7 rubbing the loadstone with garlic acts as if it impedes or alters the virtus magnetis1 and 7#c7 the iron must be properly aligned with respect to the loadstone in order to be moved1 especially if the loadstone is small4 ,thus the iron is moved by the magnet not only to a place1 but also by changing and altering it3 one has not only the change of locomotion but that of alteration4 ,moreover the source of this alteration in the iron is not the heavens but the loadstone4 ,accordingly the loadstone could cause change in another substance because it could influence the nature of the other substance4 #bb ,st4 ,thomas ,aquinas1 op4 cit4 7footnote #ai71 vol #g1 ,scriptum in quartum librum sententiarum magistri ,petri ,lombardi1 lib4 #d1 disq4 #cc 7,de diversis coniugii legibus71 art4 #a 7,utrum habere plures uxores sit contra legem naturae71 p4 #afh4 ,the same statement occurs in one of his most mature works1 op4 cit4 vol4 #bj1 ,summa theologica1 pars #c 7supplementum71 quaestio #fe 7,de pluralitate uxorum in quinque articulos divisa71 art4 #a 7,utrum habere plures uxores sit contra legem naturae71 p4 #ajg4 #bc ,st4 ,thomas ,aquinas1 op4 cit4 7footnote #ai71 vol4 #h1 ,quaestio unica3 de spiritualibus creaturis1 art4 #b 7,utrum substantia spiritualis possit uniri corpori71 p4 #djd4 ,see also vol4 #i1 ,summa contra gentiles1 lib4 #c1 cap4 #ib 7,quomodo dicitur aliquis bene fortunatus1 et quomodo adjuvatur homo ex superioribus causis71 p4 #cdd2 and vol4 #ag1 ,opuscula1 ,de operationibus occultis naturae ad queindam militem ultramontem1 pp4 #bac-bad4 #bd ,st4 ,thomas ,aquinas1 op4 cit4 7footnote #ai71 vol4 #h1 ,quaestio unica3 de anima1 art4 #a 7,utrum anima humana possit esse forma et hoc aliquid71 p4 #dcg4 ,see also vol4 #h1 ,quaestio3 ,de veritate1 quaestio #e 7,de providentia71 art4 #aj 7,utrum humani actus a divina providentia gubernentur mediis corporibus coelestibus71 p4 #fgh4 #be ,st4 ,thomas ,aquinas1 op4 cit4 7footnote #ai71 vol4 #b1 ,physicorum ,aristotelis expositio1 lib4 #g1 lect4 #c1 cap4 g 7,probatur in motu locali quod movens et motum oportet esse simul71 p4 #ig 7quoted in ,gilbert1 ,m3 p4 #ajd74 ,about the time that ,st4 ,thomas was writing his letter ,de operationibus occultis naturae to a certain knight1 ,petrus ,peregrinus was writing from a military camp a letter in which he showed how certain relatively new effects could be produced by the loadstone4 ,he was more interested in what he could do with the magnet than in explaining these effects4 ,however1 he discussed it at sufficient length for one to find that his explanation of magnetic phenomena was basically similar to that of his contemporary1 ,st4 ,thomas4 ,peregrinus based his discussion of the loadstone upon its nature and analyzed magnetic phenomena in terms of the change of alteration4 ,in magnetic attraction1 the nature of the iron is altered by having a new quality impressed upon it1#bf and the loadstone is the agent that makes the iron the same species as the stone4#bg 444 ,oportet enim quod illud quod iam conversum est ex duobus in unum1 sit in eadem specie cum agente2 quod non esset1 si natura istud impossible eligeret4 ,this impressed similarity to the agent1 ,peregrinus realized1 is not a pole of the same polarity but one opposite to that of the inducing pole4 ,to produce this effect1 the virtue of the stronger agent dominates the weaker patient and impresses the virtue of the stronger on the weaker so that they are made similar4#bh 444 ,in cuius attractione1 lapis fortioris virtutis agens est2 debilioris vero patiens4 ,a further instance of alteration occurs in the reversal of polarity of magnetized iron when one brings two similar poles together4 ,again1 the stronger agent dominates the weaker patient and the iron is left with a similarity to the last agent4#bi 444 ,causa huis est impressio ultimi agentis1 confundentis et alterantis virtutem primi4 ,in this assimilation of the agent to the patient1 another effect is produced3 the agent not only desires to assimilate the patient to itself1 but to unite with it to become one and the same4 ,speaking of the motion to come together1 he says3#cj ,huius autem rei causam per hanc viam fieri existimo3 agens enim intendit suum patiens non solum sibi assimilare1 sed unire1 ut ex agente et patiente fiat unum1 per numerum4 ,et hoc potes experiri in isto lapide mirabili in hunc modum4444 ,agens ergo1 ut vides experimento1 intendit suum paciens sibi unire2 hoc autem fit ratione similitudinis inter ea4 ,oportet ergo 444 virtute attractionis1 fiat una linea1 ex agente et patiente1 secundum hunc ordinem 444 ,the nature of the magnet1 as an active cause1 tends to enact1 and since it acts in the best manner in which it is able1 it acts so as to preserve the similarities of opposite poles4#ca ,natura autem1 que tendet ad esse1 agit meliori modo quo potest1 eligit primum ordinem actionis1 in quo melius salvatur idemptitas1 quam in secundo 444 ,thus unlike poles tend to come together when a dissected magnet is reassembled4 ,like ,st4 ,thomas1 ,peregrinus argued that the magnet receives its powers from the heavens4 ,but he further specified this by declaring that different virtues from the different parts of the heavens flow into their counterpart in the loadstone--from the poles of the heavens the virtue flows into the poles of the magnet1#cb ,praeterea cum ferrum1 vel lapis1 vertatur tarn ad partem meridionalem quam ad partem septemtrionalem 444 existima cogimur1 non solum a partem septemtrionali1 verum etiam a meridionali virtutem influi in polos lapidis1 magis quam a locis minere 444 ,omnes autem orbes meridiani in polis mundi concurrent2 quare1 a polis mundi1 poli magnetis virtutem recipiunt4 ,et ex hoc apparet manifeste quod non ad stellam nauticam movetur1 cum ibi non concurrant orbes meridiani1 sed in polis2 stella enim nautica1 extra orbem meridianum cuiuslibet regionis semper invenitur1 nisi bis1 in completa firmanenti revolutione4 ,ex hiis ergo manifestum est quod a partibus celi1 partes magnetis virtutem recipiunt4 and similarly for the other parts of the heavens and the other parts of the loadstone4#cc ,ceteras autem partes lapidis merito estimare potes1 influentiam a reliquis celi partibus retinere1 ut non sic solum polos lapidis a polis mundi1 sed totum lapidem a toto celo1 recipere influentiam et virtutem1 estimes4 ,physical proof for such influences was adduced by ,peregrinus from the motions of the loadstone4 ,that the poles of the loadstone receive their virtue from the poles of the heavens follows experimentally from north-south alignment of a loadstone4 ,that not only the poles but the entire loadstone receives power from corresponding portions of the heavens follows from the fact that a spherical loadstone1 when properly balanced1 would follow the motion of the heavens4#cd ,quod tibi tali modo consulo experire3 444 ,et si tunc lapis moveatur secundum celi motum1 gaudeas te esse assecutum secretum mirabile2 si vero non1 imperitie tue1 potiusquam nature1 defectus imputetur4 ,in hoc autem situ1 seu modo positionis1 virtutes lapidis huius estimo conservari proprie1 et in reliquis sitibus celi virtutem eius obsecari1 seu ebetari1 potiusquam conservari puto4 ,per hoc autem instrumentum excusaberis ab omni horologio2 nam per ipsum scire poteris ,ascensus in quacumque hora volueris1 et omnes alias celi dispositiones1 quas querunt ,astrologi4 ,as the heavens move eternally1 so the spherical loadstone must be a perpetuum mobile4 ,another of the scholars whose explanation of the loadstone ,gilbert noted with approval was ,cardinal ,nicholas of ,cusa4#ce ,the latter's references to it were not as direct as those of ,st4 ,thomas1 but he did use it as an image several times to provide a microcosmic example of the relation of ,god to his creation4 ,from this one can infer that he explained the preternatural motion of the magnet and the iron by impressed qualities1 the heavens being the agent for the loadstone1 and the loadstone1 the agent for iron4 #bf ,hellmann1 op4 cit4 7footnote #f71 ,peregrinus1 pt4 #a1 ch4 #h4 ,the magnet attracts the iron secundum naturalem appetitum lapidis 444 sine resistentia4 ,there is no natural resistence to this motion since it is no longer contrary to the nature of the iron4 ,the nature of the iron has changed4 #bg ,ibid41 pt4 #a1 ch4 #i4 #bh ,ibid41 pt4 #a1 ch4 #i4 #bi ,ibid41 pt4 #a1 ch4 #h4 #cj ,ibid41 pt4 #a1 ch4 #i4 #ca ,ibid41 pt4 #a1 ch4 #i4 ,see also footnote #bg4 #cb ,ibid41 pt4 #a1 ch4 #aj4 ,see also ch4 #d4 #cc ,ibid41 pt4 #a1 ch4 #aj4 ,see also ch4 #d4 #cd ,ibid41 pt4 #a1 ch4 #aj4 #ce ,however1 he may not always have approved of him4 ,see ,m3#gd2 ,overinquisitive theologians1 too1 seek to light up ,god's mysteries and things beyond man's understanding by means of the loadstone and amber4 ,in the ,idiota de sapientia the ,cardinal used the image of the magnet and the iron to provide a concrete instance of his coincidentia oppositorum1 to illustrate how eternal wisdom1 in the ,neoplatonic sense1 could1 at the same time1 be principle or cause of being1 its complement and also its goal4#cf ,si igitur in omni desiderio vitae intellectualis attenderes1 a quo est intellectus1 per quod movetur et ad quod1 in te comperires dulcedinem sapientiae aeternae illam esse1 quae tibi facit desiderium tuum ita dulce et delectabile1 ut in inerrabili affectu feraris ad eius comprehensionem tanquam ad immortalitatem vitae tue1 quasi ad ferrum et magnetem attendas4 ,habet enim ferrum in magnete quoddam sui effluxus principium2 et dum magnes per sui praesentiam excitat ferrum grave et ponderosum1 ferrum mirabili desiderio fertur etiam supra motum naturae1 quo secundum gravitatem deorsum tendere debet1 et sursum movetur se in suo principio uniendo4 ,nisi enim in ferro esset quaedam praegustatio naturalis ipsius magnetis1 non moveretur plus ad magnetem quam ad alium lapidem2 et nisi in lapide esset major inclinatio ad ferrum quam cuprum1 non esset illa attractio4 ,habet igitur spiritus noster intellectualis ab aeterna sapientia principium sic intellectualiter essendi1 quod esse est conformius sapientae quam aliud non intellectuale4 ,hinc irraditio seu immissio in sanctam animam est motus desideriosus in excitatione4 ,by virtue of the principle that flows from the magnet to the iron--which principle is potentially in the iron1 for the iron already has a foretaste for it--the excited iron could transcend its gravid nature and be preternaturally moved to unite with its principle4 ,reciprocally1 the loadstone has a greater attraction to the iron than to other things4 ,just as the power of attraction comes from the loadstone1 so the ,deity is the source of our life4 ,just as the principle implanted in the magnet moves the iron against its heavy nature1 so the ,deity raises us above our brutish nature so that we may fulfill our life4 ,as the iron moves to the loadstone1 so we move to the ,deity as to the goal and end of our life4 ,in ,de pace fidei1 ,cusa#cg again used the iron and magnet as an example of motion contrary to and transcending nature4 ,he explained this supernatural motion as being due to the similarity between the nature of the iron and the magnet1 and this in turn is analogous to the similarity between human spiritual nature and divine spiritual nature4 ,as the iron can move upward to the loadstone because both have similar natures1 so man can transcend his own nature and move towards ,god when his potential similitude to ,god is realized4 ,another image used by ,cusa was the comparison of ,christ to the magnetic needle that takes its power from the heavens and shows man his way4#ch #cf ,nicholas of ,cusa 7,nicolaus ,cusaneus71 ,nicolaus von ,cues1 ,texte seiner philosophischen ,schriften1 ed4 ,a4 ,petzelt1 ,stuttgart1 #aidi1 bk4 #a1 ,idiota de sapientia1 p4 #cjf 7quoted in ,gilbert1 ,m3#ajd74 ,it is interesting that ,cusa held that the loadstone has an inclination to iron1 as well as the converse6 #cg ,cusa1 ,cusa ,schriften1 vol4 #h1 ,de pace fidei1 translated by ,l4 ,mohler1 ,leipzig1 #aidc1 ch4 #ab1 p4 #abg4 #ch ,cusa1 ,exercitationes1 ch4 #g1 #efc and #eff1 quoted in1 ,f4 ,a4 ,scharpff1 ,des ,cardinals und ,bischofs ,nicolaus ,von ,cusa ,wichtigste ,schriften in ,deutscher ,uebersetzung1 ,freiburg1 #ahfb1 p4 #dce4 ,see also ,martin ,billinger1 ,das ,philosophische in ,den ,excitationen ,des ,nicolaus ,von ,cues1 ,heidelberg1 #aich1 and ,cusa ,schriften 7see footnote #cg71 vol4 #h1 p4 #bji1 note #aje4 ,gilbert 7,m3 p4 #bbc7 called the compass the finger of ,god4 ,the ,elizabethan ,englishman ,robert ,norman also turned to the ,deity to explain the wonderful effects of the loadstone4#ci ,now therefore 444 divers have whetted their wits1 yea1 and dulled them1 as ,i have mine1 and yet in the end have been constrained to fly to the cornerstone3 ,i mean ,god3 who 444 hath given ,virtue and power to this ,stone 444 to show one certain point1 by his own nature and appetite 444 and by the same vertue1 the ,needle is turned upon his own ,center1 ,i mean the ,center of his ,circular and invisible ,vertue 444 ,and surely ,i am of opinion1 that if this would be found in a ,sphericall form1 extending round about the ,stone in ,great ,compass1 and the dead body ,stone in the middle therof3 ,whose center is the center of his aforesaid ,vertue4 ,and this ,i have partly proved1 and made visible to be seen in the same manner1 and ,god sparing me life1 ,i will herein make further ,experience4 ,again1 one can infer that the heavens impart a guiding principle to the iron which acts under the influence of this ,superior ,cause4 ,one of the points made in ,st4 ,thomas' argument on motion due to the loadstone was that there is a limit to the virtus of the loadstone1 but he did not specify the nature of it4 ,norman refined the ,thomist concept of a bound by making it spherical in form1 foreshadowing ,gilbert's orbis virtutis4 ,gilbert's philosophy of nature does not move far from scholastic philosophy1 except away from it in logical consistency4 ,as the concern of ,aristotle and of ,st4 ,thomas was to understand being and change by determining the nature of things1 so ,gilbert sought to write a logos of the physis1 or nature1 of the loadstone--a physiology4#dj ,this physiology was not formally arranged into definitions obtained by induction from experience1 but nevertheless there was the same search for the quiddity of the loadstone4 ,once one knew this nature then all the properties of the loadstone could be understood4 #ci ,hellmann1 op4 cit4 7footnote #f71 ,norman1 bk4 #a1 ch4 #h4 #dj ,m3 p4 #ad4 ,gilbert described the nature of the loadstone in the terms of being that were current with his scholarly contemporaries4 ,this was the same ontology that scholasticism had taught for centuries--the doctrine of form and matter that we have already found in ,st4 ,thomas and ,nicholas of ,cusa4 ,thus we find ,richard ,hooker#da remarking that form gives being and that form in other creatures is a thing proportionable unto the soul in living creatures4 ,francis ,bacon1#db in speaking of the relations between causes and the kinds of philosophy1 said3 ,physics is the science that deals with efficient and material causes while ,metaphysics deals with formal and final causes4 ,john ,donne#dc expressed the problem of scholastic philosophy succinctly3 ,this twilight of two yeares1 not past or next1 ,some embleme is of me1 444 444 of stuffe and forme perplext1 ,whose what and where1 in disputation is 444 ,as we shall see1 ,gilbert continued in the same tradition1 but his interpretation of form and formal cause was much more anthropomorphic than that of his predecessors4 ,gilbert began his ,de magnete by expounding the natural history of that portion of the earth with which we are familiar4#dd ,having declared the origin and nature of the loadstone1 we hold it needful first to give the history of iron also 444 before we come to the explication of difficulties connected with the loadstone 444 we shall better understand what iron is when we shall have developed 444 what are the causes and the matter of metals 444 ,his treatment of the origin of minerals and rocks agreed in the main with that of ,aristotle1#de but he departed somewhat from the peripatetic doctrine of the four elements of fire1 air1 water1 and earth4#df ,instead1 he replaced them by a pair of elements4#dg 7,if the rejection of the four ,aristotelian elements were clearer1 one might consider this a part of his rejection of the geocentric universe but he did not define his position sufficiently47#dh #da ,richard ,hooker4 ,of the laws of ecclesiastical polity1 bk4 #a1 ch4 #c1 sect4 #d 7,works1 ,oxford1 ,clarendon ,press1 #ahfe1 vol4 #a1 p4 #aeg7 #db ,francis ,bacon1 ,de augmentis scientiarum1 bk4 #c1 ch4 #d1 in ,works1 ed4 ,j4 ,spedding1 ,r4 ,l4 ,ellis1 and ,d4 ,d4 ,heath1 ,boston1 n4d4 7#aijj871 vol4 #b1 p4 #bfg4 #dc ,the poems of ,john ,donne1 ed4 ,h4 ,j4 ,c4 ,grierson1 ,london1 ,oxford ,university ,press1 #aicc1 p4 #age 7,to the ,countesse of ,bedford1 ,on ,new ,yeares ,day74 #dd ,m3 pp4 #cc1 #cd4 #de ,m3 pp4 #cd1 #ce4 ,aristotle1 ,works1 ed4 ,w4 ,d4 ,ross1 ,oxford1 #aijh--aieb1 vol4 #b1 ,de generatione et corruptione1 translated by ,h4 ,h4 ,joachim1 #aicj1 vol4 #c1 ,meteorologica1 translated by ,e4 ,w4 ,webster1 #aica4 #df ,m3 pp4 #cd1 #ce1 #fd1 #fe1 #fi1 #ha4 ,dr4 ,h4 ,guerlac has kindly brought to my attention the similarity between the explanation given in ,gilbert and that given in the ,meteorologica1 bk4 #c1 ch4 #f4 p4 #cgh4 #dg ,m3 p4 #hc4 #dh ,a statement of the relation between ,aristotle's four elements and place can be found in ,maier1 op4 cit4 7footnote #ag71 pp4 #adc-ahb4 ,according to ,gilbert the primary source of matter is the interior of the earth1 where exhalations and spiritus arise from the bowels of the earth and condense in the earth's veins4#di ,if the condensations1 or humors1 are homogeneous1 they constitute the materia prima of metals4#ej ,from this materia prima1 various metals may be produced1#ea according to the particular humor and the specificating nature of the place of condensation4#eb ,the purest condensation is iron3 ,in iron is earth in its true and genuine nature4#ec ,in other metals1 we have instead of earth1 condensed and fixed salts1 which are efflorescences of the earth4#ed ,if the condensed exhalation is mixed in the vein with foreign earths already present1 it forms ores that must be smelted to free the original metal from dross by fire4#ee ,if these exhalations should happen to pass into the open air1 instead of being condensed in the earth1 they may return to the earth in a 7meteoric7 shower of iron4#ef #di ,m3 pp4 #ba1 #cd1 #ce1 #cf1 #de4 #ej ,m3 pp4 #ce1 #cf1 #ch1 #fi2 see1 however1 pp4 #db-dc3 ,iron ore1 therefore1 as also manufactured iron1 is a metal slightly different from the homogenic telluric body because of the metallic humor it has imbibed 444 #ea ,m3 pp4 #ai1 #cd1 #cf1 #cg1 #db1 #fi4 #eb ,m3 pp4 #ce1 #cf1 #cg1 #ch4 #ec ,m3 pp4 #ch1 #fc1 #fi1 #hd2 on p4 #cd he says that iron is more truly the child of the earth than any other metal2 it is the hardest because of the strong concretion of the more earthy substance4 #ed ,m3 pp4 #ba1 #ce1 #cg1 #ch4 #ee ,m3 pp4 #ce1 #fc4 #ef ,m3 pp4 #de1 #df4 ,gilbert was indeed writing a new physiology1 both in the ancient sense of the word and the modern4 ,the process of the formation of metals had many biological overtones1 for it was a kind of metallic epigenesis4#eg ,within the globe are hidden the principles of metals and stones1 as at the earth's surface are hidden the principles of herbs and plants4#eh ,in all cases1 the spiritus acts as semen and blood that inform and feed the proper womb in the generation of animals4#ei ,the brother uterine of iron1#fj the loadstone1 is formed in this manner4 ,as the embryo of a certain species is the result of the specificating nature of the womb in which the generic seed has been placed1 so the kind of metal is the result of a certain humor condensing in a particular vein in the body of the earth4 #eg ,gilbert's terminology strongly suggests that he was familiar with alchemical literature1 as well as that of medical chemistry4 ,he has been credited as being highly skilled in chemistry4 ,see ,sir ,walter ,langdon-,brown1 ,william ,gilbert3 his place in the medical world1 ,nature1 vol4 #aed1 pp4 #acf-aci1 #aidd4 #eh ,ibid41 p4 #cg4 #ei ,m3 pp4 #ce1 #cf1 #ec1 #ei4 ,see also ,galen1 op4 cit4 7footnote #ae7 bk4 #b1 ch4 #c4 #fj ,m3 pp4 #af1 #ei4 ,gilbert developed this biological analogy further by ascribing to metals a process of decay after reaching maturity4 ,once these solid materials have been formed1 they will degenerate unless protected1 forming earths of various kinds as a result4#fa ,the rind of the earth#fb is produced by this process of growth and decay4 ,if these earths are soaked with humors1 transparent materials are formed4#fc #fa ,m3 pp4 #bj1 #ba1 #cb1 #fa1 #fc1 #ff1 #gj4 #fb ,m3 p4 #ei4 #fc ,m3 p4 #hd4 ,as we shall see below1 the ultimate cause of this internal and superficial life is the motion of the earth1 which animation is the expression of the magnetic soul of this sphere4#fd ,as the life of animals results from the constant working of the heart and arteries1#fe so the daily motion of the earth results in a constant generation of mineral life within the earth4 ,in contrast to ,aristotle's#ff making the motion of the heavens the cause of continuous change1 ,gilbert made that of the earth the remote cause4#fg ,however1 unlike the constant cyclical transmutation of substances in ,aristotle1 there is only generation and decay4 #fd ,m3 pp4 #caj1 #caa1 #cab4 #fe ,m3 p4 #cch4 ,a somewhat different opinion1 although not necessarily inconsistent is expressed on p4 #ff1 where he says the surface is due to the action of the atmosphere1 the waters1 and the radiations and other influences of heavenly bodies4 #ff ,aristotle1 op4 cit4 7footnote #de71 ,de generatione et corruptione1 bk4 #b1 ch4 #aj4 #fg ,m3 pp4 #caa1 #ccd1 #cch4 ,gilbert made a number of successive generalizations in order to arrive at the induction that the form of the loadstone is a microcosmic anima of that of the earth4#fh ,after comparing the properties of the loadstone and of iron1 his first step in this induction was that the two materials1 found everywhere1#fi are consanguineous3#gj ,these two associated bodies possess the true1 strict form of one species1 though because of the outwardly different aspect and the inequality of the selfsame innate potency1 they have hitherto been held to be different 444 ,good iron and good loadstone are more similar than a good and a poor loadstone1 or a good and a poor iron ore4#ga ,moreover1 they have the same potency1#gb for the innate potency of one can be passed to the other3#gc ,the stronger invigorates the weaker1 not as if it imparted of its own substances or parted with aught of its own strength1 nor as if it injected into the other any physical substance2 but rather the dormant power of the one is awakened by the other's without expenditure4 ,in addition1 the potency can be passed only to the other4#gd ,finally they both have the same history3 ,we see both the finest magnet and iron ore visited as it were by the same ills and diseases1 acting in the same way and with the same indications1 preserved by the same remedies and protective measures1 and so retaining their properties 444 they are both impaired by the action of acrid liquids as though by poison#ge 444 each is saved from impairment by being kept in the scrapings of the other4 ,so 444 form1 essence and appearance are one4#gf ,any difference between the loadstone proper and the iron proper is due to a difference in the actual power of the magnetic virtue3#gg ,weak loadstones are those disfigured with dross metallic humors and with foreign earth admixtures1 hence one may conclude they are further removed from the mother earth and are more degenerate4 #fh ,m3 pp4 xlvii1 #cji1 #cbh4 #fi ,m3 pp4 #ah1 #bj1 #dd1 #df1 #fi4 #gj ,m3 pp4 #ei1 #fa1 #fc4 #ga ,m3 pp4 #fj1 #fc4 #gb ,m3 p4 #aaj4 #gc ,m3 pp4 #fj1 #fa4 #gd ,m3 p4 #fb4 #ge ,m3 p4 #fc4 #gf ,m3 p4 #fj4 #gg ,m3 pp4 #ai1 #ba1 #dc1 #ec1 #fa1 #fc1 #ahd4 ,gilbert's second induction was that they are true and intimate parts of the globe1#gh that is1 that they are piece of the materia prima of all we see about us4 ,for they seem to contain within themselves the potency of the earth's core and of its inmost viscera4#gi ,whence1 in ,gilbert's philosophy1 the earthy matter of the elements was not passive or inert#hj as it was in ,aristotle's1 but already had the magnetic powers of loadstone4 ,being endowed with properties1 it was1 in peripatetic terms1 a simple body4 #gh ,m3 p4 #fa4 #gi ,m3 pp4 #ff1 #fg4 #hj ,m3 p4 #fi4 ,gilbert is confusing ,aristotelian matter and an element4 ,he includes cold and dry1 with formless and inert6 ,see also ,maier1 op4 cit4 7footnote #ag74 ,if these pieces of earth proper1 before decay1 are loadstones1 then one may pass to the next induction that the earth itself is a loadstone4#ha ,conversely1 a terrella has all the properties of the earth3#hb ,every separate fragment of the earth exhibits in indubitable experiments the whole impetus of magnetic matter2 in its various movements it follows the terrestial globe and the common principle of motion4#hc #ha ,m3 p4 #fc2 bk4 #a1 ch4 #ag4 #hb ,m3 pp4 #fg1 #aha-ahc1 #bce-bdj1 #bha-bhi1 #cac-cad4 #hc ,m3 p4 #ga4 ,see also pp4 #cad and #cca4 ,it is not clear1 at this point1 whether he believed a properly balanced terrella would be a perpetuum mobile4 ,the next induction that ,gilbert made was that as the magnet possesses verticity and turns towards the poles1 so the loadstone-earth possesses a verticity and turns on an axis fixed in direction4#hd ,he could now discuss the motions of a loadstone in general1 in terms of its nature1 just as an ,aristotelian discussed the motion of the elements in terms of their nature4 #hd ,m3 pp4 #fh1 #gj-ga1 #ig1 #abi1 #agi-ahj1 #caa1 #cae1 #cag-cce ,gilbert implied 7,m3 p4 #aff71 that a terrella does not rotate as ,peregrinus said1 due to resistance 7,m3 p4 #cbf71 or due to the mutual nature of coition 7,m3 p4 #aff72 or even to the rotation of the earth 7,m3 p4 #ccb74 ,however 7,m3 p4 #abi71 he also mentioned that a terrella would revolve by itself6 ,but before reaching this point in his argument1 ,gilbert digressed to classify the different kinds of attractions and motions which the elements produce4 ,in particular1 he distinguished electric attraction from magnetic coition1 and pointed out the main features of electrical attraction4 ,since the resultant motions were different1 the essential natures of electric and magnetic substances had to differ4 ,gilbert introduced his treatment of motion by discussing the attraction of amber4 ,all sufficiently light solids#he and even liquids1#hf but not flame or air#hg are attracted by rubbed amber4 ,heat from friction1#hh but not from alien sources like the sun#hi or the flame1#ij produce this affection4 ,by the use of a detector modeled after the magnetic needle1 which we would call an electroscope but which he called a versorium1#ia ,gilbert was able to extend the list of substances that attract like amber4#ib ,these ,gilbert called electricae4#ic #he ,m3 pp4 #gh1 #hb1 #hd1 #hf4 #hf ,m3 pp4 #gh1 #hi1 #ia4 #hg ,m3 pp4 #hi1 #ie4 #hh ,m3 pp4 #hc1 #hf4 #hi ,m3 pp4 #ha1 #hf1 #hg4 #ij ,m3 pp4 #hj1 #ha1 #hf1 #hg4 #ia ,m3 p4 #gi4 #ib ,m3 pp4 #gg-gh1 #gi4 #ic ,m3 p4 #gh4 ,the definition ,gilbert gave of an electric in the glossary at the beginning of his treatise was not an experimental one3 ,electricae1 quae attrahunt eadem ratione ut electrum4 ,possibly as a result of testing experimentally statements like that of ,st4 ,thomas1 on the effect of garlic on a loadstone1 ,gilbert discovered that the interposition of even the slightest material 7except a fluid like olive oil7 would screen the attraction of electrics4#id ,hence the attraction is due to a material cause1 and1 since it is invisible1 it is due to an effluvium4#ie ,it must be much rarer than air1#if for if its density were that of air or greater1 it would repel rather than attract4#ig #id ,m3 pp4 #hf1 #ia1 #ace4 #ie ,m3 pp4 #if1 #ace4 #if ,m3 p4 #hi4 #ig ,m3 pp4 #ij1 #ib1 #ie4 ,the source of the effluvia could be inferred from the properties of the electrics4 ,many but not all of the electrics are transparent1 but all are firm and can be polished4#ih ,since they retain the appearance and properties of a fluid in a firm solid mass1#ii ,gilbert concluded that they derived their growth mostly from humors or were concretions of humors4#ajj ,by friction1 these humors are released and produce electrical attraction4#aja #ih ,m3 pp4 #hc1 #hd1 #he4 #ii ,m3 p4 #hd4 #ajj ,m3 pp4 #hd1 #hi4 ,see also ,aristotle1 op4 cit4 7footnote #de71 ,meteorologica1 bk4 #d4 #aja ,m3 p4 #ij4 ,this humoric source of the effluvia was substantiated by ,gilbert in a number of ways4 ,electrics lose their power of electrical attraction upon being heated1 and this is because the humor has been driven off4#ajb ,bodies that are about equally constituted of earth and humor1 or that are mostly earth1 have been degraded and do not show electrical attraction4#ajc ,bodies like pearls and metals1 since they are shiny and so must be made of humors1 must also emit an effluvium upon being rubbed1 but it is a thick and vaporous one without any attractive powers4#ajd ,damp weather and moist air can weaken or even prevent electrical attraction1 for it impedes the efflux of the humor at the source and accordingly diminishes the attraction4#aje ,charged bodies retain their powers longer in the sun than in the shade1 for in the shade the effluvia are condensed more1 and so obscure emission4#ajf #ajb ,m3 pp4 #hd1 #he4 #ajc ,m3 p4 #hd4 #ajd ,m3 p4 #ij4 ,see also p4 #ie4 #aje ,m3 pp4 #gh1 #he-hf1 #ia4 7see particularly the heated amber experiment described on p4 #hf74 #ajf ,m3 p4 #hg4 ,all these examples seemed to justify the hypothesis that the nature of electrics is such that material effluvia are emitted when electrics are rubbed1 and that the effluvia are rarer than air4 ,gilbert realized that as yet he had not explained electrical attraction1 only that the pull can be screened4 ,the pull must be explained by contact forces1#ajg as ,aristotle#ajh and ,aquinas#aji had argued4 ,accordingly1 he declared1 the effluvia1 or spiritus1#aaj emitted take hold of the bodies with which they unite1 enfold them1 as it were1 in their arms1 and bring them into union with the electrics4#aaa #ajg ,m3 p4 #ib4 #ajh ,aristotle1 ,physics1 translated by ,p4 ,h4 ,wicksteed and ,f4 ,m4 ,cornford1 ,loeb ,classical ,library1 ,london1 #aicd1 bk4 #g1 ch4 #a1 #bdb;b#be4 #aji ,st4 ,thomas ,aquinas1 op4 cit4 7footnote #ai71 vol4 #b1 ,physicorum ,aristotelis expositio1 lib4 #g1 lect4 #b 7,in moventibus et motis non potest procedi in infinitum1 sed oportet devenire ad aliquid primum movens immobile71 cap4 d1 p4 #if4 #aaj ,m3 p4 #id4 #aaa ,m3 p4 #ie4 ,it can be seen how this uniting action is effected if objects floating on water are considered1 for solids can be drawn to solids through the medium of a fluid4#aab ,a wet body touching another wet body not only attracts it1 but moves it if the other body is small1#aac while wet bodies on the surface of the water attract other wet bodies4 ,a wet object on the surface of the water seeks union with another wet object when the surface of the water rises between both3 at once1 like drops of water1 or bubbles on water1 they come together4#aad ,on the other hand1 a dry body does not move toward a wet1 nor a wet to a dry1 but rather they seem to go away from one another4#aae ,moreover1 a dry body does not move to the dry rim of the vessel while a wet one runs to a wet rim4#aaf #aab ,m3 p4 #ic4 #aac ,m3 pp4 #ib1 #ic4 #aad ,m3 p4 #ic4 #aae ,m3 p4 #id4 #aaf ,m3 p4 #id4 ,by means of the properties of such a fluid1 ,gilbert could explain the unordered coming-together that he called coacervation4#aag ,different bodies have different effluvia1 and so one has coacervation of different materials4 ,thus1 in ,gilbert's philosophy air was the earth's effluvium and was responsible for the unordered motion of objects towards the earth4#aah #aag ,m3 p4 #ig4 #aah ,m3 p4 #ib 7see also p4 #cci74 ,although ,gilbert does not make it explicit1 this would solve the medieval problem of gravitation without resorting to a ,ptolemaic universe4 ,in addition1 since coacervation is electric1 and electric forces can be screened1 it should have been possible to reduce the downward motion of a body by screening6 ,the analogy between electric attraction and fluids is a most concrete one1 yet lying beneath this image is a hypothesis that is difficult to fix into a mechanical system based upon contact forces4 ,this is the assumption that under the proper conditions bodies tend to move together in order to participate in a more complete unity4#aai ,the steps in electrical attraction were described as occurring on two different levels of abstraction3 first one has physical contact through an effluvium or spiritus that connects the two objects physically4 ,then1 as a result of this contact1 the objects somehow sense#abj that a more intimate harmony is possible1 and move accordingly4 ,gilbert called the motion that followed contact1 attraction4 ,however1 this motion did not connote what we would call a force3#aba it did not correspond directly to a push or pull1 but it followed from what one might term the apprehension of the possibility of a more complete participation in a formal unity4 ,the physical unity due to the spiritus was the prelude to a formal organic unity1 so that humor is rerum omnium unitore4 ,gilbert's position can be best seen in the following3#abb ,spiritus igitur egrediens ex corpora1 quod ab humore aut succo aqueo concreverat1 corpus attrahendum attingit1 attactum attrahenti unitur2 corpus peculiari effluviorum radio continguum1 unum effecit ex duobus3 unita confluunt in conjunctissimam convenientiam1 quae attractio vulgo dicitur4 ,quae unitas iuxta ,pythagorae opinionem rerum omnium principium est1 per cuius participationem unaquaeque res una dicitur4 ,quoniam enim nullo actio a materia potest nisi per contactum1 electrica haec non videntur tangere1 sed ut necesse erat demittitur aliquid ab uno ad aliud1 quod proxime tangat1 et eius incitationis principium sit4 ,corpora omnia uniuntur quasi ferruminantur quodammodo humore 444 ,electrica vero effi via peculiaria1 quae humoris fusi subtilissima sunt materia1 corpuscula allectant4 ,ar 7commune effluvium telluris7 partes disjunctis unit1 tellus mediante are ad se revocat corpora2 aliter quae in superioribus locis essent corpora1 terram non ita avide appelerent4 ,electrica effluvia ab are multum differunt1 u ar telluris effluvium est1 ita electrica suahabent effluvia propria2 peculiaribus effluviis suus cuique2 est singularis ad unitatem ductus1 motus ad principium1 fontem1 corpus effluvia emittens4 ,a similar hypothesis will reappear in his explanation of magnetic attraction4 #aai ,m3 pp4 #ia1 #ib3 ,this unity is1 according to ,pythagoras1 the principle1 through participation1 in which a thing is said to be one 7see footnotes #cj and #abb74 #abj ,sense is probably too strong a term1 and yet the change following contact is difficult to describe in ,gilbert's phraseology without some such subjective term4 ,see ,gilbert's argument on the soul and organs of a loadstone1 ,m3 pp4 #cji-cac4 #aba ,m3 pp4 #aab1 #aac4 #abb ,gilbert1 ,de magnete1 ,london1 #afjj1 bk4 #b1 ch4 #b1 pp4 #ef-eg4 ,following the tradition of the medieval schoolmen ,gilbert started his examination of the nature of the loadstone by pointing out the different kinds of motion due to a magnet4 ,the five kinds 7other than up and down7 are3#abc 7#a7 coitio 7vulgo attractio1 dicta7 ad unitatem magneticam incitatio4 7#b7 directio in polos telluris1 et telluris in mundi destinatos terminos verticitas et consistentia4 7#c7 variatio1 a meridiano deflexio1 quem motum nos depravatum dicimus4 7#d7 declinatio1 infra horizontem poli magnetici descensus4 7#e7 motus circularis1 seu revolutio4 ,of the five he initially listed1 three are not basic ones4 ,variation and declination he later explained as due to irregularities of the surface of the earth1 while direction or verticity is the ordering motion that precedes coition4#abd ,this leaves only coition and revolution as the basic motions4 ,how these followed from the congregant nature of the loadstone can be seen when the effusion of forms has been considered4 ,coition 7he did not take up revolution at this point7 differed from that due to other attractions4 ,there are two and only two kinds of bodies that can attract3 electric and magnetic4#abe ,gilbert refined his position further by arguing that one does not even have magnetic attraction#abf but instead the mutual motion to union that he called coition4#abg ,in electric attraction1 one has an action-passion relation of cause and effect with an external agent and a passive recipient2 while in magnetic coition1 both bodies act and are acted upon1 and both move together4#abh ,instead of an agent and a patient in coition1#abi one has conactus4 ,coition1 as the ,latin origin of the term denoted1 is always a concerted action4 #acj ,this can be seen from the motions of two loadstones floating on water4#aca ,the mutual motion in coition was one of the reasons for ,gilbert's rejection of the perpetual motion machine of ,peregrinus4#acb #abc ,ibid41 ch4 #a1 pp4 #de-df4 #abd ,m3 pp4 #aaj1 #cad4 #abe ,m3 pp4 #hb1 #aje1 #agj1 #agb1 #bag4 #abf ,m3 p4 #ih4 #abg ,m3 pp4 #ajj1 #aab1 #aac1 #adc1 #adh4 ,it need hardly be pointed out that coitus is not an impersonal term4 #abh ,m3 p4 #aaj4 #abi ,m3 p4 #aaj4 #acj ,m3 pp4 #aji1 #aae1 #adh1 #adi1 #aee1 #aff1 #agd4 #aca ,m3 pp4 #aaj1 #aee4 #acb ,m3 pp4 #aff1 #ccb4 ,see also footnote #hd4 ,magnetic coition1 unlike electric attraction1 cannot be screened4#acc ,hence it cannot be corporeal for it travels freely through bodies#acd and especially magnetic bodies2#ace one can understand the action of the armature on this basis4#acf ,since coition cannot be prevented by shielding1 it must have an immaterial cause4#acg #acc ,m3 pp4 #ij1 #ajf1 #ajg1 #ajh1 #aac1 #acb1 #ace1 #acf1 #aeh4 ,this is1 of course1 contrary to modern experience4 #acd ,m3 pp4 #ajf1 #ajg1 #ajh1 #aad1 #acd1 #acf1 #adj1 #afb4 #ace ,m3 pp4 #ajf1 #aji1 #aad1 #aei1 #afb4 #acf ,m3 pp4 #acg-adj4 #acg ,m3 p4 #aji4 ,yet1 unless one has the occult action-at-a-distance1 change must be caused by contact forces4 ,gilbert resolved the paradox of combining contact forces with forces that cannot be shielded1 by passing to a higher level of abstraction for the explanation of magnetic phenomena3 he saw the contact as that of a form with matter4 ,although ,gilbert remarked that the cause of magnetic phenomena did not fall within any of the categories of the formal causes of the ,aristotelians1 he did not renounce for this reason the medieval tradition4 ,actually there are many similarities between ,gilbert's explanation of the loadstone's powers and that of ,st4 ,thomas4 ,magnetic coition is not due to any of the generic or specific forms of the ,aristotelian elements1 nor is it due to the primary qualities of any of their elements1 nor is it due to the celestial generans of terrestrial change4#ach ,relictis aliorum opinionibus de magnetis attractione2 nunc coitionis illius rationem1 et motus illius commoventem naturam docebimus4 ,cum vero duo sint corporum genera1 quae manifestis sensibus nostris motionibus corpora allicere videntur1 ,electrica et ,magnetica2 ,electrica naturalibus ab humore effluviis2 ,magnetica formalibus efficientiis1 seu potius primariis vigoribus1 incitationes faciunt4 ,forma ilia singularis est1 et peculiaris1 non ,peripateticorum causa formalis1 et specifica in mixtis1 est secunda forma1 non generantium corporum propagatrix2 sed primorum et praeciporum globorum forma2 et partium eorum homogenearum1 non corruptarum1 propria entitas et existentia1 quam nos primariam1 et radicalem1 et astream appellare possumus formam2 non formam primam ,aristotelis2 sed singularem illam1 quae globum suum proprium tuetur et disponit4 ,talis in singulis globis1 ,sole1 lunas et astris1 est una2 in terra etiam una1 quae vera est ilia potentia magnetica1 quam nos primarium vigorem appellamus4 ,quare magnetica natura est telluris propria1 eiusque omnibus verioribus partibus1 primaria et stupenda ratione1 insita2 haec nec a caelo toto derivatur procreaturve1 per sympathiam1 per influentiam1 aut occultiores qualitates2 nec peculiari aliquo astro3 est enim suus in tellure magneticus vigor1 sicut in sole et luna suae formae2 frustulumque2 lunae1 lunatice ad eius terminos1 et formam componit se2 solarque2 ad solem1 sicut magnes ad tellurem1 et ad alterum magnetem1 secundum naturam sese inclinando et alliciendo4 ,differendum igitur de tellure quae magnetica1 et magnes2 tum etiam de partibus eius verioribus1 quae magneticae sunt2 et quomodo ex coitione difficiuntur4 ,instead1 he declared it to be due to a form that is natural and proper to that element that he made the primary component of the earth4#aci ,to understand his argument1 let us briefly recall the peripatetic theory of the elements4 ,in this philosophy of nature each element or simple body is a combination of a pair of the four primary qualities that informs inchoate matter4 ,these qualities are the instruments of the elemental forms and determine the properties of the element4 ,thus the element fire is a compound of the qualities hot and dry1 and the substantial form of fire acts through these qualities4 ,similarly for the other elements1 earth1 water1 and air3 their forms determine a proper place for each element1 and a motion to that place natural to each element4#adj #ach ,m3 p4 #aje1 and ,gilbert1 ,de magnete1 ,london1 #afjj1 bk4 #b ch4 #d1 p4 #fe4 #aci ,m3 p4 #aje4 #adj ,m3 pp4 #bhi1 #cbb4 ,gilbert had previously declared that the primary substance of the earth is an element4 ,since it is an element1 it has a motion natural to it1 and this motion is magnetic coition4 ,as an ,aristotelian considered the substantial form of the element1 fire1 to act through the qualities of hot and dry1 and to cause an upward motion2 so ,gilbert argued that the substantial form of his element1 pure loadstone1 acts through the magnetic qualities and causes magnetic coition4 ,this motion is due to its primary form1 and is natural to the element earth4#ada ,it is instilled in all proper and undegenerate parts of the earth1#adb but in no other element4#adc #ada ,m3 pp4 #bf1 #fh1 #aje1 #agi1 #aih1 #cjg1 #cce1 #cdc4 ,for rotation1 see footnote #adg4 #adb ,m3 pp4 #fg1 #ga4 ,that each part is informed with the properties of the whole is an argument favoring an animistic explanation of the nature of this form4 #adc ,m3 p4 #aji4 ,to the medieval philosopher1 the generantia of the occult powers of the loadstone are the heavenly bodies4 ,gilbert1 however1 endowed the earth with these heavenly powers which were placed in the earth in the beginning#add and caused all magnetic materials to conform with it both physically and formally4#ade ,such magnetic powers are the property of all parts of the earth2#adf they give the earth its rotating motion#adg and hold the earth together in spite of this motion4#adh #add ,m3 pp4 #aaa1 #ahh4 #ade ,m3 pp4 #fg1 #aje1 #agi1 #ahc4 #adf ,m3 pp4 #aja1 #aje1 #bag4 #adg ,m3 pp4 #agi1 #cjd1 #cje1 #caa1 #cbb1 #cbf1 #cbh1 #ccj-ccd1 #cch-cdc4 #adh ,m3 pp4 #adb1 #agi2 see also electric attraction1 p4 #ig4 ,indeed1 each of the main stellar bodies1 sun1 moon1 stars1 and earth1 has such a form or principle unique to itself that causes its parts not only to conform with itself but to revolve4#adi ,thus1 if one removes a piece of the moon from this body1 it will tend to align itself with the moon and then to return to its proper place2 and a fragment of the sun would similarly tend to return after proper orientation4#aej ,moreover1 there is a farther-ranging1 though weaker1 mutual action of the heavenly bodies so that one has a causal hierarchy of these specific conforming powers4 ,the form of the sun is superior to that of the inferior globes and is responsible for the order and regularity of planetary orbits4#aea ,in like manner1 the moon is responsible for the tides of the ocean4#aeb #adi ,m3 pp4 #cjh1 #cag-cdc4 #aej ,m3 pp4 #ajf1 #cdj4 #aea ,m3 pp4 #cjh1 #cji1 #caa1 #ccj1 #ccc1 #cdd1 #cdg4 #aeb ,m3 pp4 #acf1 #ccd1 #cde4 ,by virtue of the causal hierarchy of forms1 the loadstone acquires its magnetic powers from the earth4#aec ,as the earth has its natural parts1 so has the stone4#aed ,although the geometrical center of a terrella is the center of the magnetic forces1#aee objects do not tend to move to the center but to its poles1#aef where the magnetic energy is most conspicuous4#aeg ,however1 in a sense1 the energy is everywhere equal3 the virtue is spread throughout the entire mass of the loadstone1#aeh and all the parts direct the forces to the poles4#aei ,the poles become the thrones of the magnetic powers4#afj ,on the other hand1 the directive force is stronger where coition is weaker and accordingly1 verticity is most prominent at the equator4#afa #aec ,m3 pp4 #ahd-ahf1 #aij1 #bcb4 ,this is not quite the same argument as that the powers of the loadstone are identical with those of the earth4 ,see footnote #gh4 #aed ,m3 pp4 #abe1 #ahj4 #aee ,m3 p4 #aea4 #aef ,m3 pp4 #aba1 #aej4 #aeg ,m3 pp4 #aae1 #aea1 #afe4 #aeh ,m3 pp4 #ajf1 #aah1 #aea1 #aia1 #bje1 #bba1 #bdc4 #aei ,m3 pp4 #aaf1 #aag1 #aai1 #aca1 #ahc1 #ahh1 #bba4 #afj ,m3 p4 #ca4 #afa ,m3 pp4 #aaf1 #aea1 #bjj4 ,the strength of a loadstone depends upon its shape and mass4 ,a bar magnet has greater powers than a spherical one because it tends to concentrate the magnetic powers more in the ends4#afb ,for a given purity and shape1 the heavier the loadstone1 the greater its strength4#afc ,a loadstone has a maximum degree of magnetic force that cannot be increased4#afd ,however1 weaker ones can be strengthened by stronger ones4#afe ,similarly1 the shape and weight of the iron determine the magnetic force in coition4#aff #afb ,m3 pp4 #aca1 #acb1 #aec-aeh4 #afc ,m3 pp4 #ada1 #aeb1 #aec1 #aeh1 #afa1 #aia1 #bbb4 #afd ,m3 p4 #adf4 #afe ,m3 p4 #afe4 #aff ,m3 p4 #aec4 ,the formal forces of a loadstone emanate in all directions from it1#afg but there is a bound to it that ,gilbert called the orbis virtutis4#afh ,the shape of this orbis virtutis is determined by the shape of the stone4#afi ,this insensible effusion is analogous to the spreading of light that reveals its presence only by opaque bodies4#agj ,similarly1 the magnetic forms are effused from the stone1#aga and can only reveal their presence by coition with another loadstone or by awakening magnetic bodies within the orbis virtutis4#agb ,unmagnetized iron that comes within the orbis virtutis is altered1 and the magnetic virtue renews a form that is already potentially in the iron4#agc ,the formal energy is drawn not only from the stone but from the iron4#agd ,this is not generation1 or alteration in the sense of a new impressed quality1 but alteration in the sense of the entelechy or the activation of a form potentially present4#age ,those bodies magnetized by coming within the orbis virtutis have in turn an efflux of their own4#agf ,iron can also receive verticity directly from the earth without the intervention of an ordinary loadstone4#agg ,such verticity can be expelled and annulled by the presence of another loadstone4#agh #afg ,m3 pp4 #aba1 #abc1 #abd1 #cjd1 #cje1 #cjf1 #cjg1 #cji4 #afh ,gilbert defined the orbis virtutis in the glossary at the beginning of his treatise as1 444 totum illud spatium1 per quod quaevis magnetis virtus extenditur4 ,this is the core of the difference between electric and magnetic forces4 ,the substantial form of an electric could not be effused1 but was imprisoned in matter 7as the ,neoplatonic soul in the human body72 while the primary form of a magnet did not require a material carrier and its effusion was similar to the propagation of a species in light4 #afi ,m3 pp4 #abd1 #aej1 #aea4 #agj ,m3 pp4 #abc1 #cjg4 #aga ,m3 pp4 #cjd-cjg4 ,see also p4 #caj1 where it is stated that the sun and earth could awaken souls4 #agb ,m3 pp4 #aja1 #aaj1 #aab1 #abc1 #adh1 #adi1 #cjd1 #cje4 ,this awakening of the iron within the orbis virtutis is comparable 7pp4 #baf1 #cej7 to the birth of a child under the influence of the stars4 #agc ,m3 pp4 #aaj1 #aaa1 #aab1 #ahi1 #baf1 #bag4 ,see also footnote #cf4 #agd ,m3 p4 #ajf4 #age ,m3 pp4 #ajf1 #aji1 #aaj4 #agf ,m3 pp4 #aac1 #aad4 #agg ,m3 pp4 #aij1 #aib1 #baj-baf4 #agh ,m3 p4 #bji4 ,although one does not normally find iron to be magnetized1 a loadstone always has some magnetism4 ,that two bodies such as iron and loadstone should have different properties is the result of the loss of a form by the iron1 but this form is still potentially present in the iron4 ,the iron that has been obtained from an ore has been deformed1#agi for it has been placed outside its nature by the fire4#ahj ,the nature has not been removed1 since1 once the iron has cooled1 the confused form can be reformed by a loadstone4 #aha ,the latter awakens the proper form of iron4#ahb ,after smelting1 the magnetized iron may manifest stronger powers than a loadstone of equal weight1 but this is because the primary matter of the earth is purer in the iron than in the loadstone4#ahc ,if fire does not deform a loadstone too much1 it can be remagnetized1#ahd but a burnt loadstone cannot be reformed4#ahe ,corruption from external causes may also deform a loadstone or iron so that it can not be magnetized4#ahf ,bodies mixed with the degenerate substance of the earth or with aqueous humor spoilt by contamination with earth1 do not show either electric attraction or magnetic coition4#ahg #agi ,m3 pp4 #ajg1 #aaj1 #aaa4 #ahj ,m3 p4 #ajh4 #aha ,m3 pp4 #aaa1 #aab1 #aac4 #ahb ,m3 pp4 #aji1 #aaa1 #aab1 #adh1 #adi4 #ahc ,m3 pp4 #aab1 #adi4 #ahd ,m3 pp4 #adb1 #ahi4 #ahe ,m3 p4 #aij4 #ahf ,m3 pp4 #he1 #aje1 #aac1 #adc1 #bbf4 #ahg ,m3 p4 #hd4 ,in a manner suggestive of ,peregrinus1 ,gilbert wrote that1 magnetic bodies seek formal unity4#ahh ,thus a dissected loadstone not only tends to come back together1 as in the unordered coacervation of electric attraction1 but to restore the organization it had before dissection4#ahi ,accordingly1 opposite poles appear on the interfaces of the sections1 not from an opposition but from a concordance and a conformance4#aij ,this ensures that when the parts are joined together again1 they have the same orientation as before4 ,gilbert compared this power of restoring the original loadstone with that of a plant's vital power under the process of cutting and grafting2 the plant can be revived only when the parts are in a certain order4#aia #ahh ,m3 p4 #ahf4 #ahi ,m3 pp4 #ahe-ahh4 ,see also footnote #ca4 #aij ,m3 pp4 #ahf1 #aic4 #aia ,m3 pp4 #aii-bjj4 ,a hypothesis similar to that used to explain electric attraction lay beneath the explanation of magnetic coition3 that bodies brought into contact will move together4 ,in electric attraction1 the contact is material and due to the spiritus from the electric body2 in magnetic coition1 it is formal and depends on the action of a primary form that spreads from a magnetized body to its limit of effusion1 the orbis virtutis4 ,if iron is inside the orbis virtutis1 the two bodies enter into alliance and are one and the same#aib for within it they have absolute continuity1 and are joined by reason of their accordance1 albeit the bodies themselves be separated4#aic ,gilbert's treatment of coition can be analyzed into the same two steps as can electric attraction4 ,first occurs a contact1 which in this case is not physical but formal1 and from this initial formal contact follows movement to a more complete unity4 ,both the contact and the movement to unity are described on the same level of abstraction1 instead of on two different levels as in electric attraction4 ,again one does not find any clear-cut concept of force as a push or pull1#aid but instead1 a motion to a formal unity1 this time a cooperative motion4 ,the parts of a magnetic body are in greater harmony when they are assembled in a certain pattern and so they move accordingly4 #aib ,m4 p4 #aaa4 #aic ,m3 p4 #aab4 #aid ,see1 however1 ,m3 pp4 #aab1 #aac4 ,as to the nature of the primary form itself1 ,gilbert agreed with ,thales that it is like a soul1#aie for the power of self-movement seems to betoken a soul4#aif ,with ,galen and ,st4 ,thomas he placed the form of the loadstone superior to that of inanimate matter4#aig ,in a sense1 ,gilbert even made it superior to organic matter1 for it is incapable of error4#aih ,like the soul1 the primary form cannot be fragmented2 when a loadstone is divided1 one does not separate the poles but each part acquires its own poles and an equator4 #aie ,m3 pp4 #aji1 #cab4 #aif ,m3 p4 #aji4 #aig ,m3 p4 #cji4 #aih ,m3 pp4 #caa-cab4 ,like the soul1 fire does not destroy it4#aii ,like the soul of astral bodies1 and of the earth itself1 it produces complex but regular motions2 the motion of two loadstones on water offers such an example4#bjj ,like the soul of a newborn child1 whose nature depends on the configuration of the heavens1 the properties in the newly awakened iron depend upon its position in the orbis virtutis4#bja ,whence ,gilbert declared3 444 the earth's magnetic force and the animate form of the globes1 that are without senses1 but without error 444 exert an unending action1 quick1 definite1 constant1 directive1 motive1 imperant1 harmonious through the whole mass of matter2 thereby are the generation and the ultimate decay of all things on the superficies propagated4#bjb ,the bodies of the globes 444 to the end that they might be in themselves1 and in their nature endure1 had need of souls to be conjoined to them1 for else there were neither life1 nor prime act1 nor movement1 nor unition1 nor order1 nor coherence1 nor conactus1 nor sympathia1 nor any generation nor alteration of seasons1 and no propagation2 but all were in confusion4444#bjc ,wherefore1 not with reason1 ,thales 444 declares the loadstone to be animate1 a part of the animate mother earth and her beloved offspring4#bjd ,gilbert ended book #e of his treatise on the magnet with a persuasive plea for his magnetic philosophy of the cosmos1 yet his conceptual scheme was not too successful an induction in the eyes of his contemporaries4 ,in particular the man from whom the ,royal ,society took the inspiration for their motto1 ,nullius in verba1 did not value his magnetic philosophy very highly4 ,whether ,francis ,bacon was alluding to ,gilbert when he expounded his parable of the spider and the ant#bje is not explicit1 but he certainly had him in mind when he wrote of the ,idols of the ,cave and the ,idols of the ,theater4#bjf #aii ,m3 p4 #ajh4 #bjj ,m3 p4 #aaj4 #bja ,m3 p4 #baf4 #bjb ,m3 p4 #caa4 #bjc ,m3 pp4 #caj1 #caa4 #bjd ,m3 p4 #cab4 #bje ,francis ,bacon1 op4 cit4 7footnote #db71 vol4 #a1 ,novum organum1 bk4 #a1 ch4 #ie1 p4 #cjf4 #bjf ,ibid41 ch4 #ed and ch4 #fd 7pp4 #bei and #bfg74 ,few of the subsequent experimenters and writers on magnetism turned to ,gilbert's work to explain the effects they discussed4 ,although both his countrymen ,sir ,thomas ,browne#bjg and ,robert ,boyle#bjh described a number of the experiments already described by ,gilbert and even used phrases similar to his in describing them1 they tended to ignore ,gilbert and his explanation of them4 ,instead1 both turned to an explanation based upon magnetic effluvia or corpuscles4 ,the only direct continuation of ,gilbert's ,de magnete was the ,philosophia magnetica of ,nicolaus ,cabeus4#bji ,the latter sought to bring ,gilbert's explanation of magnetism more directly into the fold of medieval substantial forms4 #bjg ,sir ,thomas ,browne1 ,pseudodoxia epidemica1 ed4 #c1 ,london1 #afeh1 bk4 #b1 ch4 #b1 #c1 #d4 #bjh ,robert ,boyle1 ,experiments and notes about the mechanical production of magnetism1 ,london1 #afgf4 #bji ,nicolaus ,cabeaus1 ,philosophia magnetica1 ,ferarra1 #afbi4 ,however1 ,gilbert's efforts towards a magnetic philosophy did find approval in two of the men that made the seventeenth century scientific revolution4 ,while ,galileo ,galilei#baj was critical of ,gilbert's arguments as being unnecessarily loose1 he nevertheless saw in them some support for the ,copernican world-system4 ,johannes ,kepler#baa found in ,gilbert's explanation of the loadstone-earth a possible physical framework for his own investigations on planetary motions4 #baj ,galileo ,galilei1 ,dialogue on the great world systems1 in the translation of ,t4 ,salusbury1 edited and corrected by ,g4 de ,santillana1 ,university of ,chicago ,press1 #aiec1 pp4 #dji-dbc4 #baa ,cassirer1 op4 cit4 7footnote #c71 vol4 #a1 p4 #cei-cfg4 ,yet ,galileo and ,kepler had moved beyond ,gilbert's world of intellectual experience4 ,they were no longer concerned with determining the nature of material things in order to explain their qualities4 ,instead1 they had passed into the realm of the mathematical relations of kinematics3 quantitative law had replaced qualitative experience of cause and effect4 ,gilbert had some intimations of the former1 but he was primarily concerned with explaining magnetism in terms of substance and attribute4 ,he had to ascertain the nature of the loadstone and of the earth in order to explain their properties and their motions4 ,he even went further and explained the nature of the form of the loadstone4 ,his method of determining the nature of a substance was a rather primitive one--it was not by a process of induction and deduction1 nor by synthesis and analysis1 nor by resolutio and compositio1 but by the use of analogies4 ,he compared the natural history of metals and rocks with that of plants1 and gave the two former the same kind of principle as the last4 ,he determined the nature of the entity behind electric attraction by finding that such attractions could be screened1 and hence it had to be corporeal4 ,after comparing this corporeal attraction with that of the surface forces of a fluid1 he concluded that the entity was a subtle fluid4 ,he determined the nature of the entity behind magnetic coition by 7incorrectly7 finding that it cannot be screened1 and hence the cause had to be a formal one4 ,since both stars and the loadstone can carry out regular motions1 and stars had souls1 the form of the loadstone had to be a soul4 ,the method of analogy was used again in his comparison of the properties of a magnetized needle placed over a terrella with the properties of a compass placed over the earth1 whence he concluded the earth to be a giant loadstone4 ,since the earth resembled the other celestial globes1 it had to have1 the circular inertia of these globes4#bab ,as for his magnetic experiments to show physically that the earth moved1 and his unbridled speculations on the animae of the celestial globes1 one is inclined to agree with ,bacon's estimate of his magnetic philosophy4 ,one might consider ,gilbert's book as a ,renaissance recasting of ,aristotle's ,de caelo with the earth in the role of a heavenly body4 ,so it might well be1 for ,gilbert was still concerned with distinguishing the nature of the heavenly body1 earth1 that caused the coitional and revolving motions1 from those natures for which up and down1 and coacervation were the natural motions4 ,because the natural motions were different1 the natures had to be different1 and these different natures led to a universe and a concept of space neither of which were ,aristotelian4 ,one no longer had a central reference point for absolute space2 there was no motor essentialis focused upon the earth but one had only the mutual motion of the heavenly bodies4 ,the natural distinction between heaven and earth was gone1 for the earth was no longer an inert recipient but a source of wonder1 and so the stage was set for the universe of ,giordano ,bruno4#bac ,the ,aristotelian philosophy of nature was used to justify a new cosmology1 but there was no break with the past such as one finds in ,galileo and ,kepler4 ,instead he followed the chimera of the world organism1 as ,paracelsus had1 and of the world soul1 as ,bruno had4 ,consequently ,gilbert's physiology did not enter into the main stream of science4 #bab ,because the earth has the same nature as a celestial globe1 its revolution and circular inertia require no more explanation than those of any other heavenly body4 #bac ,one wonders if ,bruno might not have been another of the stimuli for ,gilbert4 ,the latter's interest in magnetism began shortly before ,bruno visited ,england and lectured on his interpretation of the ,copernican theory4 ,yet this is not to deny ,gilbert's services to natural philosophy4 ,although not all of his experimental distinction between electric and magnetic forces has been retained1 still1 some of it has4 ,his orbis virtutis was to become a field of force1 and his class of electrics1 insulators of electricity4 ,his practice of arming a loadstone was to be of considerable importance in the period before the invention of the electromagnet4 ,his limited recognition of the mutual nature of forces and their quantitative basis in mass was ultimately to appear in ,newton's second and third laws of motion4 ,in spite of the weaknesses of the method of analogy1 ,gilbert's experimental model of the terrella to interpret the earth's magnetism was as much a contribution to scientific method as to the theory of magnetism4 ,consequently1 in spite of an explanation of electricity and magnetism that one would be amused to find in a textbook today1 we can still read his ,de magnete with interest and profit4 ,but more important than his scientific speculations1 is the insight he can give us into a ,renaissance philosophy of nature and its relation to medieval thought4 ,one does not find in ,de magnete a prototype of modern physical science in the same sense one can in the writings of ,galileo and ,kepler4 ,instead one finds here a full-fledged example of an earlier kind of science1 and this is ,gilbert's main value to the historian today4