inanimate motion in\-olvcd the action and passion 

 of an active external moxer and a passive capacity 

 lo be moved. W'lienee ihe delinilion of motion that 

 Descartes '•' was later lo deride, "motus est actus 

 entis in potenlia prout quod in potentia." 



We have seen above that the "motor essentialis" 

 for terrestial change is the "virtus coeli." Thus the 

 enacting source of all motion and change is the 

 heavens and the heavenly powers, while the earth 

 and its inhabitants becomes the focus or passive 

 recipient of these actions. In this manner the scholastic 

 restated in philosophical terms the drama of an 

 earth-centered universe. 



Although change or motion is normally elTected 

 through the above mentioned causal hierarchy, it is 

 not always necessary that actualization pass from the 

 First Cause clown through each step of the hierarchy 

 to terminate in the Cjualities of the individual being. 

 Some of the steps could be by-passed: for instance 

 man's body is under the direct influence of the 

 celestial bodies, his intellect under that of the angels 

 and his will under God.™ 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 load- 

 stone over iron. Such causal relations, where some 

 members of the normal causal chnin have been 

 circumvented, are called occult.-' 



While St. Thomas referred to the loadstone in a 

 number of places as something whose nature and 

 occult properties are well known, it was always as 

 an example or as a tangential reference. One does 

 not find a systematic treatment of the loadstone in 

 St. Thomas, but there are enough references to 



" Rc-ne Descartes, Oeiivres, Charles Adam and Paul Tannery, 

 Paris, 1897-1910, vol. 2, p. 597 (letter to Mersenne, 16 Oct., 

 1639), and vol. 11 (Le Monde), p. 39. The original defini- 

 tion can be found in Ari.stotlc, Physics, tran.slated by P. H. 

 Wickstcad and F. M. Oornford, Loeb Cla.ssical Library, 

 London, 1934, 201alO. .\cjuinas rephrases the definition as 

 "Molus est aclus exislenlis in potenlia secundum quod Imius modi." 

 Sec St. Thomas Aquinas, Opera omnia, Antwerp, 1612, vol. 2, 

 Physicorum Aristotelis exposilio, lib. 3, lect. 2, cap. a, p. 29. 



™ St. Thomas Aquinas, op. cit. (footnote 1 9), vol. 9, Summa 

 contra gentiles, lib. 3, cap. 92 (Quo modo dicitur aliquis bene 

 fortunatus et quo modo adjuvalur homo ex superioribus causis), 

 p. 343. 



" St. Thomas Aquinas, op. cil. (footnote 19), vol. 17 Opus- 

 ctila, De operationihus occultis naturae ad queindam militem uUramon- 

 tem, pp. 213-224 



provide a fairly explicit statement of what he con- 

 sidered to be the nature of the magnet. 



In one of his earliest writings, St. Thomas argued 

 that the magnet attracts iron because this is a necessary 

 consequence of its nature. ■• 



Respondeo dicendum. t[iiod omnibus reljus naturaliler 

 insunt quacdam principia. quibus non solum operationes 

 proprias cfficere possunt, sed quibus etiam eas convenientcs 

 liiii suo rcddanl, sive sint artiones quae consequantur rem 

 aliquam ex nalura sui generis, sive consequantur ex nalura 

 speciei, ut magncti compelit fcni deorsum ex nalura sui 

 generis, et attrahere ferrum ex natura speciei. Sicut aulem 

 ill rebus agenlibus ex necessitate naturae sunt principia 

 actionum ipsae formae, a ciuibus operationes proprie prodc- 

 unl convenientes fini. . . . 



Due to its generic form, the loadstone is subject to 

 natural motion of place of up and down. However, 

 the "virtus" of it.s specific form enabled it to produce 

 another kind of motion — it could draw iron to itself. 



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 

 substance, on the relatively passive qualities of 

 another. St. Thomas asserted the loadstone to be 

 one of these minerals, the occult powers of whose 

 form goes beyond those of the prime qualities.'^' 



I'orma enim elenienli non habcl aliquam operationcm 

 nisi quae fit per qualitates aclivas et passivas, quae sunt 

 disposiiiones materiae corporalis. I'orma autem corporis 

 mineralis habet aliquam operalionem e.xcedentem qualitates 

 aclivas el passivas, quae consequilur speciem ex influentia 

 corporis coelestis, ut quod magnes attrahit ferrum, et quod 

 saphirus curat apostema. 



That this occult power of the loadstone is a result 

 of the direct influence of the "virtus coeli" was 



-- St. Thomas .Aquinas, op. cil. (footnote 19), vol 7, .Scriplum 

 in quarlum lilirum senlenliarum magisiri Petri Lomhaidi, lib. 4, disq. 

 33 (De diversis coniugii legibus), art. 1 (Utrum habere phires 

 uxores sit contra legem naturae), p. 168. The same statement 

 occurs in one of his most mature works, op. c'l. vol. 20, Summa 

 Iheologica, pars 3 (supplementum), quaestio 65 (De pliiralitate 

 uxorum in quinque articulos divisa), art. 1 (L"trum habere 

 plures uxores sit contra legem naturae), p. 107. 



= > St. Thomas Aquinas, op. cil. (footnote 19), vol. 8, Qtiaestio 

 unica: de spinlualthus creaturis, art. 2 (Utrum substantia spiri- 

 tualis possit uniri corpori), p. 404. See also vol. 9, Summa 

 contra gentiles, lib. 3, cap. 92 (Quomodo dicitur aliquis bene 

 fortunatus, et quomodo adjuvalur homo ex superioribus causis), 

 p. 344; and vol. 17, Opuscula, De operalionibus occultis naturae ad 

 queindam militem ullramonlrm. pp. 213-214. 



126 



BULLI-.TIN 218: CONTRIBUTIONS FROM THE MUSKUM < )l I11SU)R^ AND TEC:HNOLOG^■ 



