200 W. A. WALLACE 



Unfortunately he does not discuss the character of the extrinsic 

 principle in this context. However, when attempting later to 

 account for the fact that mists arise naturally from ponds and 

 move in determined directions, he explains that the generating 

 agent " continually induces some natural disposition into such 

 bodies," which is not gravity but " which presupposes and 

 requires this qualitative principle," and is similarly related to 

 a determinate place.^^ Such an added disposition, he observes, 

 is the means by which "universal nature " provides for the 

 needs of the various parts of the universe, as for example by 

 moving rain clouds to particular areas where water is needed.^^ 

 The added disposition he also calls a " generative principle," 

 and notes that its action is not a violent one, even though 

 attraction and propulsion characterize its operation. He would 

 prefer to speak of the propulsion as arising from " whatever 

 induces the form or disposition which is the principle of the 

 motion," and to understand the attraction as being merely 

 in the order of final causality.-^ 



Thus Theodoric analyzes certain composite motions found 



^^ Cap. 17, M 15va, U 142vb: Sed si sunt alia aliqua corpora huius inferioris 

 mundi que moveantur per naturam motu tortuoso vel composito vel circulari, 

 huiusniodi eciam movebuntur ab exteriori principio, et hoc sive a generante, inquan- 

 tum videlicet talibus corporibus continue influit aliquam disposicionem naturalem 

 qua acquiratur eis continue locus post locum, non semper secundum habitudinem 

 recte distancie que attenditur inter centrum et circumferenciam secimdum lineam 

 rectam. Talis enim motus principium est generans, secundum quod ingenerat 

 corporibus has simplices et absolutas qualitates que sunt gravitas et levitas. Pre- 

 diotis autem corporibus aliquando acquiritur locus continue secundum habitudinem 

 ad aliquam partem orizontis, ut si surgat aliquis vapor in parte australi et per 

 naturam tendat versus septentrionem. Hoc autem fit secundum aliquam aliam 

 disposicionem huiusmodi corporibus inditam, que nee est gravitas neque levitas. 

 Presupponit tamen et preexigit hoc qualitativum principium, sic inditum per 

 naturam, gravitatem et levitatem in corpore in quo est, sicut et locus in quo vel 

 ad quem moventur huiusmodi corpora est pars alicuius locorum gravium et levium. 



^"Cap. 18, M 15va, U 142vb-143ra. 



^ Cap. 19, M 15va, U 143ra: Huic motui corporum que moventur per principium 

 generativum commune assimilatur motus et nutrimenti per corpus. . . . Intelligenda 

 est pulsio et tractio modo predicto proporcionaliter, sicut in predictis corporibus 

 partibus mundi, ut scilicet dicatur pellens eo quod dat formam vel disposicionem 

 que est principium motus, trahens autem intelligatur secundum racionem et inten- 

 cionem finis. . . . 



