196 W. A. WALLACE 



velocities of fall of such bodies, and not the places to which 

 they tend, his elimination of specific weights as of incidental 

 importance would have shown rare insight for his time. But 

 there is no mention of velocities in this opusculum, and this 

 discovery had still to await the researches of Galileo. 



It is by pursuing such a line of thought, however, that 

 Theodoric comes to some interesting questions about composite 

 motions and how these can be resolved into component parts, 

 for which he proposes noteworthy answers. He maintains, in 

 accordance with the teaching just proposed, that there are no 

 " intermediary places . . . beyond the four places of the four 

 primary bodies," although allowing that a particular compound 

 might have a proper place to which it tends in " some one of 

 these first regions," determined by its " relation to some part 

 of the heavens or the horizon." ^^ Against this position he notes 

 the objection, already in Aristotle, that simple bodies ought 

 to have simple motions and composite bodies composite mo- 

 tions. He replies to this by making precise the sense in which a 

 motion is " composite " — not because its terminus is composite, 

 but rather because " the manner in which it tends to that 

 terminus is composite." This manner of tending, he points out, 

 need not be composite, for we find that both simple and com- 

 posite bodies undergo simple motions " according to the nature 

 of the predominant." In fact, he notes, such simple motions 

 are what manifest the natures of the simple bodies or elements, 

 and it matters little whether the body undergoing motion be 

 simple or composite when the motion itself is simple and mani- 

 fests the simple nature that is its principle .^^ 



Yet it is a fact that some composite bodies have simple 

 natural motions, while others have composite natural motions — 



^* Cap. 10, M 14vb, U 141vb: Non est eciam aliquis locus medius, vel ut ita 

 dicam mixtus, preter hec quatuor loca quatuor corporum primorum. Unde neces- 

 sarium est omne corpus recti motus ferri ad aliquem istorum quatuor secundum 

 predominans, et si fuerit aliquis locus proprius aJicui mixto secundum habitudinem 

 ad aliquam partem celi vel orizontis, hie erit pars alicuius istorum primorum locorum 

 et presupposita natura ipsius. 



"Cap. 11, M 15ra, U 142ra. 



