GRAVITATIONAL MOTION 215 



favor the Averroistic explanation, as evidenced by this text 

 where he explicitly rejects Avempace's solution: 



It is obvious from what has been said that Avempace's position, 

 which the Commentator [Averroes] treats in the context of the 

 fourth book of the Physics, is false. This states that if all impedi- 

 ments be removed, taking away even corporeal media through 

 Avhich heavy and hght bodies move, supposing imaginatively that 

 the medium were void, that nonetheless heavy and light bodies 

 would be moved by nature with a determinate velocity and slow- 

 ness in time. According to the foregoing, however, this is only 

 possible where the mover and the thing moved are actually distinct, 

 and where the mover is also actually conjoined to the moved 

 according to a determinate proportion between the power of the 

 mover and the thing moved, as is the case with animals and 

 heavenh^ bodies. This would also render false the demonstration 

 of the Philosopher [Aristotle] in the fourth book of the Physics, 

 where he shows that heavy and light bodies do not move in a void, 

 as the Commentator sufficiently explains, nor need we delay over 

 this.°^ 



Theodoric's treatment of gravitational motion is consistently 

 concerned with the natural or physical causes of such motion, 

 and is devoid of quantitative or mathematical considerations. 

 In this respect his methodology in mechanics is significantly 

 different from that found in his optical studies, where experi- 

 mental and mathematical techniques reached their highest 

 development within the hochscholastik period. This difference 

 was noted in my earlier study, where I assigned it to the 

 obscurity of the principles available for explaining gravita- 

 tional motion (and chemical change) , forcing Theodoric to 

 remain at the qualitative and dialectical level when treating 

 these matters.®® Yet the conclusion need not be draAvn that 

 Theodoric's opuscula were without value for the later develop- 

 ment of the science of mechanics. Both Maier and Clagett 

 have shown how the mid-fourteenth century opuscula of writers 

 like Buridan began to change the ' climate of opinion,' and 



"^ Cap. 44; Latin text given by Maier, Studien V, p. 246, fn. 14. 

 "" Scientific Methodology, pp. 127, 246-247. 



