CELESTIAL MOVERS IN MEDIEVAL PHYSICS 177 



Replying to the first question, Kilwardby explicitly denies 

 that God is the immediate mover of the heavens moving either 

 eternally or temporally in place: certissime tenendum est et 

 asserenduTn quod Deus non movet "priraum caeluTn nee aliquod 

 corpus immediate motu localiJ^ He admits that Aristotle 

 seems to consider God as the first mover of the eternal spheres, 

 " but the truth is that God does not move any body immedi- 

 ately " by continual locomotion. If God did move any body 

 in this way, He would be either the substantial act of that body 

 and a part of the whole or a simple mover like a man on a horse. 

 The first alternative is obviously erroneous. The second is 

 awkward and unreasonable for it implies that the first heaven 

 is moved by violence: secundo modo caelum primuTn videre- 

 tur moveri violenter. Kilwardby, however, does admit that 

 God can and does move bodies immediately by a certain 

 supernatural change, as in creation, the production of light, 

 the formation of Eve and similar events. In such events God 

 operates without the assistance of nature or angels. Concluding 

 his reply to the first query, Kilwardby categorically states: 



From these considerations, therefore, the reply to the question 

 must be that God moves no body immediately by continuous 

 motion, but only by His word when a body is changed instan- 

 taneously so that something supernaturally begins to exist. 



The second question has to do with natural motions and their 

 dependence on angelic movers of the celestial bodies. Kil- 

 wardby first distinguishes between natural and violent motions. 

 Nature is an intrinsic principle of motion; only bodies which 

 have such a principle per se are said to move naturally. Mo- 

 tions are called violent when their moving force is extraneous, 

 the subject contributing nothing to the motion (quando prin- 

 cipiwm motivum est extraneum, passo non conjerente) . Among 

 natural motions Kilwardby enumerates continuous movement 

 of bodies, instantaneous transmission of light, the irascible and 

 concupiscible emotions of spiritual beings, and intellectual ac- 

 tivity. Clearly, intellectual and appetitive activities of spiritual 



''^ Kilwardby, Responsio, q. 1, ed. Chenu, loc. cit., p. 194. 



