164 JAMES A. WEISHEIPL 



cient causality includes the universal agency of celestial bodies 

 operating in elementary bodies and in animal reproduction: 



Even among naturalists it is admitted that above those contrary 

 agencies in nature there is a single first agent, namely the heaven, 

 which is the cause of the diverse motions in those lower bodies. 

 But since in the very heaven there is observed a diversity of posi- 

 tion to which the contrariety of lower bodies is reduced as to a 

 cause, [this diversitj^] must further be reduced to a first mover who 

 is moved neither 'per se nor per accidens.^^ 



Similarly the argument from possible and necessary beings 

 includes not only terrestrial necessities and contingencies, but 

 also the sempiternal celestial bodies and spiritual substances, 

 which are radically necessary beings. Their necessity for being 

 can, indeed, be seen as derived; therefore beyond them there 

 must exist an absolutely necessary being whose necessity is in 

 no way derived. *° The Platonic, or more specifically, the Avi- 

 cennian *^ argument concerning perfections clearly includes the 

 immutable celestial bodies in the participated inequality of 

 being and goodness, an inequality which needs to be derived 

 from a single source which is essentially being, goodness and 

 supreme perfection. The fifth argument likewise includes the 

 influence of celestial bodies and separated intelligences on 

 natural operations.*" Natural terrestrial operations, influenced 

 by celestial motions, the light and heat of the sun, are appar- 

 ently purposeful operations of nature; all such operations of 

 nature require the direction of intelligence {cypus naturae est 

 opus intelligentiae) . 



Historically, then, the five proofs of St. Thomas for the exist- 

 ence of God involve celestial bodies and their movement as 

 he understood them. Therefore a careful consideration of celes- 

 tial phenomena in the physics of St. Thomas is not without 



^* St. Thomas, De pot., q. 3, a. 6. 

 *° St. Thomas, De pot., q. 5, a. 3. 

 *^ De pot., q. 3, a. 5. 



*'' De verit., q. 5, a. 2; Sum. contra gentiles, I, cap. 13. Cf. Averroes, In II Phys., 

 comm. 75. 



