CELESTIAL ZMOVERS IN IMEDIEVAL PHYSICS 163 



depend upon the antiquated astronomy of the Middle Ages. 

 The principle of each proof has universal validity and the line 

 of argumentation transcends all astronomy, ancient, medieval 

 and modem. Nevertheless to see the proofs as St. Thomas saw 

 them, it is necessary to accept, at least historically, the system 

 of the universe as he understood it. 



There can scarcely be any doubt that St. Thomas' first proof 

 is derived historically from Aristotle's Physics and Meta- 

 physics. This is clearly evident in the detailed analysis pre- 

 sented in Summa contra gentiles, I, c. 13, where Aristotle is 

 explicitly cited as intending to prove the existence of God ex 

 parte motus duabus viis. The first way is a paraphrase of 

 Phys. VII, c. 1 to VIII, c. 5, text. 35; the second corresponds to 

 Phys. VIII, c. 5, text. 36, to the end. The first starts mth the 

 example of solar movement and ends disjunctively with Plato's 

 self-mover of the first sphere or Aristotle's separated mover of 

 the whole. The second starts with various types of self-movents, 

 showing how all must be reduced to some primum movens se 

 quod sit sempiternum, and ends with God as a self-movent. 

 " But since God is not a part of any self-movent, Aristotle in 

 his Metaphysics further discovers from this mover which is a 

 part of a self-movent, another mover entirely distinct, who is 

 God." Two objections to the Aristotelian argument are easily 

 handled. The first, that it assumes the eternity of motion con- 

 trary to the Catholic faith, is shown to be irrelevant, for it 

 makes no difference whether or not motion is eternal; there is 

 still need of an adequate mover. The second, that Aristotle 

 assumes the animation of celestial bodies contrary to the view 

 of many, is likewise shown to be irrelevant, for even if the celes- 

 tial bodies are animated, one must still conclude according to 

 Aristotle's principles to an unmoved mover entirely separated 

 from bodies. A simplified form of this manifestior via is the 

 only one presented by St. Thomas in his Compendium theo- 

 logiae for Brother Reginald of Pipemo. 



The involvement of celestial bodies in the other proofs for 

 God's existence is not so patent in the text of St. Thomas. 

 However, it ought to be obvious that the argument from effi- 



