166 JAMES A. WEISHEIPL 



Christian God. But the approach is different in metaphysics. 

 Since the term of terrestrial movement and alteration is 'per se 

 the generation of a substantial being/^ and since the substantial 

 being of the very heavens must be produced, beyond the physi- 

 cal universe there must exist a pmicipium universi esse, who is 

 the efficient source of being, the formal principle of all being, 

 and the universal end of all things.*'' Hence it belongs to both 

 physics and metaphysics to consider celestial phenomena and 

 God, but physics considers these through the principles of 

 motion {secundum pnncipia motus) , while metaphysics con- 

 siders these through the principles of being (essendi) . In other 

 words, the natural philosopher arrives at the existence of God 

 as the first mover, but the metaphysician arrives at His exist- 

 ence as the efficient cause, the formal principle and the ultimate 

 end of all being. 



This does not mean, Albert points out, that the metaphysi- 

 cian gives the propter quid reason for changeable substance, and 

 the physicist the quia, as some would have it. " For if the 

 physicist borrowed from the metaphysician, it would follow 

 that physics is subalternated to first philosophy, which from the 

 opening pages of this science we have shown to be false." *'' 

 Thus physics and metaphysics are each autonomous sciences 

 with special principles of investigation proper to each. How- 

 ever, unless it is first demonstrated in physics that there exists 

 some real separated substance, there is no need for the sub- 

 sequent investigation called metaphysics. The Platonists, 

 Albert repeatedly points out, postulated ideas and mathe- 

 matical entities separate from matter in order to explain 

 sensible being; but these cannot exist apart from matter, and 

 if they did, they could not be responsible for motion in the 

 universe.*^ Therefore if some separated substance exists to be 

 studied in metaphysics, this substance can be demonstrated 



is 



46 



St. Albert, Lib. VIII Pkys., tr. II, c. 4, ed. cit.. Ill, 572a. 



St. Albert, Lib. XI Metaph., tr. I, c. 3, ed. cit., VI, 584b-585a. 

 " Ibid. 



" St. Albert, Lib. XI Metaph., tr. I, cc. 4 & 8; lib. 1, tr. V, cc. 8, 12 & 14; lib. 

 VII, tr. II, c. 3, et alibi. 



