12 



they exist in perfection when they are generated 

 and receive their proper nature. Hence matter 

 [or a universal recipient] is necessary to the exist- 

 ence of generation. 



The second thing which is necessary, is the ex- 

 istence of contrarieties, in order that mutations and 

 changes in quality may be effected, matter for this 

 purpose receiving passive qualities, and an aptitude 

 to the participation of forms. Contrariety is also 

 necessary, in order that powers, which are natu- 

 rally mutually repugnant, may not finally vanquish, 

 or be vanquished by, each other. But these powers 

 are the hot and the cold, the dry and the moist. 



Essences rank in the third place ; and these are 

 fire and water, air and earth, of which the hot and 

 the cold, the dry and the moist, are powers. But 

 essences differ from powers ; for essences are locally 

 corrupted by each other, but powers are neither 

 corrupted nor generated, for the reasons [or forms] 

 of them are incorporeal. 



Of these four powers, however, the hot and the 

 cold subsist as causes and things of an effective 

 nature, but the dry and the moist rank as matter 

 and things that are passive* ; but matter is the first 



* Thus also Aristotle, in his Treatise on Generation and Cor- 

 ruption, Stgftov 3i xui v/'f^ov, xeci uygav, TO. p.iv ru vrowrixo, tivui, ret 

 2i vw ffufanxa Xiyirui. i. e. " With respect to heat and cold, dry. 

 ness and moisture, the two former of these are said to be effective, 

 but the two latter passive powers." 



