Ocellus Lucanus, Firmicus Maternus, Select Theorems of Proclus (Thomas Taylor)

they exist in perfection when they are generated and receive their proper nature. Hence, matter [or a universal recipient] is necessary for the existence of generation.

The second thing which is necessary is the existence of contrarieties, so that mutations and changes in quality may be effected, with matter receiving passive qualities and an aptitude for the participation of forms. Contrariety is also necessary so that powers which are naturally opposed to one another may not finally vanquish, or be vanquished by, each other. These powers are the hot and the cold, and the dry and the moist.

Essences rank in the third place; these are fire, water, air, and earth, of which the hot, cold, dry, and moist are the powers. But essences differ from powers; for essences are locally corrupted by each other, but powers are neither corrupted nor generated, because their underlying principles [or forms] are incorporeal.

Of these four powers, 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 Corruption: "With respect to heat and cold, dryness and moisture, the two former are said to be effective, but the two latter are said to be passive powers."