Marsilio Ficino’s Platonic Theology, Volume II

Eighth argument. A bodily constitution acts through the power of its qualities.

1Every operation of a bodily constitution and of its form is carried out through the qualities of which that constitution is composed. Thus a constitution never performs anything so lofty that the powers of its qualities do not extend to that result. The work of heat is to penetrate and dissolve. The soul's nutritive power, however, uses heat as an instrument not merely to dissolve food—which is heat's own proper work—but also to cook and digest it and bring it to the form of living flesh and the human figure. This action exceeds the power of heat. Nor can an animal's growth proceed from heat as its principal cause. Growth occurs only through nourishment; and since it is brought to a definite limit of size and a definite figure, whereas heat, given matter, spreads without definite limit or figure, and since the principal agent must prescribe the limit and figure of its work, it is clear that heat cannot be the principal craftsman of growth. Indeed, no other accidental form can do this if heat, the most excellent of them all, cannot. Yet growth is brought about by the soul. From this we conclude that the soul is not an accidental form—a conclusion we must prove repeatedly. We also conclude that it is not constituted from accidental forms, for it could not rationally order qualities that wander without definite limit, degree, proportion, or figure toward those very determinations. Finally, we conclude that the soul is not some substantial form of an element or a mixture. The motion of a form of this kind is directed toward a single limit, as we have said, whereas growth extends equally in every direction.