Marsilio Ficino’s Platonic Theology, Volume I

2This becomes clear again from the following. A bodily condition produced by qualities cannot remain entirely the same and unchanged for any span of time; it is always altered both into one proportion of degrees and then another, and for better or worse. Suppose someone were to say that a fully developed bodily condition had endured for an hour. When the hour was over, the Platonists would ask him whether the power in that condition was then equal to what it had been at the hour's beginning. If the power was not equal, the condition certainly did not stand unchanged for the hour, since during that hour it was altered in its potency. If an equal power is said to remain in it, the condition will endure for another hour. Equal powers produce equal effects. Hence, if through so great a power it remained for one hour, through an equal power it will remain for another. When the second hour is complete, they will again ask whether that power is equal or unequal. If unequal, the condition did not stand; if equal, it will stand for just as long again. Proceeding in the same way without end, they will show that this bodily nature, if it has stood for even an hour or half an hour, will remain forever. Yet no bodily constitution considered in itself endures forever, since all such constitutions are soon extinguished and perish. Thus the same constitutions scarcely persist for a moment. And because they begin and end in the same instant, while in beginning and ending they do not possess the fullest state of existence, and because a complete act of existing is required for acting, this appears to confirm what we proved in the preceding discussion: qualities do not contain a sufficient principle of action.

3But to return to the question proposed here: if, so far as qualities themselves are concerned, there is in them a motion devoid of every kind of stability, how can they be generated immediately by a cause so far removed from them that it possesses a state wholly free of motion? If everything passes from one extreme to another through intermediates—as from winter through spring into summer, and from summer through autumn into winter—then between wholly mobile quality and wholly immobile essence there must necessarily be something that is partly immobile and partly mobile. The substance that is the immediate begetter of qualities therefore cannot be altogether immobile.