Marsilio Ficino’s Platonic Theology, Volume II

2Yet when the author of all things begets the essences of forms and brings them into being, he determines some to a mode of being in which they exist in a body. The being of such an essence or form is thereby restricted by its agent to bodily conditions. When being is restricted to a body, the essence too is confined within the same limits. Natural bodies are conditioned to fill a place and to move through time. A form that in itself would have stood above determinate time and place therefore comes under a time and place of its own. Because it comes under time, it gradually begins, changes, and comes to an end. Because it comes under place, whenever the body in which it lies receives contrary qualities from day to day, the form too is disturbed by the storm of those qualities and becomes mortal. Such are the forms and qualities of bodies. Other essences of forms, however, the author brings into being in such a way that they obtain their own being not in some other thing or in matter, but contain it within themselves. Such are all forms alien to commerce with matter: they have their being in themselves, not in matter. Whatever is received by something is customarily received according to the receiver's capacity and drawn into its character. Now every essence is immortal in itself. Hence the being received by the essence becomes immortal, because it is received by an immortal thing in an immortal manner. A form separated from association with matter is therefore immortal in every respect—that is, both in its being and in its essence. Such is the third essence, the fountain of rational souls.