Marsilio Ficino’s Platonic Theology, Volume II

2Yet the creator of forms, with a view to the determinate end and completeness of the work of the world, brings forms into being with this distinction: he naturally determines each to a definite mode of being, some to be in a body and others to be in themselves without matter. A form impressed upon matter does not properly exist and has no being of its own. Rather, it is called that by which the composite itself exists, and it exists through the common being of the whole. If being belongs to form in its own right, then surely, because a form in a body is itself form, being must likewise belong to it in its own right. But how can this be, when it depends upon matter and is contained under the being of the composite whole? Attend closely. Being belongs to it in its own right—that is, being follows it through itself. It follows through itself, I say, according to the form's own nature. For what else does ‘through itself’ mean but ‘through its own nature’? Its nature is such as its maker assigned to it, and its maker ordained that it should inhere in matter. Its own nature, therefore, is to inhere in matter. Through this nature being follows it. Being thus follows it through itself, but follows it, I say, as inhering in matter; in a certain sense it belongs to the form to be implanted in matter before it belongs to it to exist. It therefore exists only so long as it inheres in matter. It does not inhere forever, because matter, prepared for every form, often gives place to contrary forms that drive out the earlier ones. It therefore does not exist forever. But a form determined by the creator to a mode of being in which it subsists in itself apart from body has, because it too is form, the further property that being belongs to it in its own right—that is, through its own nature. The nature assigned to it is to adhere to itself. Its being therefore follows it insofar as it adheres to itself; that is, its existence follows it without springing from a subject. Whenever you say that being follows it through itself, you are saying that being follows it as it adheres to itself. Yet nothing departs from itself. For what could fall between a thing and its very self and separate it from itself? If it exists insofar as it adheres to itself, then because it always so adheres, it also always exists. The soul is a form of this kind. It is therefore immortal.