Marsilio Ficino’s Platonic Theology, Volume I

32This is especially so because the principle of things must by its own power have existed and continue to exist eternally. It must always have existed, for it could not at some time have proceeded from itself, since it would then have existed before itself; nor could it have proceeded from another, since nothing is before the first. Other things, however, would never have existed unless the first had existed beforehand. It must also always continue to exist, since if the principle is extinguished, all things collapse, and neither it nor anything else can ever arise again. It must therefore possess infinite power, through which it lives infinitely from itself. It will not possess this power if it is corporeal. For if it has infinite dimensions, nothing else will exist among things besides it; if finite dimensions, it will also have finite power. I pass over what we shall show elsewhere: neither a body nor a corporeal form, needy and mutable as it is, can be a sufficient principle of motion, but everything corporeal is moved by another; and an artisan who is mingled with and tainted by the thing made cannot rule the work, nor be a perfect artisan or the first architect of the world's fabric.

33Let us therefore transcend corporeal form and now consider the first form that next presents itself. Just as from body, as the lowest thing, we ascended to corporeal form as an intermediate—because it possesses something of body insofar as it is spread through body, yet does not possess something else of body, since it is not itself a composite of matter and form—so now let us advance from this intermediate to a higher, namely incorporeal, form, which possesses nothing of body and distributes qualities to bodies. Since it subsists through itself, it is named true form and essence—the third essence, I say—which in its proper place we shall also call the rational soul, accompanied by the irrational soul as a shadow accompanies a body. That essence is judged by the Platonists to be both true and immortal because it does not need parts into which it might someday be dissolved and through which its dispersed power might be weakened; it is not bound to a subject whose loss might cause it someday to vanish; it is not mixed with a contrary form by which it might be corrupted; and, because of the indivisible simplicity of its substance, which remains in itself, it is neither enclosed by place nor subject to time or motion.