Marsilio Ficino’s Platonic Theology, Volume II

Ninth argument: a body does not move itself.

1Whatever is truly and primarily self-moving—so that one and the same thing is wholly both the source and the receptacle of motion—must be self-moving throughout itself. This is evident in all other things that are said to be such in themselves and primarily: what is clear in this way is clear throughout itself; what is good in this way is wholly good; what is understood in this way is wholly intelligible. For an essence that first pours forth some quality, and first embraces and receives it, performs both offices perfectly and brings both about throughout itself.

2There must, however, be found somewhere in nature an essence self-moving or moved from itself in just this way; and the soul is such an essence, as we showed in the preceding books. But even if body is supposed to be self-moving in the primary sense, it still cannot be so throughout itself. For every part of it would have to be moved by itself, as would the parts and particles of those parts. If there were a single particle in the body that did not move itself, the body would not be moved from itself throughout. It would therefore not be truly and primarily self-moving, but would be so through the participation and presence of some other thing that is such primarily. Hence, for the body to be perfectly self-moving, every one of its particles would have to be moved by itself. Those particles are divisible to infinity, and thus the particles that move themselves will be innumerable. What moves acts, and what acts exists in actuality. There will therefore be infinitely many parts actively moving themselves, and infinitely many movers in every body in the world.