Marsilio Ficino’s Platonic Theology, Volume II

5Similarly, if the whole is said to move a part, it moves that one part through all the parts. Thus, in a certain way, it moves only that one part by itself. You see that in these two members of the division the whole can be said to move itself only through the part of it that moves itself, and not at all through the other parts. The whole, therefore, will not in truth be self-moving; perhaps only that part of the whole will be—and it will not even be a part of the whole if it performs something of itself. But if you grant the fourth possibility, that the whole is moved by the whole, then, since the whole may be nothing other than all the parts together, you will admit that all the parts are changed by all. In that case the composite should be said to move itself for no other reason than that every one of its parts moves itself.

6Accordingly, whenever you wish to affirm that a body is self-moving, you will be forced to take refuge in a part. We condemn this at the outset because the composite body will not be self-moving in the proper sense once it borrows that power from something else—namely, its parts. It is called self-moving by reason of its parts. Although that body may in some way be nothing other than all its parts together, it nevertheless seems to borrow this sort of motion from each of them, just as it receives its substance from each. Tell me, then, about the part or parts by reason of which the whole is asserted to move itself because they move themselves: are they indivisible? If they are, what moves itself is certainly not a body, but something indivisible within a body, by whose impulse the body too seems to be borne along of its own accord. If they are divisible, we shall divide them just as we have already divided the whole. By the same reasoning, we shall discover that they can in no way be said to move themselves except by reason of particles that move themselves.