It is impossible, then, that anything should be both mover and the thing moved, in regard to the same thing and in the same way, or that it should move itself. Everything, therefore, is moved by something else. If, then, that by which it is moved, is also moved, this must be moved by something still different, and this, again, by something else. But this process cannot go on to infinity because there would not be any first mover, nor, because of this fact, anything else in motion, as the succeeding things would not move except because of what is moved by the first mover, just as a stick is not moved except through what is moved from the hand. Therefore it is necessary to go back to some first mover, which is itself moved by nothing–and this all men know as God.
Briefly explain and then evaluate this proof for the existence of God.