  Maimonides offers several proofs for the existence of God, all of which are versions of the cosmological argument (GP 2.1). Rather than begin with a definition of God and try to show that God’s essence implies existence, he begins with a description of the world as we know it and tries to show that it implies the existence of God. According to one such argument, we assume that the heavenly bodies are engaged in eternal motion. We then recognize that it is impossible for there to be an infinite body or an infinite number of finite bodies. So every corporeal thing is finite. If it is finite, it can only contain a finite amount of power. If it can only contain a finite amount of power, it can only explain motion over a finite period of time. Because the heavenly bodies are always moving, the only thing that can explain that motion is an infinite power. Because an infinite power cannot be contained in a finite thing, it cannot be corporeal. If it is not corporeal, it is not subject to division or change. Seeing that its power is infinite, it cannot derive that power from something else. Thus the only way to explain the motion of the heavenly bodies is to posit the existence of a being that is neither a body nor a force in a body.