Motion is not subject to beginning and end. For everything that comes into being after a state of non-existence requires motion to precede it, namely, the actualization from non-being. Hence if motion came into being, there was motion before motion, which is a contradiction. As motion and time go together, time also is eternal.

Again, the prime matter common to the four elements is not subject to genesis and decay. For all genesis is the combination of a pre-existing matter with a new form, namely, the form of the generated thing. If therefore the prime matter itself came into being, there must be a previous matter from which it came, and the thing that resulted must be endowed with form. But this is impossible, since the prime matter has no matter before it and is not endowed with form.

Among the proofs derived from the nature of God are the following:

If God brought forth the world from non-existence, then before he created it he was a creator potentially and then became a creator actually. There is then potentiality in the creator, and there must be a cause which changed him from a potential to an actual creator.

Again, an agent acts at a particular time and not at another because of reasons and circumstances preventing or inducing action. In God there are no accidents or hindrances. Hence he acts always.

Again, how is it possible that God was idle an eternity and only yesterday made the world? For thousands of years and thousands of worlds before this one are after all as yesterday in comparison with God's eternity.

These arguments Maimonides answers first by maintaining that Aristotle himself, as can be inferred from his manner, does not regard his discussions favoring the eternity of the world as scientific demonstrations. Besides, there is a fundamental flaw in Aristotle's entire attitude to the question of the ultimate principles and beginnings of things. All his arguments in favor of eternity of motion and of the world are based upon the erroneous assumption that the world as a whole must have come into being in the same way as its parts appear now after the world is here. According to this supposition it is easy to prove that motion must be eternal, that matter is not subject to genesis, and so on. Our contention is that at the beginning, when God created the world, there were not these laws; that he created matter out of nothing, and then made it the basis of all generation and destruction.

We can also answer the arguments in favor of eternity taken from the nature of God. The first is that God would be passing from potentiality to actuality if he made the world at a particular time and not before, and there would be need of a cause producing this passage. Our answer is that this applies only to material things but not to immaterial, which are always active whether they produce visible results or not. The term action is a homonym (cf. above, p. [240]), and the conditions applying to it in the ordinary usage do not hold when we speak of God.

Nor is the second argument conclusive. An agent whose will is determined by a purpose external to himself is subject to influences positive and negative, which now induce, now hinder his activity. A person desires to have a house and does not build it by reason of obstacles of various sorts. When these are removed, he builds the house. In the case of an agent whose will has no object external to itself this does not hold. If he does not act always, it is because it is the nature of will sometimes to will and sometimes not. Hence this does not argue change.[282]

So far our results have been negative. We have not proved that God did create the world in time; we have only taken the edge off the Aristotelian arguments and thereby shown that the doctrine of creation is not impossible. We must now proceed to show that there are positive reasons which make creation a more plausible theory than eternity.