13. None of the kinds of change mentioned in 4 is continuous except motion of translation; and of this only circular motion.
14. Motion of translation is the first by nature of the motions. For genesis and decay presuppose qualitative change; and qualitative change presupposes the approach of the agent causing the change to the thing undergoing the change. And there is no growth or diminution without antecedent genesis and decay.
15. Time is an accident following motion and connected with it. The one cannot exist without the other. No motion except in time, and time cannot be conceived except with motion. Whatever has no motion does not come under time.
16. Whatever is incorporeal cannot be subject to number, unless it is a corporeal power; in which case the individual powers are numbered with their matters or bearers. Hence the separate forms or Intelligences, which are neither bodies nor corporeal powers, cannot have the conception of number connected with them, except when they are related to one another as cause and effect.
17. Everything that moves, necessarily has a mover, either outside, like the hand moving the stone, or inside like the animal body, which consists of a mover, the soul, and a moved, the body proper. Every mobile of the last kind is called a self-moving thing. This means that the motor element in the thing is part of the whole thing in motion.
18. If anything passes from potentiality to actuality, the agent that caused this must be outside the thing. For if it were inside and there was no obstruction, the thing would never be potential, but always actual; and if there was an obstruction, which was removed, the agency which removed the obstruction is the cause which caused the thing to pass from potentiality to actuality.
19. Whatever has a cause for its existence is a "possible" existent in so far as itself is concerned. If the cause is there, the thing exists; if not, it does not. Possible here means not necessary.
20. Whatever is a necessary existent in itself, has no cause for its existence.
21. Every composite has the cause of its existence in the composition. Hence it is not in itself a necessary existent; for its existence is dependent upon the existence of its constituent parts and upon their composition.
22. All body is composed necessarily of two things, matter and form; and it necessarily has accidents, viz., quantity, figure, situation.