Then he said:

“Every state—that is, an accident—that cannot conceivably remain constant is motion. Anything that did not exist for a time and then came into being is temporally originated. Whenever something temporally originated comes into being, something upon which it depends is itself temporally originated, for a temporally originated thing cannot bring about its own existence: every contingent thing requires a determining factor. Now, if its determining factor were everlasting, together with everything contributing to that determination, the thing itself would be everlasting and would therefore not be temporally originated. Since it is temporally originated, however, something upon which it depends must itself be temporally originated.

“The same argument applies in turn to that thing, so an infinite regress is unavoidable. Yet an infinite series whose members exist simultaneously is impossible. There must therefore be an infinite series whose members do not coexist and which never breaks off. Otherwise, the same argument would apply to the first temporally originated thing after the interruption. Thus there must be continual, uninterrupted origination and renewal in existence. What necessarily undergoes renewal by virtue of its essence is motion.”

He went on to complete the argument that perpetual motion must continue and that this is the motion of the celestial spheres.

[Refutation of his argument from several perspectives. The first perspective]

His argument may be refuted from several perspectives.

The first perspective

Several answers may be given to him on this point: