It follows, therefore, that they move spontaneously by their own sense and divinity.
Aristotle also deserves high commendation for his observation that everything that moves is either put in motion by natural impulse, or by some external force, or of its own accord; and that the sun, and moon, and all the stars move; but that those things which are moved by natural impulse are either borne downward by their weight, or upward by their lightness; neither of which things could be the case with the stars, because they move in a regular circle and orbit.

Nor can it be said that there is some superior force which causes the stars to be moved in a manner contrary to nature.

For what superior force can there be?
It follows, therefore, that their motion must be voluntary.

And whoever is convinced of this must discover not only great ignorance, but great impiety likewise, if he denies the existence of the Gods; nor is the difference great whether a man denies their existence, or deprives them of all design and action; for whatever is wholly inactive seems to me not to exist at all.

Their existence, therefore, appears so plain that I can scarcely think that man in his senses who denies it.
XVII.