namely, that the movements of the celestial spheres have existed from eternity. This can be true only if an infinite succession of temporally originated things is possible. If such a succession is impossible, the movement of the celestial sphere must have a beginning. If, however, an infinite succession of temporally originated things is possible, this does not establish the eternity of anything in the world, since the coming into being of the celestial spheres may depend upon temporally originated things preceding them, and so on indefinitely.
If you say, “This entails a succession of temporally originated things subsisting in that which is eternal,” there are several responses:
First: This is your own position; you do not consider it impossible. In your view, the celestial sphere is eternal and without beginning, even though it is a body in which temporally originated things subsist.
Second: If those temporally originated things cannot subsist in the Necessary Existent, they may subsist in one temporally originated thing after another. If this succession of temporally originated things can proceed from the eternal Necessary Existent, your argument is invalidated. If it cannot, both your position and your argument are invalidated, for you maintain that the succession of temporally originated events in the celestial spheres proceeds from that which is eternal and without beginning.
Third: We are discussing the matter on the assumption that an infinite succession of temporally originated things is possible. On this assumption, one of two alternatives must be accepted: either temporally originated things subsist in the Necessary Existent, or an infinite succession of temporally originated things proceeds from Him without anything temporally originated subsisting in Him.
Fourth: It may be said that temporally originated things subsisting in that which is eternal is either impossible or possible. If it is impossible, the celestial spheres must have come into being, which is what we seek to establish. If it is possible, this argument is invalidated.