2. A More Probable Proof of Both Ways

75. The first part [n.74] is proved easily, and that commonly according to both the theologians and the philosophers. For just as the moving second causes are sufficient to cause motion for all time from the beginning of the world to the judgment, so are they able to cause movement infinitely: for the virtue of the infinite mover [sc. God] is sufficient for causing motion of itself in its order as first cause, and the other virtues are, by virtue of the infinite mover, sufficient for causing motion sempiternally.

76. The possibility of the second part [sc. of the theologians, n.74] is proved, but not from what the philosophers concede but only from what the theologians concede, namely that the will of God is contingently disposed toward moving the heaven and not moving the heaven. When the first cause is contingently disposed to the effect, the effect is simply contingent, and the effect is able simply not to be from the fact that the [first] cause is simply able in its own order not to cause; and when it does not cause, nothing else will cause.

77. This [possibility of both parts] is proved in another way from the side of the movable itself, because the motion of the heaven is neither natural nor violent [sc. forced].

It is not natural, as Avicenna proves, Metaphysics 9 ch.2, first because, when it reached what it was naturally moved toward, it would naturally come to rest, because natural motion is toward natural rest in that toward which the motion is; and consequently motion away from that would be violent. And then further, since it is always the case that while there is approaching of one part [of the heaven] to some ‘where’, there is a receding of another part from that same ‘where’ (indeed, after any part has passed that ‘where’, it is, while it is approaching another ‘where’, receding from that [first] ‘where’ according to the diverse parts of the circle in which it is moved) - [since this is so] it follows that the same thing is moved naturally and violently at the same time.

78. Nor is the motion of the heaven violent, because then the receding from it would be natural, and then, as before, it would be natural and violent at the same time.

79. Therefore, on the part of the movable itself, there is no repugnance either to its motion being continued or to its motion coming to an end.