323 Hence, these motions are so far from being contraries, that they are actually only one, continuous, and having the same limit: and thus the effects that emanate from these causes must not be truly called contraries, since contrary effects depend on contrary causes: thus we cannot truly call an upward motion contrary to the following downward motion -- both of which motions emanate from a motion of the mixture of lightness and heaviness. And from this it can also easily be deduced how a state of rest does not intervene at the turning point.For, if there were then a rest, it would be necessary that a rest happen also in that motion of the mixture of heaviness and lightness, when the lightness had come into equality with the heaviness; for only then can the mobile be at rest, when the impelling force neither overcomes nor is overcome: but, as we have already made clear, that motion, when from light it becomes heavy, is one and continuous, as when hot becomes cold, which does not come to rest in time: hence also local motions, which emanate from that motion, will be one and continuous.But since this way of thinking runs against common opinion (it is commonly believed that there is a rest at the turning point), it will be deferred to the next chapter; there, the opposed way of thinking will first be examined and refuted, and our opinion will be rendered still stronger.
Older Works on Motion, Book II, chapter 7[323.19-328.10]In which it is demonstrated against Aristotle and the common way of thinking, that at the turning point no rest is given.
Aristotle and those who believe Aristotle believed that two contrary motions (he calls contraries those things that tend towards contrary limits) can in no way be continuous; and, for that reason, that when a stone is impelled upward and then comes back along the same line, at the turning point it is necessarily at rest. Now the most important argument, by which Aristotle tries to prove this {1}, is the following: That which {2} is moved by coming near a certain point and