Summary: Physics (page 4)
Book IV
What is the place?
The main movement is that which occurs according to place: transport.
There are six directions: up, down, left, right, front, back.
It is here that Aristotle sets out his famous theory of the natural place, according to which every body has a place in which it naturally stands:
If nothing stands in the way, each moves towards its own place, one above, the other below 1.
What does place consist of? A body mass? That is impossible, otherwise two bodies would be in the same place
. The paradox of place is that it cannot belong to corporeal things or incorporeal things, it has indeed a magnitude but no body
2.
Aristotle distinguishes the common place (that in which all bodies are found) from the particular place (that in which they are first found).
He defines place as the primary container of that of which it is the place
3.
He solves Zeno's aporia (the locus must itself be in a locus, which leads to an absurd regress to infinity) by showing that the locus can be found in a body as health is in warm bodies as a state, and warmth in the body as a property
4.
Since motion occurs within a container that remains at rest (the place), the first immobile limit of the container, that is what the place is
5.
Thus the place is somewhere, not as in a place, but as the limit is in the limited
6.
The void is a kind of place in which there is nothing (a pure place).
For Aristotle, the void does not exist. Proponents of the void try to prove its existence by showing that without it, no movement would be possible. It is quite the opposite for Aristotle: Not a single thing can be in motion if the vacuum exists; indeed in the vacuum there is necessarily rest, for there is nothing towards which a motion will more or less willingly move, since, as a vacuum, it possesses no difference
7.
Moreover a movement that occurs in a vacuum would be infinite, since there is nothing to stop it.
The vacuum exists neither in act, nor even in potential.
Aristotle now examines the notion of time.
He expounds the famous paradox of time: time does not exist since it is composed of the past, which is no more, the future, which is not yet, and the present, which is evanescent, and disappears all the time.
Time is not movement, since movement can be more or less rapid, unlike time. However, time does not exist without change: no time seems to have passed when we keep the same thought. Thus, we say that time has passed when we perceive a change.
Thus time is neither movement nor without movement
8. It is therefore necessarily something of movement
9. What exactly? Here is the answer:
When we perceive the anterior and posterior, then we say there is time, for this is what time is: the number of motion according to the anterior and posterior 10.
Thus, since time is the measure of movement
11, time is number
12.
It is impossible for time to exist if the soul does not exist, since number cannot exist without that which is number.
1 Book IV, 208b
2 ibid., 209a
3 ibid.,
4 ibid., 210b
5 ibid., 212a
6 ibid., 212b
7 ibid., 214b
8 ibid., 219a
9 ibid.
10 ibid., 219b
11 ibid., 221a
12 ibid.