Commentary Aristotle Physics
Lecture 6. The definition of place
It will now be plain from these considerations what place is. There are just four things of which place must be one: the form, or the matter, or some sort of extension between the bounding surfaces of the containing body, or this boundary itself if it contains no extension over and above the bulk of the body that comes to be in it.
Three of these it obviously cannot be.
The form is supposed to be place because it surrounds, for the extremities of what contains and of what is contained are coincident.
Both the form and the place, it is true, are boundaries, but not of the same thing: the form is the boundary of the thing, while the place is the boundary of the body that contains it.
The extension between the extremities is thought to be something, because what is contained and separate may often be changed while the container remains the same (as water may be poured from a vessel)—the assumption being that the extension is something over and above the body displaced.
But there is no such extension. One of the bodies that change places and are naturally capable of being in contact with the container falls in whichever it may chance to be.
If there were an extension that were such as to exist independently and be permanent, there would be an infinity of places in the same thing.
For when the water and the air change places, all the portions of the two together will play the same part in the whole that was previously played by all the water in the vessel.
At the same time, the place too will be undergoing change, such that there will be another place that is the place of the place, and many places will be coincident.
There is not a different place of the part, in which it is moved, when the whole vessel changes its place, but it is always the same.
For it is in the place where they are that the air and the water (or the parts of the water) succeed each other, not in that place in which they come to be, which is part of the place that is the place of the whole heavens.
The matter, too, might seem to be place, at least if we consider it in what is at rest and is thus separate but in continuity. For just as in change of quality there is something that was formerly black and is now white, or formerly soft and now hard—this is just why we say that the matter exists—so place, because it presents a similar phenomenon, is thought to exist, but in the one case, we say so because what is now water was previously air, while in the other because where water is now, there was air previously.
But the matter, as we said before, is neither separable from the thing nor contains it, while place has both characteristics.
Well, then, if place is none of the three—neither the form nor the matter nor an extension that is always there, different from and over and above the extension of the thing that is displaced—place necessarily is the one of the four which is left, namely, the boundary of the containing body at which it is in contact with the contained body. (By “the contained body” is meant what can be moved by way of locomotion.)
Place is thought to be something important and hard to grasp, both because the matter and the form present themselves along with it and because the displacement of the body that is moved takes place in a stationary container, for it seems possible that there should be an interval that is other than the bodies that are moved.
The air, which is thought to be incorporeal, also contributes something to the belief: it is not only the boundaries of the vessel that seem to be place, but also what is between them, regarded as empty.
In fact, just as the vessel is a transportable place, so place is a non-portable vessel. So, when what is within a thing that is moved is moved and changes its place, like a boat on a river, what contains plays the part of a vessel rather than that of place.
Place, on the other hand, is rather what wants to be immobile, so it is rather the whole river that is place, for as a whole, it is immobile.
Hence, we conclude that the immobile boundary of that which contains first is place.
This explains why the middle of the heavens and the boundary of circular change of place as to us is seen as “up” and “down” in the strict and fullest sense for all men. For the one is always at rest, while the inner side of the rotating body remains in the same way.
Hence, since the light is what is naturally carried up, and the heavy what is carried down, the boundary that contains in the direction of the middle of the universe and the middle itself are down, and that which contains in the direction of the outermost part of the universe and the outermost part itself are up.
For this reason, too, place is thought to be a kind of surface and, as it were, a vessel, that is, a container of the thing.
Further, place is coincident with the thing, for boundaries are coincident with the bounded.
455. After setting out the preliminary notions required for the search of the definition of place, the Philosopher now begins his search for the definition.
About this, he does three things:
first, he looks into each part of the definition;
second, he concludes the definition, at “hence, we conclude” (212a20; [470]);
third, he shows that “it is a good definition, at this explains why” (212a21; [471]).
As to the first, he does two things:
first, he searches for the genus of place;
second, for the differentia that will complete the definition, at “place is thought to be” (212a7; [467]).
In searching for the genus of place, he divides.
In connection with this, he does three things:
first, he gives the division;
second, he excludes three members of the division, at “three of these” (211b9; [457]);
third, he argues for the fourth member, at “well, then, if place” (212a2; [466]).
456. He says first (211b5) that, from the previous discussion, the nature of place may already be clear. For it seems that, according to what is ordinarily said of place, it is one of four things: matter, or form, or the space between and within the boundaries of the container; or, if there is no space within the boundaries of the container that has its own dimensions over and above the dimensions of the body existing within the confines of the container, then it will be necessary to posit a fourth possibility, namely, that place is the boundary of the containing body.
457. Then, at “three of these” (211b9), he excludes three members of this division.
First, he proposes what he intends, saying that it is clear from what follows that place is not any of these three.
Second, he pursues his intention, at “the form is supposed” (211b10; [458]).
And he says, first, that it is not form;
second, that it is not space, at “the extension between” (211b14; [460]);
third, that it is not matter, at “the matter, too” (211b29; [464]).
458. In regard to the first, he does two things.
First (211b10), he sets down why form seems to be place: it is because form is a container, and this seems to be a property of place.
Now, the boundaries of the containing body and those of the contained are together, since the container and the contained are contiguous.
Thus, it does not seem that the containing boundary, which is place, is separate from that of the body contained. Consequently, there does not seem to be any difference between place and form.
459. Second, at “both the form and the place” (211b12), he shows that form is not place. For although place and form are alike in that each is a kind of boundary, nevertheless they are not the boundary of one and the same thing: form is the boundary of the body of which it is the form, while place is not a boundary of the body of which it is the place, but of the body containing it. So, although the boundaries of the container and of the contained are together, they are not identical.