Commentary Aristotle Physics
Lecture 5. Preliminaries to the definition of place
What, then, after all is place? The answer to this question may be elucidated as follows. Let us take for granted about it the various characteristics that are supposed correctly to belong to it essentially.
We assume, then, this maxim: place is what contains that of which it is the place. Place is no part of the thing. The primary place of a thing is neither less nor greater than the thing. Place can be left behind by the thing and is separable. In addition, all place admits of the distinction of up and down, and each of the bodies is naturally carried to its appropriate place and rests there, and this makes the place either up or down. Having laid these foundations, we must complete the theory.
We ought to try to make our investigation such as will render an account of place and will not only solve the difficulties connected with it but also show that the attributes supposed to belong to it do really belong to it, and further will make clear the cause of the trouble and of the difficulties about it. Such is the most satisfactory kind of exposition.
First, then, we must understand that place would not have been thought of if there had not been a special kind of motion, namely, that with respect to place. It is chiefly for this reason that we suppose the heaven also to be in place, because it is in constant motion.
Of this kind of change, there are two species—locomotion, on the one hand, and increase and diminution, on the other. For these too involve variation of place: what was then in this place has now in turn changed to what is larger or smaller.
Again, when we say a thing is moved, the predicate belongs to it either actually, in virtue of its own nature, or in virtue of something conjoined with it.
In the latter case, it may be either something that, by its own nature, is capable of being moved, such as the parts of the body or the nail in the ship, or something that is not in itself capable of being moved but is always moved through its conjunction with something else, like “whiteness” or “science.” These have changed their place only because the subjects to which they belong do so.
We say that a thing is “in the world” in the sense of in place because it is in the air and the air is in the world. And, when we say it is in the air, we do not mean it is in every part of the air, but that it is in the air because of the outer surface of the air which surrounds it, for if all the air were its place, the place of a thing would not be equal to the thing—which it is supposed to be, and which the primary place in which a thing is actually is.
When what surrounds [a thing], then, is not separate from the thing, but is in continuity with it, the thing is said to be in what surrounds it not in the sense of in place, but as a part in a whole.
But, when the thing is separate and in contact, it is immediately “in” the inner surface of the surrounding body, and this surface is neither a part of what is in it nor yet greater than its extension, but equal to it; for the extremities of things that touch are coincident.
Further, if one body is in continuity with another, it is not moved in that, but with that. On the other hand, it is moved in that if it is separate. It makes no difference whether what contains is moved or not.
Again, when it is not separate, it is described as a part in a whole, as the pupil in the eye or the hand in the body; when it is separate, [it is] as the water in the barrel or the wine in the cup. For the hand is moved with the body and the water in the barrel.
445. After setting forth a preliminary discussion about whether place exists and what it is, and after solving some doubtful points on these matters, the Philosopher now begins the task of determining the truth about place.
First, he gives some presuppositions to be used in determining about place;
second, he shows what qualities a definition of place should have, at “we ought to try” (211a7; [447]);
third, he begins to determine about place at, first, then, we must (211a12; [448]).
446. He says first, therefore (210b32), that it will be clear from the following just what place is. But we must first adopt, as it were, certain suppositions and self-evident principles, namely, those that appear intrinsic to place.
Indeed, there are four of these. First, all agree on this maxim: place contains that of which it is the place, yet in such a way that place is not any part of the thing in place. He says this to exclude the containing force of form, which is part of a thing but contains in a manner different from place.
The second supposition is that the primary place, that in which something exists primarily, is equal to the thing in place, neither greater nor less than it.
The third supposition is that a place exists for everything in a place—that is, everything in place has a place, but not in the sense that one and the same place is never lost by one and the same thing capable of being in a place. For a place can be separated from a thing in place. However, when one place is lost by a thing in place, it acquires another place.
The fourth supposition is that, in all places, there is found, as a difference of place, an “up” and a “down,” and that each body, when it is outside its proper place, naturally seeks it, and when it is in it, naturally remains there. Now, the proper places of natural bodies are “up” and “down,” to which they are naturally borne and in which they remain. But he says this in keeping with the opinion of those who posited no body other than the four elements, for he has not yet proved the heavenly body to be neither light nor heavy—which he will prove later, in De caelo 1.3. From these presuppositions, he proceeds to the consideration of what remains.
447. Then, at “we ought to try” (211a7), he shows what qualities should be found in a definition of place. And he says that, in defining place, our attention should be focused on four things that indeed are necessary for a perfect definition.
The first is that one show what place is, for a definition is an expression indicating what a thing is.
Second, one must resolve conflicting arguments about place, for the knowledge of truth involves the solution of doubts.
Third, the given definition should reveal the properties of place that inhere in it, because a definition is the middle term in a demonstration, by which the proper accidents are demonstrated of the subject.
Fourth, it should be clear why there is disagreement about place and of all the conflicting things said about it. Such a procedure is the most beautiful way of defining anything.
448. Then, at “first, then, we must” (211a12), he determines about place;
first, he shows what place is;
second, he settles the doubts previously mentioned, at “it is clear, too” (212b22; [487]);
third, he assigns the cause of the natural properties of place, at “also, it is reasonable” (212b29; [492]).
About the first, he does two things:
first, he shows what place is;
second, how something exists in place, at “if, then, a body” (212a31; [473]).
As to the first, he does two things:
first, he mentions some facts preliminary to his hunt for the definition;
second, he begins to investigate the definition of place, at “it will now be plain” (211b5; [455]).
449. In regard to the first, he makes four preliminary statements.
The first is that the question of place would never have arisen were there no motion in regard to place. For it was necessary to posit place as something distinct from the object in place, because two bodies are found successively in the same place, and in like manner, one body successively in two places. (Similarly, it was the successive change of forms in one and the same matter that led to the knowledge of matter). For this reason, some are convinced that the heavens are in place, since they are always in motion. Now, of motions, one is according to place per se—namely, the change of place—and another is consequently related to place, namely, increase and decline, for as a body grows or decreases, it acquires a larger or a smaller place.
450. He gives the second reason at “again, when we say” (211a17), saying that some things are moved per se in act, as is the case with every body, while others are moved according to accident.
This latter can occur in two ways. For some things that could be moved per se are in fact moved accidentally, such as when the parts of a body are moved per accidens while they are in the whole body, but when they are separated, they are moved per se. Thus, a nail, when it is embedded in a ship, is moved per accidens, but when it is extracted, it is moved per se.
Other things are not able to be moved per se, but only per accidens, as is the case with whiteness and knowledge, which change place when that in which they are changes place. This point was brought up because things are apt to be in place per se or per accidens, actually or potentially, in the same way as they are apt to be moved in those ways.
451. He gives the third reason at “we say that a thing” (211a23), when he says that someone is said to be in the heavens as in a place because he is in the air, which indeed is in the heavens.
Yet we do not say that anyone is in the entire air primarily and per se, but he is said to be in the air by reason of the ultimate boundary of the air containing him.
For if the whole air were anything’s place, such as a man’s, the place and the thing in the place would not be equal—which is against what was supposed above. But that in which something exists primarily is seen to be the boundary of the containing body, and this is what primary place is supposed to be, namely, equal.
452. He gives the fourth reason at “when what surrounds” (211a29).
First, he mentions it;
second, he proves it, at “further, if one body” (211a34; [453]).
He says first that, whenever the container is not separate from the thing contained but is continuous with it, the latter is not said to be in it as in a place, but as a part in a whole, such as when we say that one part of the air is contained by the totality of air.
And he concludes this from what went before, for where there is a continuum, there is no ultimate boundary in act—something that is required for place, as was stated above.
But, when the container is separated and contiguous to the thing contained, this latter is in place and exists in the ultimate boundary of the container primarily and per se—of a container that is not a part of the contained and neither greater nor less in dimension, but equal. But how the container and the thing contained can be equal he shows by pointing out that the ultimate boundaries of things touching are together: hence, their ultimate boundaries must be equal.
453. Then, at “further, if one body” (211a34), he proves the fourth point by two arguments.
The first of these is that something contained that forms a continuum with the container is not moved in the container, but with the container, as the part is moved simultaneously with the whole. But, when it is separate from the container, then it can be moved in it, whether the container be moved or not—for a man is moved on a ship whether it be moving or at rest. Therefore, since something can be moved in a place, it follows that place is a separated container.
454. He gives a second argument for the fourth point at “again, when it is not separate” (211b1), saying that, when the thing contained is not separate from the container but continuous with it, then it is said to be in it as a part in a whole, as sight is in the eye as a formal part and the hand in the body as an organic part.
But, when the container and the thing contained are separate, then the latter is in it as in a vessel, like water in a barrel or wine in a cup. The difference between the example in the first case and that in the second is that the hand is moved with the body, but not in the body, but the water is moved in the barrel. Therefore, since we have said above that to be in place is to be there as in a vessel but not as a part in a whole, it follows that place is like a separated container.