by Aristotle
A consideration of these points, then, gives adequate assurance of the truth of our contentions. The same could also be shown with the aid of the discussions which [10] fall under First Philosophy, as well as from the nature of the circular movement, which must be eternal both here and in the other worlds. It is plain, too, from the following considerations that the universe must be one.
The bodily elements are three, and therefore the places of the elements will be [15] three also; the place, first, of the body which sinks to the bottom, namely the region about the centre; the place, secondly, of the revolving body, namely the outermost place, and thirdly, the intermediate place, belonging to the intermediate body. Here in this third place will be the body which rises to the surface; since, if not here, it will be outside, and it cannot be outside: for we have two bodies, one weightless, one [20] endowed with weight, and below is the place of the body endowed with weight, since the region about the centre has been given to the heavy body. And its position cannot be unnatural to it; for it would have to be natural to something else, and there is nothing else. It must then occupy the intermediate place. What distinctions there are within the intermediate itself we will explain later on.
We have now said enough to make plain the character and number of the bodily elements, the place of each, and further, in general, how many in number the [25] various places are.
9 · We must show not only that the heaven is one, but also that more than one heaven is impossible, and, further, that, as exempt from decay and generation, the heaven is eternal. We may begin by rehearsing the puzzles. From one point of view it might seem impossible that the heaven should be one and unique, since in all [30] formations and products whether of nature or of art we can distinguish the shape in itself and the shape in combination with matter. For instance the form of the sphere is one thing and the gold or bronze sphere another; the shape of the circle again is [278a1] one thing, the bronze or wooden circle another. For when we state the essential nature of the sphere or circle we do not include in the formula gold or bronze, because they do not belong to its substance; but if we are speaking of the copper or gold sphere we do include them. We still make the distinction even if we cannot [5] conceive or apprehend any other example beside the particular thing. This may, of course, sometimes be the case: it might be, for instance, that only one circle could be found; yet none the less the difference will remain between being circle and being this particular circle, the one being form, the other form in matter, i.e. a particular thing. Now since the heaven is perceptible it must be regarded as a particular; for [10] everything that is perceptible subsists, as we know, in matter. But if it is a particular, there will be a distinction between being this heaven and being a heaven without qualification. There is a difference, then, between this heaven and a heaven without qualification; the second is form and shape, the first form in combination with matter; and any shape or form has, or may have, more than one particular [15] instance.
On the supposition of Forms such as some assert, this must be the case, and equally on the view that no such entity has a separate existence. For in every case in which the substance is in matter it is a fact of observation that the particulars of like form are several or infinite in number. Hence there either are, or may be, more [20] heavens than one. On these grounds, then, it might be inferred either that there are or that there might be several heavens. We must, however, return and ask how much of this argument is correct and how much not.
Now it is quite right to say that the formula of the shape apart from the matter must be different from that of the shape in the matter, and we may allow this to be true. We are not, however, therefore compelled to assert a plurality of worlds. Such [25] a plurality is in fact impossible if this world contains the entirety of matter, as in fact it does. But perhaps our contention can be made clearer in this way. Suppose aquilinity to be curvature in the nose or flesh, and flesh to be the matter of aquilinity. Suppose, further, that all flesh came together into a single whole of flesh [30] endowed with this aquiline quality. Then neither would there be, nor could there arise, any other thing that was aquiline. Similarly, suppose flesh and bones to be the matter of man, and suppose a man to be created of all flesh and all bones in indissoluble union. The possibility of another man would be removed. Whatever [278b1] case you took it would be the same. The general rule is this: a thing whose substance resides in a substratum of matter can never come into being in the absence of all matter. Now the heaven is certainly a particular and a material thing; if however it [5] is composed not of a part but of the whole of matter, then though being a heaven and being this heaven are still distinct, yet there is no other heaven, and no possibility of others being made, because all the matter is already included in this. It remains, then, only to prove that it is composed of all natural perceptible body.
[10] First, however, we must explain what we mean by ‘heaven’ and in how many ways we use the word, in order to make clearer the object of our inquiry. In one sense, then, we call ‘heaven’ the substance of the extreme circumference of the whole, or that natural body whose place is at the extreme circumference. We recognize habitually a special right to the name ‘heaven’ in the extremity or upper [15] region, which we take to be the seat of all that is divine. In another sense, we use this name for the body continuous with the extreme circumference, which contains the moon, the sun, and some of the stars; these we say are ‘in the heaven’.
In yet another sense we give the name to all body included within the extreme [20] circumference, since we habitually call the whole or totality ‘the heaven’. The word, then, is used in three senses.
Now the whole included within the extreme circumference must be composed of all physical and sensible body, because there neither is, nor can come into being, any body outside the heaven. For if there is a natural body outside the extreme [25] circumference it must be either a simple or a composite body, and its position must be either natural or unnatural. But it cannot be any of the simple bodies. For it has been shown that that which moves in a circle cannot change its place. And it cannot [30] be that which moves from the centre or that which lies lowest. Naturally they could not be there, since their proper places are elsewhere; and if these are there unnaturally, the exterior place will be natural to some other body, since a place which is unnatural to one body must be natural to another; but we saw that there is [279a1] no other body besides these. Then it is not possible that any simple body should be outside the heaven. But, if no simple body, neither can any mixed body be there; for the presence of the simple body is involved in the presence of the mixture. Further neither can any body come into that place; for it will do so either naturally or unnaturally, and will be either simple or composite; so that the same argument will [5] apply, since it makes no difference whether the question is ‘Is it there?’ or ‘Can it come to be there?’ From our arguments then it is evident not only that there is not, but also that there could never come to be, any bodily mass whatever outside the circumference. For the world as a whole includes all its appropriate matter, which is, as we saw, natural perceptible body. So that neither are there now, nor have there [10] ever been, nor can there ever be formed more heavens than one, but this heaven of ours is one and unique and complete.
It is therefore evident that there is also no place or void or time outside the heaven. For in every place body can be present; and void is said to be that in which the presence of body, though not actual, is possible; and time is the number of movement. But in the absence of natural body there is no movement, and outside [15] the heaven, as we have shown, body neither exists nor can come to exist. It is clear then that there is neither place, nor void, nor time, outside the heaven. Hence whatever is there, is of such a nature as not to occupy any place, nor does time age it; nor is there any change in any of the things which lie beyond the outermost motion; [20] they continue through their entire duration unalterable and unmodified, living the best and most self-sufficient of lives. As a m
atter of fact, this word ‘duration’ possessed a divine significance for the ancients; for the fulfilment which includes the period of life of any creature, outside of which no natural development can fall, has been called its duration. On the same principle the fulfilment of the whole [25] heaven, the fulfilment which includes all time and infinity, is duration—a name based upon the fact that it is always8—being immortal and divine. From it derive the being and life which other things, some more or less articulately but others feebly, enjoy. So, too, in its discussions concerning the divine, popular philosophy [30] often propounds the view that whatever is divine, whatever is primary and supreme, is necessarily unchangeable. This fact confirms what we have said. For there is nothing else stronger than it to move it—since that would be more divine—and it has no defect and lacks none of its proper excellences. Its unceasing movement, then, is also reasonable, since everything ceases to move when it comes to its proper [279b1] place, but the body whose path is the circle has one and the same place for starting-point and goal.
10 · Having established these distinctions, we may now proceed to the question whether the heaven is ungenerated or generated, indestructible or [5] destructible. Let us start with a review of the theories of other thinkers; for the proofs of a theory are difficulties for the contrary theory. Besides, those who have first heard the pleas of our adversaries will be more likely to credit the assertions which we are going to make. We shall be less open to the charge of procuring [10] judgement by default. To give a satisfactory decision as to the truth it is necessary to be rather an arbitrator than a party to the dispute.
That the world was generated all are agreed, but, generation over, some say that it is eternal, others say that it is destructible like any other natural formation. [15] Others again, with Empedocles of Acragas and Heraclitus of Ephesus, believe that it alternates, being sometimes as it is now and sometimes different and in a process of destruction, and that this continues without end.
Now to assert that it was generated and yet is eternal is to assert the impossible; for we cannot reasonably attribute to anything any characteristics but those which observation detects in many or all instances. But in this case the facts point the other way: generated things are seen always to be destroyed. Further, a [20] thing whose present state had no beginning and which could not have been other than it was at any previous moment throughout its entire duration, cannot possibly be changed. For there will have to be some cause of change, and if this had been present earlier it would have been possible for that which could not be otherwise to [25] be otherwise. Suppose that the world was formed out of elements which were formerly otherwise. Then if their condition was always so and could not have been otherwise, the world could never have come into being. And if the world did come into being, then, clearly, their condition must have been capable of change and not eternal: after combination therefore they will be dispersed, just as in the past after dispersion they came into combination, and this process either has been or could [30] have been, indefinitely repeated. But if this is so, the world cannot be indestructible, and it does not matter whether the change of condition has actually occurred or remains a possibility.
Some of those who hold that the world, though indestructible, was yet generated, try to support their case by a parallel which is illusory. They say that in their statements about its generation they are doing what geometricians do when they construct their figures, not implying that the universe really had a beginning, [280a1] but for didactic reasons facilitating understanding by exhibiting the object, like the figure, as in course of formation. The two cases, as we said, are not parallel; for, in the construction of the figure, when the various steps are completed the same figure forthwith results; but in these other demonstrations what results is not the same. [5] Indeed it cannot be so; for antecedent and consequent, as assumed, are in contradiction. The ordered, it is said, arose out of the unordered; and the same thing cannot be at the same time both ordered and unordered; there must be a process and a lapse of time separating the two states. In the figure, on the other hand, there is no [10] temporal separation. It is clear that the universe cannot be at once eternal and generated.
To say that the universe alternately combines and dissolves is no more paradoxical than to make it eternal but varying in shape. It is as if one were to think that there was now destruction and now existence when from a child a man is [15] generated, and from a man a child. For it is clear that when the elements come together the result is not a chance system and combination, but the very same as before—especially on the view of those who hold this theory, since they say that the [20] contrary is the cause of each state. So that if the totality of body, which is a continuum, is now in this order or disposition and now in that, and if the combination of the whole is a world or heaven, then it will not be the world that comes into being and is destroyed, but only its dispositions.
If the world is one, it is impossible that it should be, as a whole, first generated [25] and then destroyed, never to reappear; since before it came into being there was always present the combination prior to it, and that, we hold, could never change if it was never generated. If, on the other hand, the worlds are infinite in number the view is more plausible. But whether this is, or is not, impossible will be clear from what follows. For there are some who think it possible both for the ungenerated to be destroyed and for the generated to persist undestroyed. (This is held in the [30] Timaeus, where Plato says that the heaven, though it was generated, will none the less exist for the rest of time.) So far as the heaven is concerned we have answered this view with arguments appropriate to the nature of the heaven: on the general question we shall attain clearness when we examine the matter universally.
11 · We must first distinguish the senses in which we use the words [280b1] ‘ungenerated’ and ‘generated’, ‘destructible’ and ‘indestructible’. These have many uses, and though it may make no difference to the argument, yet some indeterminacy of thought must result from treating as indivisible something which is divided in many ways. The character which is the ground of the predication will always [5] remain obscure.
The word ‘ungenerated’ then is used in one sense whenever something now is, which formerly was not, no process of becoming or change being involved. Such is the case, according to some, with contact and motion, since there is no process of coming to be in contact or in motion.
It is used in another sense, when something which is capable of coming or of having come to be does not exist; such a thing is ungenerated in the sense that its [10] generation is a possibility. It is also applied where there is general impossibility of any generation such that the thing now is which then was not. (And ‘impossibility’ has two uses: first, where it is untrue to say that the thing can ever come into being, and secondly, where it cannot do so easily, quickly, or well.) In the same way the word ‘generated’ is used, first, where what formerly was not afterwards is, whether [15] a process of becoming was or was not involved, so long as that which then was not, now is; secondly, of anything capable of existing, ‘capable’ being defined with reference either to truth or to facility; thirdly, of anything to which the passage from not being to being belongs, whether already actual, if its existence is due to a process of becoming, or not yet actual but possible. The uses of the words ‘destructible’ and ‘indestructible’ are similar. ‘Destructible’ is applied to that which [20] formerly was and afterwards either is not or might not be, whether a period of being destroyed and changed intervenes or not; and sometimes we apply the word to that which a process of destruction may cause not to be; and also in a third sense, to that which is easily destructible, to the ‘easily-destroyed’, so to speak. Of the indestructible the same account holds good. It is either that which now is and now is [25] not, without any process of destruction, like contact, which without being destroyed afterwards is not, though formerly it was; or that which is but might not be, or which will at some time not be, though it now is. For you ex
ist now and so does the contact; yet both are destructible, because a time will come when it will not be true [30] of you that you exist, nor of these things that they are in contact. Thirdly in its most proper use, it is that which is, but is incapable of any destruction such that the thing which now is later ceases to be or might cease to be. And indestructible is also used of that which is destroyed with difficulty. [281a1]
This being so, we must ask what we mean by ‘possible’ and ‘impossible’. For in its most proper use the predicate ‘indestructible’ is given because it is impossible that the thing should be destroyed, i.e. exist at one time and not at another. And ‘ungenerated’ also involves impossibility when used for that which cannot be [5] generated, in such fashion that, while formerly it was not, later it is. An instance is a commensurable diagonal. Now when a thing can move or lift weights, we refer always to the maximum. We speak, for instance, of a power to lift a hundred talents or walk a hundred stades—though if it can effect the maximum it can also effect [10] any part of the maximum—since we feel obliged in defining the power to give the limit or maximum. A thing, then, which is capable of a certain amount as maximum must also be capable of that which lies within it. If, for example, a man can lift a hundred talents, he can also lift two, and if he can walk a hundred stades, he can [15] also walk two. But the power is of the maximum, and a thing said, with reference to its maximum, to be incapable of so much is also incapable of any greater amount. It is, for instance, clear that a person who cannot walk a thousand stades will also be unable to walk a thousand and one. This point need not trouble us, for we may take it as settled that what is, in the strict sense, possible is determined by a limiting [20] maximum. Now perhaps the objection might be raised that there is no necessity in this, since he who sees a stade need not see the measures contained in it, while, on the contrary, he who can see a dot or hear a small sound will perceive what is greater. This, however, does not touch our argument. The maximum may be [25] determined either in the power or in its object. The meaning of this is plain. Superior sight is sight of the smaller body, but superior speed is that of the greater body.