Whether however was motion once generated, not having a subsistence before, and will it again perish, so that nothing will be moved? or was it neither generated nor will be corrupted, but always was and always will be, and is this present with things as something immortal and unceasing, being as it were a certain life to all things which have a natural subsistence? That motion therefore is, all those assert who say any thing concerning nature, because they fabricate the world; and all these speculate concerning generation and corruption, which could not subsist unless motion had a being. Those too, who assert that there are infinite worlds, and that some of these worlds arc generated, and others corrupted, these say that motion always is: for it is necessary that the generations and corruptions of them should be accompanied with motion. But such as assert that there is one world, or that it is not always, these admit concerning motion what is conformable to that opinion. If therefore it be possible, that once nothing thing was moved, it is necessary that this must have happened in a twofold respect; for it must either be as Anaxagoras says, viz. that all things subsisting together, and being at rest in an infinite time, intellect produced, and separated, motion: or as Empedocles says, that things were alternately moved and at rest; being moved indeed, when friendship made one from many things, or strife many fromone; and at rest in the intervening times. For he says as follows:
As far as one from many was produc’d,
Or many to the one their being ow’d,
So far these natures generated were,
Nor firm eternity in them abides.
But so far as for ever they are chang’d,
Nor cease at once t’exist, for ever they
Immoveable, alternately remain.
For by the words, “so far as they are changed,” we must conceive that he means hitber and thither. With respect to these things therefore, we must consider how they subsist: for to perceive the truth respecting them, not only contributes to the contemplation concerning nature, but also to the method which pertains to the finJt principle. But we shall first begin from things which have been before defined by us in the Physics. We say, therefore, that motion is the perfect energy of that which is moveable, so far as it is moveable. Hence it is necessary that things should be present which are capable of being moved according to each motion. And without the definition of motion every one must acknowledge it to be necessary, that what is able to be moved, should be moved according to each motion; as for instance, that what is capable of being changed in quality, should be changed in quality, and that what can be locally changed, should be home along. Hence it is necessary that what is capable of being burnt, should be prior to that which is burnt; and that which has the power of burning, to that which burns. It is necessary, therefore, either that these should have been once generated, there being a time when they were not, or that they should be perpetual. If, however, each of those things which can move and be moved, is generated, it is necessary that another mutation and motion should be generated prior to the mutation which is assumed; according to which that is generated, which is able to be moved, or to move. But if they always had a prior subsistence, motion not existing; an absurdity will immediately appear to the intelligent. And to those who proceed still further, this will be found to happen by a yet greater necessity. For if, since some things are moveable, and others motive, there is at any time something which first moves, and something which is first moved; and if at another time there is nothing which moves, but it is at rest, it is necessary that this should have been previously changed: for there was some cause of its rest, since rest is a privation of motion. So that there will be a mutation prior to the first mutation; for some things move according to one motion, but others according to contrary motions. Thus fire heats indeed, but does not refrigerate; but science appears to be one of thiugs contrary. Hence there also something similar appears: for the cold heats being turned in a certain respect, and having departed; just as he who possesses scientific knowledge, willingly errs, when he improperly uses science. Such things, however, as are able to act and suffer, or to move and to be moved, are not entirely able to effect this, but then only, when they subsist in this manner, and are near to each other. Hence, when they approach near, the one moves, and the other is moved; and when they are so circumstanced, that the one is motive, and the other moveable. If, therefore, it was not always moved, it is evident that they were not so affected, as that the one could be moved, and the other could move; but it was necessary that one of them should be changed. For it is necessary that this should happen in things which have a relative subsistence. Thus, if a thing not having been double is now double, if not both, at least one of them mt1st hiive been changed. There will therefore be certain mutation prior to the first. To which may be added, ow will there be prior and posterior time not having a subsistence; or how will there be time motion not existing? But if time is the number of motion, or a certain motion; if time always is, it is necessary that motion also should be perpetual. Concerning time, however, all philosophers, except one, appear to accord, for they say that it is unbegotten. On this account Democritus shows, that it is impossible for all things to have been generated; because time is unbegotten. But Plato alone generates time; for he says, that it was generated together with the universe, and that the universe is generated. If, therefore, it is impossible for time to be, and to be conceived without the now but the now is a certain middle, possessing at the same time the beginning and the the end, the beginning indeed of the future time, and the end of the past; it is necessary that time should always be. For the extremity of the last time which is assumed will be in some now; since nothing can be assumed in time, besides the now. So that since the now is both a beginning and an end, it is necessary that time should always be, on each side of the now. But if time, it is evident that motion also must necessarily always exist; since time is a certain passion of motion. ‘I’he same reasoning likewise will prove, that motion is incorruptible. For as, if it be admitted that motion was generated, it will happen that there was a certain mutation prior to the first; so here it will happen that there is a mutation posterior to the last. For a thing will not at the same time cease to be moveable and to be moved: or to be capable of being burnt, and to be burnt (for that may be capable of being burnt, which is not burnt) nor to be motive and to move. But it will be requisite, that what is capable of being corrupted, should have been corrupted, when it is corrupted: and again afterwards, that which has the power of corrupting this. For corruption is a certain mutation. If, therefore, these things are impossible, it is evident that motion is perpetual, and not sometimes in existence, and sometimes not. For thus to speak rather resembles a fiction a fiction than any thing else; as also to assert, that it is thus naturally adapted, and that it is necessary to consider this as a principle, which Empedocles appears to have asserted, who says, that it is necessarily inherent in things, that friendship and strife should alternately govern and move, and that they should be at rest in the intermediate time. Perhaps also those who make one principle, as Anaxagoras, would assert the same thing. Nothing however among those things which consist from and according to nature, is deprived of order: for nature is to all things the cause of order. But the infinite has no ratio to the infinite; and all order is ratio. That any thing however should have been at rest for an infinite time, and afterwards should have been once moved; and that with respect to this there should be no difference, why it happened now rather than before, and again, that it should have no order, this is no longer the work of nature. For that which subsists by nature either subsists simply, and not diifere·nt)y at different times (as fire is naturally carried upwards, and not at one time and at another not), or it has a ratio which is not simple. Hence it is better to say with with Empedoclcs, and any other who may assert the same thing, that the universe is alternately at rest and in motion: for now a thing of this kind kind possesses a certain order. He however who asserts this, ought also to assign the cause of what he says, and not adopt any axiom without a reason, nor expect that it should be granted him; but he should either employ induction or demonstration. For the things which Empedocles supposes are not causes. Nor is this the essence of friendship or strife; but it is the province of the former to conjoin, and of the latter to separate. If also it is added, that they have dominion alternately, it should be shown in what particulars this happens; as for instance, because there is something which unites men, viz. friendship, and enemies avoid each other. For this is also supposed to be in the universe, because it thus appears to be in certain things. His assertion likewise, that this happens in equal times, requires a certain reason. And in short, to think that this is a sufficient principle, viz. that it either always is, or is always generated, this is not right; to which Democritus refers natural causes, because they were thus, and prior to this, generated. But he does not think that the principle of eternity should be investigated, in some things speaking rightly; but because he asserts this of all things, not rightly. For a triangle has always angles equal to two right, but at the same time there is a certain other cause of this perpetuity. Of principles, however, there is no other cause, since they are eternal. That there neither was therefore, nor will be a time, when motion was not, or will not be, has been thus far s
