The Start of Motion

Was there ever a becoming of motion before which it had no being, and is it perishing again so as to leave nothing in motion?

Or are we to say that it never had any becoming and is not perishing, but always was and always will be?

Is it in fact an immortal never-failing property of things that are, a sort of life as it were to all naturally constituted things?

The existence of motion is asserted by all who have studied nature. Such people study:

• the construction of the world
• the process of becoming and perishing
  • These could not come about without motion.

Some say that there is an infinite number of worlds:

• some are in process of becoming
• others are in process of perishing

Those who believe so assert that there is always motion since these processes of becoming and perishing of the worlds necessarily involve motion.

Whereas those who hold that there is only one world, whether everlasting or not, make corresponding assumptions in regard to motion.

If then it is possible that at any time nothing should be in motion, this must come about in one of 2 ways:

1. In the way of Anaxagoras

He says that:

• all things were together and at rest for an infinite period of time
• then Mind introduced motion and separated them

2. In the way of Empedocles

He says that the universe is alternately in motion and at rest.

It is:

• in motion when Love is making the one out of many, or Strife is making many out of one
• at rest in the intermediate periods of time

Since One hath learned to spring from Manifold, And One disjoined makes manifold arise, Thus they Become, nor stable is their life: But since their motion must alternate be, Thus have they ever Rest upon their round

Anaxagoras

He means that they alternate from the one motion to the other.

How does this matter stand?

I say motion is the fulfilment of the movable in so far as it is movable.

Each kind of motion, therefore, involves things that are capable of that motion.

In fact, common people admit that a thing can be in a type of motion if that things is capable of that motion.

Thus, a thing:

• can be changed if it is capable of that change
• can be in locomotion if it is capable of local change

And so, there must be:

• something capable of being burned before there can be a process of being burned,
• something capable of burning before there can be a process of burning

These things also must either:

• have a beginning before which they had no being, or
• be eternal.

If there was a becoming of every movable thing, then before that motion another motion must have happened to cause that motion.

It is unreasonable to suppose, on the other hand, that these things were in being throughout all previous time without any motion.

For if we are to say that, while there are on the one hand things that are movable, and on the other hand things that are motive, there is a time when there is a first movent and a first moved, and another time when there is no such thing but only something that is at rest.

Then this thing at rest must previously have been in process of change. For there must have been some cause of its rest, rest being the privation of motion.

Therefore, before this first change there will be a previous change.

Some things cause motion in only one way.

Others can produce either of 2 contrary motions.

Thus, fire causes heating but not cooling, whereas it would seem that knowledge may be directed to two contrary ends while remaining one and the same.

Even in the former class, however, there seems to be something similar, for a cold thing in a sense causes heating by turning away and retiring, just as one possessed of knowledge voluntarily makes an error when he uses his knowledge in the reverse way.

But at any rate all things that are capable respectively of affecting and being affected, or of causing motion and being moved, are capable of it not under all conditions, but only when they are in a particular condition and approach one another: so it is on the approach of one thing to another that the one causes motion and the other is moved, and when they are present under such conditions as rendered the one motive and the other movable.

So if the motion was not always in process, it is clear that they must have been in a condition not such as to render them capable respectively of being moved and of causing motion, and one or other of them must have been in process of change: for in what is relative this is a necessary consequence: e.g. if one thing is double another when before it was not so, one or other of them, if not both, must have been in process of change.

It follows then, that there will be a process of change previous to the first.

Further, how can there be any ‘before’ and ‘after’ without the existence of time? Or how can there be any time without the existence of motion? If, then, time is the number of motion or itself a kind of motion, it follows that, if there is always time, motion must also be eternal. But so far as time is concerned we see that all with one exception are in agreement in saying that it is uncreated: in fact, it is just this that enables Democritus to show that all things cannot have had a becoming: for time, he says, is uncreated. Plato alone asserts the creation of time, saying that it had a becoming together with the universe, the universe according to him having had a becoming.

Since time cannot exist and is unthinkable apart from the moment, and the moment a kind of middle-point, uniting as it does in itself both a beginning and an end, a beginning of future time and an end of past time, it follows that there must always be time: for the extremity of the last period of time that we take must be found in some moment, since time contains no point of contact for us except the moment. Therefore, since the moment is both a beginning and an end, there must always be time on both sides of it. But if this is true of time, it is evident that it must also be true of motion, time being a kind of affection of motion.

The same reasoning will also serve to show the imperishability of motion: just as a becoming of motion would involve, as we saw, the existence of a process of change previous to the first, in the same way a perishing of motion would involve the existence of a process of change subsequent to the last: for when a thing ceases to be moved, it does not therefore at the same time cease to be movable-e.g. the cessation of the process of being burned does not involve the cessation of the capacity of being burned, since a thing may be capable of being burned without being in process of being burned-nor, when a thing ceases to be movent, does it therefore at the same time cease to a be motive. Again, the destructive agent will have to be destroyed, after what it destroys has been destroyed, and then that which has the capacity of destroying it will have to be destroyed afterwards, (so that there will be a process of change subsequent to the last,) for being destroyed also is a kind of change. If, then, view which we are criticizing involves these impossible consequences, it is clear that motion is eternal and cannot have existed at one time and not at another: in fact such a view can hardly be described as anythling else than fantastic.

And much the same may be said of the view that such is the ordinance of nature and that this must be regarded as a principle, as would seem to be the view of Empedocles when he says that the constitution of the world is of necessity such that Love and Strife alternately predominate and cause motion, while in the intermediate period of time there is a state of rest.

Probably also those who like like Anaxagoras, assert a single principle (of motion) would hold this view. But that which is produced or directed by nature can never be anything disorderly: for nature is everywhere the cause of order.

Moreover, there is no ratio in the relation of the infinite to the infinite, whereas order always means ratio. But if we say that there is first a state of rest for an infinite time, and then motion is started at some moment, and that the fact that it is this rather than a previous moment is of no importance, and involves no order, then we can no longer say that it is nature’s work: for if anything is of a certain character naturally, it either is so invariably and is not sometimes of this and sometimes of another character (e.g. fire, which travels upwards naturally, does not sometimes do so and sometimes not) or there is a ratio in the variation.

It would be better, therefore, to say with Empedocles and any one else who may have maintained such a theory as his that the universe is alternately at rest and in motion: for in a system of this kind we have at once a certain order.

But even here the holder of the theory ought not only to assert the fact: he ought to explain the cause of it: i.e. he should not make any mere assumption or lay down any gratuitous axiom, but should employ either inductive or demonstrative reasoning.

The Love and Strife postulated by Empedocles are not in themselves causes of the fact in question, nor is it of the essence of either that it should be so, the essential function of the former being to unite, of the latter to separate.

If he is to go on to explain this alternate predominance, he should adduce cases where such a state of things exists, as he points to the fact that among mankind we have something that unites men, namely Love, while on the other hand enemies avoid one another: thus from the observed fact that this occurs in certain cases comes the assumption that it occurs also in the universe.

Then, again, some argument is needed to explain why the predominance of each of the two forces lasts for an equal period of time.

But it is a wrong assumption to suppose universally that we have an adequate first principle in virtue of the fact that something always is so or always happens so.

Thus Democritus reduces the causes that explain nature to the fact that things happened in the past in the same way as they happen now.

But he does not think fit to seek for a first principle to explain this ‘always’.

So, while his theory is right in so far as it is applied to certain individual cases, he is wrong in making it of universal application.

Thus, a triangle always has its angles equal to 2 right angles.

But this has an ulterior cause of the eternity of this truth. Whereas first principles are eternal and have no ulterior cause.

So I conclude that:

• there always has been motion
• there never will be a time when there will be no motion