Lecture 22 — All motion and change are in time

But it is the nature of all change to alter things from their former condition. In time, all things come into being and pass away, for which reason some called it the wisest of all things, but the Pythagorean Paron called it the most stupid, because in it we also forget; and his was the truer view.

It is clear, then, that it must be in itself, as we said before, the cause of destruction rather than of coming into being (for change, in itself, makes things depart from their former condition), and only accidentally of coming into being, and of being.

A sufficient evidence of this is that nothing comes into being without itself moving somehow and acting, but a thing can be destroyed even if it does not move at all.

And this is what, as a rule, we chiefly mean by a thing’s being destroyed by time. Still, time does not work even this change; even this sort of change takes place accidentally in time.

We have stated, then, that time exists and what it is, and in how many senses we speak of the “now,” and what “at some time,” “lately,” “presently” or “just,” “long ago,” and “suddenly” mean.

These distinctions having been drawn, it is evident that every change and everything that moves is in time, for the distinction of faster and slower exists in reference to all change, since it is found in every instance.

In the phrase “moving faster,” I refer to that which changes before another into the condition in question, when it moves over the same interval and with a regular motion, such as in the case of locomotion, if both things move along the circumference of a circle, or both along a straight line (and similarly in all other cases).

But what is before is in time, since we say “before” and “after” with reference to the distance from the “now” and the “now” is the boundary of the past and the future. And, since “nows” are in time, the before and the after will be in time too; for in that in which the “now” is, the distance from the “now” will also be. But “before” is used contrariwise with reference to past and to future time: in the past, we call “before” what is farther from the “now,” and “after” what is nearer, but in the future, we call the nearer “before” and the farther “after.” Thus, since the “before” is in time, and every motion involves a “before,” evidently every change and every motion is in time.

620. After comparing time and the now to things that exist in time, the Philosopher here explains some things that were touched upon above: (Lect. 20, nn. 561, 564.)

first, how corruption is attributed to time;

second, how every motion and change exist in time, at these distinctions (222b30; [623]).

Concerning the first, he does two things:

first, he makes his proposition clear by an argument;

second, by a sign, at a sufficient evidence (222b22; [622]).

621. He first says, therefore (222b16), that every change, by its definition, removes from its natural disposition the thing that is changed, but both generation and corruption take place in time. Therefore, some attributed generations in things to time, as in the case of learning and the like, saying that time is very wise because the generation of science takes place in time. But a certain philosopher by the name of Parus, a Pythagorean, claimed on the contrary that time was wholly unteachable, for with length of time comes forgetfulness. And he was more right, for as was said above, time per se is a cause more of corruption than of generation. (Lect. 20, n. 564.) The reason is that time is the number of motion and change is per se destructive and corruptive. It does not cause generation and existence except per accidens. For from the fact that something is moved, it departs from the state in which it was. But that it arrive at some disposition is not implied in the account of motion insofar as it is motion, but insofar as it is finished and perfect. And this perfection is brought about by motion on account of the intention of the agent that moves to a predetermined end. Therefore, corruption is attributed rather to change and time, whereas generation and being are attributed to the agent and generator.

622. Then, at a sufficient evidence (222b22), he explains the same point with a sign, and he says that a sufficient sign of his claim is that, while nothing is found to come into being independently of an agent and a mover, a thing can corrupt without a mover obviously moving it to corruption. And such corruption we are accustomed to attribute to time, as when someone fails through old age from a corrupting internal cause that is not apparent, but when someone is killed with a sword, his corruption is not attributed to time. However, in generation, the generator is always evident, because nothing is generated by itself. That is why generation is not attributed to time as corruption is. Nevertheless, corruption is not attributed to time in such a way as that time should cause it, but rather as occurring in time, while the corrupting influence is latent.

Finally, at we have stated, then (222b27), he asserts in a summary way that it has been explained that time exists, and what it is, and how “now” is used in various senses, and what are the meanings of “then” and “just” and “presently” and “long ago” and “suddenly.”

623. Then, at these distinctions (222b30), he shows by two arguments that all change occurs in time.

The first of these is that the distinction of faster and slower is found in every change. But these are determined by time, because that is said to be changed more quickly that is changed first to a designated term over the same distance, provided that both motions are subject to the same rule, such as in the case of local motion, if both motions are circular, or both in a straight line.

But, if one were along a circle and the other straight, the fact that one reached its terminus before the other would be no reason for saying that one moved more quickly than the other. And the same is to be understood of other types of change. It follows, therefore, that every change exists in time.

624. He then gives a second reason, at but what is before (223a4), but in this proof, he makes use of the proposition that before and after exist in time. He manifests this proposition in the following way. Before and after are said according to the distance from the now, which is the boundary of the past and of the future. Both nows exist in time; therefore, both before and after exist in time, because that in which the now is and that in which the distance from the now is must be the same; just as it is in the same thing that there are a point and the distance taken in relation to that point, for both are in a line. And, because he had said that before and after are determined by the distance to the now, he shows how this occurs in a contrary manner with the past and the future. For in the past, what is before is what is farther from the now, but what is after is nearer to the now, but in the future, it is just the opposite. If, therefore, before and after exist in time, and before and after follow upon every motion, then necessarily every motion exists in time.