The measure of movement, therefore, seems to be what is measured by a definite movement, but which is other than this movement. There is a difference, indeed, between that which is measured, and that which measures; but that which is measured is measured only by accident. That would amount to saying that what is measured by a foot-rule is an extension, without defining what extension in itself is. In the same way, because of the inability to define movement more clearly because of its indeterminate nature, we say that movement is that which is measured by space; for, by observation of the space traversed by movement, we can judge of the quantity of the movement.
TIME IS MEASURED BY MOVEMENT, AND IN THAT SENSE IT IS THE MEASURE OF MOVEMENT.
12. (13). The revolution of the universal Sphere leads us therefore to the recognition of time, within which it occurs. Not only is time that in which (all things "become," that is, grow), but time has to be what it is even before all things, being that within which everything moves, or rests with order and uniformity. This is discovered and manifested to our intelligence, but not produced by regular movement and rest, especially by movement. Better than rest, indeed, does movement lead us to a conception of time, and it is either to appreciate the duration of movement than that of rest. That is what led philosophers to define time as the measure "of" movement, instead of saying, what probably lay within their intention, that time is measured "by" movement. Above all, we must not consider that definition as adequate, adding to it that which the measured entity is in itself, not limiting ourselves to express what applies to it only incidentally. Neither did we ever discern that such was their meaning, and we were unable to understand their teachings as they evidently posited the measure in the measured entity. No doubt that which hindered us from understanding them was that they were addressing their teachings to learned (thinkers), or well prepared listeners, and therefore, in their writings, they failed to explain the nature of time considered in itself, whether it be measure or something measured.
PLATO DOES MAKE SOME STATEMENTS THAT ALLOW OF BEING JUSTIFIED.
Plato himself, indeed, does say, not that the nature of time is to be a measure or something measured, but that to make it known there is, in the circular movement of the universe, a very short element (the interval of a day), whose object is to demonstrate the smallest portion of time, through which we are enabled to discover the nature and quantity of time. In order to indicate to us its nature ("being"), (Plato[438]) says that it was born with the heavens, and that it is the mobile image of eternity. Time is mobile because it has no more permanence than the life of the universal Soul, because it passes on and flows away therewith; it is born with the heavens, because it is one and the same life that simultaneously produces the heavens and time. If, granting its possibility, the life of the Soul were reduced to the unity (of the Intelligence), there would be an immediate cessation of time, which exists only in this life, and the heavens, which exist only through this life.
TIME AS THE PRIOR AND POSTERIOR OF THE MOVEMENT OF THIS LIFE WOULD BE ABSURD.
The theory that time is the priority and posteriority of this (earthly) movement, and of this inferior life, is ridiculous in that it would imply on one hand that (the priority and posteriority of this sense-life) are something; and on the other, refusing to recognize as something real a truer movement, which includes both priority and posteriority. It would, indeed, amount to attributing to an inanimate movement the privilege of containing within itself priority with posteriority, that is, time; while refusing it to the movement (of the Soul), whose movement of the universal Sphere is no more than an image. Still it is from the movement (of the Soul) that originally emanated priority and posteriority, because this movement is efficient by itself. By producing all its actualizations it begets succession, and, at the same time that it begets succession, it produces the passing from one actualization to another.
THE PRIMARY MOVEMENT OF INTELLIGENCE THE INFORMING POWER OF TIME.
(Some objector might ask) why we reduce the movement of the universe to the movement of the containing Soul, and admit that she is within time, while we exclude from time the (universal) Soul's movement, which subsists within her, and perpetually passes from one actualization to another? The reason is that above the activity of the Soul there exists nothing but eternity, which shares neither her movement nor her extension. Thus the primary movement (of Intelligence) finds its goal in time, begets it, and by its activity informs its duration.