Enneads III.7: Of Time and Eternity
Time Is Not Begotten by Movement, but Only Indicated Thereby
Indeed, as it was not possible to determine the time itself of the Soul, and to measure within themselves the parts of an invisible and uncognizable duration, especially for men who did not know how to count, the (world) Soul created day and night so that their succession might be the basis of counting as far as two, by the aid of this variety. Plato[464] indicates that as the source of the notion of number. Later, observing the space of time which elapses from one dawn to another, we were able to discover an interval of time determined by an uniform movement, so far as we direct our gaze thereupon, and as we use it as a measure by which to measure time. The expression "to measure time" is premeditated, because time, considered in itself, is not a measure. How indeed could time measure, and what would time, while measuring, say? Would time say of anything, "Here is an extension as large as myself?" What indeed could be the nature of the entity that would speak of "myself"? Would it be that according to which quantity is measured? In this case, time would have to be something by itself, to measure without itself being a measure. The movement of the universe is measured according to time, but it is not the nature of time to be the measure of movement; it is such only accidentally; it indicates the quantity of movement, because it is prior to it, and differs from it. On the other hand, in the case of a movement produced within a determinate time, and if a number be added thereto frequently enough, we succeed in reaching the knowledge of how much time has elapsed. It is therefore correct to say that the movement of the revolution operated by the universal Sphere measures time so far as possible, by its quantity indicating the corresponding quantity of time, since it can neither be grasped nor conceived otherwise. Thus what is measured, that is, what is indicated by the revolution of the universal Sphere, is time. It is not begotten, but only indicated by movement.
MOVEMENT IS SAID TO BE MEASURED BY SPACE, BECAUSE OF ITS INDETERMINATION.
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 easier 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.