VIII. In the next place, it must be considered how time is the number or measure of motion; for it is better to assert this of it, on account of its continuity. In the first place, therefore, here also it may be doubted, whether it is similarly the number or measure of every motion, in the same manner as it was dubious respecting the interval of motion. For how can any one numerate inordinate and anomalous motion, or what number or measure will there be of it, or according to what will the measure subsist ? But if he numerates and measures with the same thing, both irregular and regular motion, whether swift or slow, the number and the measure will be a thing of such a kind, as if it were the decad, measuring both horses and oxen, or as if the same thing were the measure both of moist and dry substances. If, therefore, time is a measure of this kind, it has indeed been shown what the things are of which time is the measure, viz. that it is the measure of motions, but it has not yet been shown what time is. If, however, in the same manner as the decad when assumed without horses, may be understood as number, and a measure is a measure possessing a certain proper nature, though it should not yet measure any thing, thus also it is necessary time should subsist, being a measure; — if therefore time is such a thing in itself as number, in what will it differ from this number which subsists according to the decad, or from any other monadic number ? But if it is a continued measure, being a certain quantity, it will be such a measure as a certain cubital magnitude. It will, therefore, be magnitude, such as a line accompanied with motion. But how, since it also runs, can it measure that with which it runs in conjunction? For why should one measure rather than the other ? And it is better and more probable to admit this not in every motion, but in that with which it concurs. This, however, ought to be continuous, so far as the concurrent motion is successive. But that which measures ought not to be considered as subsisting externally, nor as separate, but as at once measured motion. And what will that be which measures ? Will the motion indeed be measured, but the magnitude be that which measures ? And which of these will time be ? Will it be the measured motion, or the magnitude which measures ? For time will either be the motion which is measured by magnitude, or magnitude which measures, or that which uses magnitude, as a cubit for the purpose of measuring the quantity of the motion. In all these, however, it is more probable as we have said to suppose that the motion is equable. For without equability, and besides this, without one motion of the universe, the doubt will be greater than that which results from admitting that time is in some way or other the measure of motion. But if time is measured motion, and is measured by quantity, then just as if it Avere necessary that motion should be measured, it would not be requisite that it should be measured by itself, but by something else, thus also it is necessary, if motion has another measure besides itself, and on this account we are in want of a continuous measure, for the purpose of measuring it, that magnitude itself should have a measure, in order that the motion may be as much in quantity as its measure. And thus time will be the number of the magnitude attending the motion, and not the magnitude which runs in conjunction with the motion.
It is necessary, however, to doubt what this number is, whether it is monadic, and how it measures ? For though some one should discover how it measures, yet he would not find time measuring, hut a certain quantity of time. This, however, is not the same with time (simply considered). For it is one thing to speak of time, and another, of so much time. For prior to the so much, it is necessary to say what that is which is so much. Is time, therefore, the number which measures motion externally ? Such as the decad in horses, and not that which is assumed together with horses. What this number, therefore, is, has not been shown, which prior to measuring, is what it is, in the same manner as the decad. Shall we say it is that number which measures by running according to the prior and posterior of motion ?1 But it is not yet manifest what this number is which measures according to prior and posterior. That, however, which measures according to prior and posterior, whether by a point, or by any thing else, entirely measures according to time. This number, therefore, which measures motion by prior and posterior, will be successive to, and in contact with time, in order that it may measure it. For prior and posterior, must either be assumed locally, as the beginning (and end) of a stadium, or temporally. For in short, with respect to prior and posterior, the former indeed is time ending in the now; but the latter is time beginning from the now. Time, therefore, is different from the number which measures motion according to prior and posterior, not only motion of any kind, but also that which is orderly. In the next place, why when number is adjoined, whether according to the measured, or the measuring, (for the same number may be both that which measures, and is measured) — why therefore when number is added, will there be time; but motion existing, and prior and posterior entirely subsisting about it, there will not be time ? Just as if some one should say that magnitude is not as great as it is, unless some one apprehends what the quantity of it is. Since time, however, is, and is said to be infinite, how will there be number about it, unless a part of it being selected is measured, in which case it will happen that it exists prior to its being measured. But why will not time be prior to the existence of soul that measures it ? Unless it should be said that the generation of it is effected by soul; since it is by no means necessary that time should exist because it is measured by soul. For it would exist as much as it is iD quantity, though no one should measure it. -And if some one should say that it is soul which uses magnitude for the purpose of measuring time, what will this have to do with the conception of time ?
Time is defined by Aristotle, to be the number of motion according to prior and posterior, which accords with Plato’s definition of it in the ” Timaeus,” viz. that it is an eternal image flowing according to number. For this shows that time subsists according to number which has the relation of an image, and exists according to the order of motion, i.e. according to prior and posterior. In short, time is properly the measure of motion according to the flux of being, which is the peculiarity of generation, or becoming to be. ↩