Plotinos: Complete Works, v. 3 / In Chronological Order, Grouped in Four Periods

by Plotinus

Besides, this movement is a definite quantity. Either this quantity will be measured by the extension of the space traversed, and the interval will consist in that extension; but that extension is space, and not time. Or we shall say that movement has a certain interval because it is continuous, and that instead of stopping immediately it always becomes prolonged; but this continuity is nothing else than the magnitude (that is, the duration) of the movement. Even though after consideration of a movement it be estimated as great, as might be said of a "great heat"—this does not yet furnish anything in which time might appear and manifest; we have here only a sequence of movements which succeed one another like waves, and only the observed interval between them; now the sequence of movements forms a number, such as two or three; and the interval is an extension. Thus the magnitude of the movement will be a number, say, such as ten; or an interval that manifests in the extension traversed by the movement. Now the notion of time is not revealed herein, but we find only a quantity that is produced within time. Otherwise, time, instead of being everywhere, will exist only in the movement as an attribute in a substrate, which amounts to saying that time is movement; for the interval (of the movement) is not outside of movement, and is only a non-instantaneous movement. If then time be a non-instantaneous movement, just as we often say that some particular instantaneous fact occurs within time, we shall be forced to ask the difference between what is and what is not instantaneous. Do these things differ in relation to time? Then the persisting movement and its interval are not time, but within time.

POLEMIC AGAINST STRATO: TIME IS NOT MOTION AND REST.

Somebody might object that time is indeed the interval of movement, but that it is not the characteristic interval of movement itself, being only the interval in which movement exerts its extension, following along with it. All these terms lack definition. This (extension) is nothing else than the time within which the movement occurs. But that is precisely the question at issue, from the very start. It is as if a person who had been asked to define time should answer "time is the interval of the movement produced within time." What then is this interval called time, when considered outside of the interval characteristic of movement? If the interval characteristic of time be made to consist in movement, where shall the duration of rest be posited? Indeed, for one object to be in motion implies that another (corresponding object) is at rest; now the time of these objects is the same, though for one it be the time of movement, and for the other the time of rest (as thought Strato[451]). What then is the nature of this interval? It cannot be an interval of space, since space is exterior (to the movements that occur within it).

POLEMIC AGAINST ARISTOTLE: TIME IS NOT THE NUMBER AND MEASURE OF MOVEMENT.

8. (9). Let us now examine in what sense it may be said (by Aristotle[452]) that time is the number and measure of movement, which definition seems more reasonable, because of the continuity of movement. To begin with, following the method adopted with the definition of time as "the interval of movement," we might ask whether time be the measure and number of any kind of movement.[453] For how indeed could we give a numerical valuation of unequal or irregular movement. What system of numbering or measurement shall we use for this? If the same measure be applied to slow or to swift movement, in their case measure and number will be the same as the number ten applied equally to horses and oxen; and further, such measure might also be applied to dry and wet substances. If time be a measure of this kind, we clearly see that it is the measure of movements, but we do not discover what it may be in itself. If the number ten can be conceived as a number, after making abstraction of the horses it served to measure, if therefore a measure possess its own individuality, even while no longer measuring anything, the case must be similar with time, inasmuch as it is a measure. If then time be a number in itself, in what does it differ from the number ten, or from any other number composed of unities? As it is a continuous measure, and as it is a quantity, it might, for instance, turn out to be something like a foot-rule. It would then be a magnitude, as, for instance, a line, which follows the movement; but how will this line be able to measure what it follows? Why would it measure one thing rather than another? It seems more reasonable to consider this measure, not as the measure of every kind of movement, but only as the measure of the movement it follows.[452] Then that measure is continuous, so far as the movement it follows itself continue to exist. In this case, we should not consider measure as something exterior, and separated from movement, but as united to the measured movement. What then will measure? Is it the movement that will be measured, and the extension that will measure it? Which of these two things will time be? Will it be the measuring movement, or the measuring extension? Time will be either the movement measured by extension, or the measuring extension; or some third thing which makes use of extension, as one makes use of a foot-rule, to measure the quantity of movement. But in all these cases, we must, as has already been noticed, suppose that movement is uniform; for unless the movement be uniform, one and universal, the theory that movement is a measure of any kind whatever will become almost impossible. If time be "measured movement," that is, measured by quantity—besides granting that it at all needs to be measured—movement must not be measured by itself, but by something different. On the other hand, if movement have a measure different from itself, and if, consequently, we need a continuous measure to measure it, the result would be that extension itself would need measure, so that movement, being measured, may have a quantity which is determined by that of the thing according to which it is measured. Consequently, under this hypothesis, time would be the number of the extension which follows movement, and not extension itself which follows movement.

NOR CAN TIME BE A NUMBERED NUMBER (AS ARISTOTLE CLAIMED[452]).

What is this number? Is it composed of unities? How does it measure? That would still have to be explained. Now let us suppose that we had discovered how it measures; we would still not have discovered the time that measures, but a time that was such or such an amount. Now that is not the same thing as time; there is a difference between time and some particular quantity of time. Before asserting that time has such or such a quantity, we have to discover the nature of that which has that quantity. We may grant that time is the number which measures movement, while remaining exterior thereto, as "ten" is in "ten horses" without being conceived with them (as Aristotle claimed, that it was not a numbering, but a numbered number). But in this case, we still have to discover the nature of this number that, before numbering, is what it is, as would be "ten" considered in itself.[454] It may be said that it is that number which, by following number, measures according to the priority and posteriority of that movement.[452] Nor do we yet perceive the nature of that number which measures by priority and posteriority. In any case, whatever measures by priority or posteriority, or by a present moment,[455] or by anything else, certainly does measure according to time. Thus this number (?) which measures movement according to priority or posteriority, must touch time, and, to measure movement, be related thereto. Prior and posterior necessarily designate either different parts of space, as for instance the beginning of a stadium, or parts of time. What is called priority is time that ends with the present; what is called posteriority, is the time that begins at the present. Time therefore is something different from the number that measures movement according to priority or posteriority,—I do not say, any kind of movement, but still regular movement. Besides, why should we have time by applying number either to what measures, or to what is measured? For in this case these two may be identical. If movement exist along with the priority and posteriority which relate thereto, why will we not have time without number? This would amount to saying that extension has such a quantity only in case of the existence of somebody who recognizes that it possesses that quantity. Since (Aristotle[456]) says that time is infinite, and that it is such effectually, how can it contain number without our taking a portion of time to measure it? From that would result that time existed before it was measured. But why could time not exist before the existence of a soul to measure it? (Aristotle) might have answered that it was begotten by the soul. The mere fact that the soul measures time need not necessarily imply that the soul produced the time; time, along with its suitable quantity, would exist even if nobody measured it. If however it be said that it is the soul that makes use of extension to measure time, we will answer that this is of no importance to determine the notion of time.

POLEMIC AGAINST EPICURUS: TIME IS NOT AN ACCIDENT OR CONSEQUENCE OF MOVEMENT.

9. (10). When (Epicurus[457]) says that time is a consequence of movement, he is not explaining the nature of time; this would demand a preliminary definition of the consequence of movement. Besides, this alleged consequence of movement—granting the possibility of such a consequence—must be prior, simultaneous, or posterior. For, in whatever way we conceive of it, it is within time. Consequently, if the consequence of movement be time, the result would be that time is a consequence of movement in time (which is nonsense).