[136] Our attitude is the same with respect to the inquiry about time. For if we depend on appearances, time seems to be something, but if we depend on the arguments about it, it appears unreal. Some ¹ define time as ‟the interval of the motion of the Whole” (meaning by ‟Whole” the Universe), others ² as ‟the actual motion of the Universe;” Aristotle (or, as some say, Plato) as ‟the number of the prior and posterior in motion;”

[137] Strato (or, as some say, Aristotle) as ‟the measure of motion and rest;” Epicurus (according to Demetrius the Laconian ³ ) as ‟a concurrence of concurrences, concomitant with days and nights and seasons and affections and non-affections and motions and rests.”

[138] And, in point of substance, some have affirmed that it is corporeal —for instance, Aenesidemus, arguing that it differs in nothing from Being and the prime body,—others, ⁴ that it is incorporeal. Either, then, all these theories are true, or all false, or some true and some false; but they cannot all be true (most of them being in conflict), nor will it be granted by the Dogmatists that all are false.

[139] And besides, should it be granted that the assertion of the corporeality of time is false, and that of its incorporeality likewise false, then, ipso facto, the unreality of time will be granted; for it cannot be anything but one or other of these. Nor yet can we apprehend which theories are true, which false, owing to the equal weight ⁵ of the rival opinions as well as the perplexity regarding the criterion and proof. ⁶

[140] Hence for these reasons we shall be unable to affirm anything positively about time.

Further, since time does not seem to subsist without motion or even rest, if motion is abolished, and likewise rest, time is abolished. None the less the following objections against time are made by some. If time exists, it is either limited or unlimited.

[141] But if it is limited, it began at a certain time and will end at a certain time. Consequently, there was once a time when time was not (before it began), and there will once be a time when time will not be (after it has ended); which is absurd. ⁷ So then time is not limited.

[142] But if it is unlimited, since part of it is said to be past, part present, and part future, the future and past are either existent or non-existent. But if they are non-existent, and there remains only the present, which is momentary, time will be limited and the original difficulties ⁸ will follow. And if the past exists and the future exists, each of these will be present. But it is absurd to call past and future time present; neither, then, is time unlimited. But if it is neither unlimited nor limited, time does not exist at all.

[143] Further, if time exists it is either divisible or indivisible. Now it is not indivisible; for it is divided, as they themselves declare, into present, past, and future. Yet it is not divisible either. For each divisible thing is measured by some part of itself, the measure coinciding with each part of the measured, as when we measure a cubit by a finger. But time cannot be measured by any part of itself. If, for instance, the present measures the past, it will coincide with the past and will therefore be past, and similarly it will be future in the case of the future. And if the future should measure the rest, it will be present and past, and so likewise the past will be future and present; which is nonsense. Neither, then, is time divisible. But if it is neither indivisible nor divisible, it does not exist.

[144] Time, too, is said to be tripartite, partly past, partly present, and partly future. Of these the past and the future are non-existent; for if past and future time exist now, each of them will be present. Neither is the present existent; for if present time exists it is either indivisible or divisible. Now it is not indivisible; for what changes is said to change in the present time, but nothing changes in indivisible time ⁹ —iron, for instance, into softness, and so on. Hence present time is not indivisible.

[145] Neither is it divisible; for it could not be divided into a plurality of presents, since time present is said to change into time past imperceptibly owing to the rapid flux of the things in the Universe. Nor yet into past and future; for so it will be unreal, having one part of itself no longer existent and the other part not yet existent.

[146] Hence, too, the present cannot be the end of the past and the beginning of the future, since then it will both be and not be existent; for it will exist as present, but will not exist because its parts are non-existent. Therefore it is not divisible either. But if the present is neither indivisible nor divisible, it does not exist. And when neither the present nor the past nor the future exists, time too is non-existent; for what is compounded of things unreal is unreal.

[147] This argument, too, is alleged against time: If time exists it is either generable and perishable or ingenerable and imperishable. ¹⁰ Now it is not ingenerable and imperishable, since part of it is said to be past and no longer in existence, and part to be future and not yet in existence. Neither is it generable and perishable.

[148] For things generated must be generated from something existent, and things which perish must perish into something existent, according to the postulates of the Dogmatists themselves. ¹¹ If, then, time perishes into the past, it perishes into a non-existent; and if it is generated out of the future, it is generated out of a non-existent; for neither of these is in existence. But it is absurd to say that anything is generated from a non-existent or perishes into the non-existent. Therefore time is not generable and perishable. But if it is neither ingenerable and imperishable nor generable and perishable, it does not exist at all.

[149] Further, since everything which becomes seems to become in time, time, if it becomes, becomes in time. Either, then, it becomes itself in itself or as one time in another. But if it becomes in itself, it will be at once both existent and non-existent. For since that within which a thing becomes must exist before the thing which becomes within it, the time which becomes in itself does not yet exist in so far as it becomes, but does already exist in so far as it becomes in itself. ¹² Consequently it does not become in itself.

[150] Nor yet in another. For if the present becomes in the future, the present will be future, and if in the past, it will be past. And the same may be said of all the other times; so that one time does not become in another. But if time neither becomes in itself nor as one time in another it is not generable. And it has been shown that it is not ingenerable either. Being, then, neither generable nor ingenerable, it is wholly non-existent; for each existing thing is bound to be either generable or ingenerable.