who will but obferve what paffes in his own mind, that there is a train of ideas, which conftantly fucceed one another in his understanding, as long as he is awake. Reflection on these appearances of feveral ideas, one after another, in our minds, is that which furnishes us with the idea of fucceffion; and the distance between any parts of that fucceffion, or between the appearance of any two ideas in our minds, is that we call duration: For whilst we are thinking, or whilft we receive fucceffively feveral ideas in our minds, we know that we do exist; and fo we call the existence, or the continuation of the existence of ourfelves, or any thing else commenfurate to the fucceffion of any ideas in our minds, the duration of ourfelves, or any fuch other thing co-existing with our thinking.

§ 4.

THAT we have our notion of fucceffion and duration from this original, viz. from reflection on the train of ideas which we find to appear one after another in our minds, feems plain to me, in that we have no perception of duration, but by confidering the train of ideas that take their turns in our understandings. When that fucceflion of ideas ceafes, our perception of duration ceafes with it; which every one clearly experiments in himself, whilft he fleeps foundly, whether an hour or a day, a month or a year; of which duration of things, whilft he fleeps or thinks not, he has no perception at all, but it is quite loft to him; and the moment wherein he leaves off to think, till the moment he begins to think again, seems to him to have no distance. And fo I doubt not, it would be to a waking man, if it were poffible for him to keep only one idea in his mind, without variation and the fucceffion of others; and we see, that one who fixes his thoughts very intently on one thing, fo as to take but little notice of the fucceffion of ideas that pafs in his mind, whilft he is taken up with that earnest contemplation, lets flip out of his account a good part of that duration, and thinks that time shorter than it is. But if fleep commonly unites the distant parts of duration, it is becaufe during that time we have

Book II. no fucceffion of ideas in our minds: For if a man during his fleep dreams, and variety of ideas make themfelves perceptible in his mind, one after another, he hath then, during fuch a dreaming, a fenfation of du ration, and of the length of it; by which it is to me very clear, that men derive their ideas of duration from their reflection on the train of the ideas they obferve to fucceed one another in their own underftandings; without which obfervation they can have no notion of duration, whatever may happen in the world.

$5. The Ideas of Duration applicable to things whilft

we fleep.

INDEED, a man having, from reflecting on the fucceffion and number of his own thoughts, got the notion or idea of duration, he can apply that notion to things which exist while he does not think; as he that has got the idea of extenfion from bodies by his fight or touch, can apply it to distances, where no body is feen or felt; and therefore, though a man has no perception of the length of duration which pafled whilft he flept or thought not, yet having obferved the revolution of days and nights, and found the length of their duration to be in appearance regular and conftant, he can, upon the fuppofition that that revolution has proceeded after the fame manner, whilst he was afleep or thought not, as it used to do at other times; he can, I fay, imagine and make allowance for the length of duration whilft he flept. But if Adam and Eve (when they were alone in the world), inftead of their ordinary night's fleep, had paffed the whole twenty-four hours in one continued fleep, the duration of that twenty-four hours had been irrecoverably loft to them, and been for ever left out of their account of time.

§ 6. The Idea of Succeffion not from Motion THUS, by reflecting on the appearing of various ideas one after another in our understandings, we get the notion of fucceffion, which if any one fhould think we did rather get from our obfervation of motion by our fenfes, he will perhaps be of my mind, when he confiders, that eyen motion produces in his mind an idea of fucceffion,.

no otherwife than as it produces there a continued train of diftinguishable ideas: For a man, looking upon a body really moving, perceives yet no motion at all, unlefs that motion produces a conftant train of fucceffive ideas; v. g. a man becalmed at fea, out of fight of land, in a fair day, may look on the fun, or fea, or fhip, a whole hour together, and perceive no motion at all in either; though it be certain, that two, and perhaps all of them, have moved during that time a great way; but as foon as he perceives either of them to have changed distance with fome other body, as foon as this motion produces any new idea in him, then he perceives that there has been motion. But wherever a man is, with all things at reft about him, without perceiving any motion at all; if during this hour of quiet he has been thinking, he will perceive the various ideas of his own thoughts in his own mind, appearing one after another, and thereby obferve and find fucceflion where he could obferve no motion.

§ 7.

AND this, I think, is the reafon, why motions very flow, though they are conftant, are not perceived by us; becaufe, in their remove from one fenfible part towards another, their change of distance is fo flow, that it caufes no new ideas in us, but a good while one after another; and so not causing a conftant train of new ideas to follow one another immediately in our minds, we have no perception of motion, which confifting in a conftant fucceffion, we cannot perceive that fucceffion without a conftant fucceffion of varying ideas arifing from it.

$ 8.

On the contrary, things that move so swift as not to affect the fenfes diftinctly with feveral diftinguishable diftances of their motion, and fo caufe not any train of ideas in the mind, are not alfo perceived to move; for any thing that moves round about in a circle, in lefs time than our ideas are wont to fucceed one another in our minds, is not perceived to move, but feems to be a per

fect entire circle of that matter or colour, and not a of a circle in motion.

part

§ 9. The Train of Ideas has a certain degree of Quick

nefs.

HENCE I leave it to others to judge, whether it be not probable that our ideas do, whilft we are awake, succeed one another in our minds at certain distances, not much unlike the images in the infide of a lanthorn, turned round by the heat of a candle. This appearance of theirs in train, though perhaps it may be fometimes fafter and fometimes flower, yet, I guess, varies not very much in a waking man. There feem to be certain bounds to the quickness and flowness of the fucceffion of those ideas one to another in our minds, beyond which they can neither delay nor haften.

§ 10.

THE reason I have for this odd conjecture, is from obferving, that in the impreffions made upon any of our fenfes, we can but to a certain degree perceive any fucceffion; which, if exceeding quick, the fenfe of fucceffion is loft, even in cafes where it is evident that there is a real fucceffion. Let a cannon bullet pafs through a room, and in its way take with it any limb, or fleshy parts of a man, it is as clear as any demonftration can be, that it must strike fucceffively the two fides of the room: It is also evident, that it must touch one part of the flesh first, and another after, and fo in fucceffion; and yet I believe nobody who ever felt the pain of fuch a shot, or heard the blow against the two diftant walls, could perceive any fucceffion, either in the pain or found of so swift a ftroke. Such a part of duration as this, wherein we perceive no fucceffion, is that which we may call an infant, and is that which takes up the time of only one idea in our minds, without the fucceffion of another, wherein therefore we perceive. no fucceffion at all.

THIS alfo happens, where the motion is so flow as not to fupply a conftant train of fresh ideas to the fenfes, as faft as the mind is capable of receiving new ones

into it; and fo other ideas of our own thoughts, having room to come into our minds, between those offered to our fenfes by the moving body, there the fenfe of motion is loft; and the body, though it really moves, yet not changing perceivable diftance with fome other bodies as fast as the ideas of our own minds do naturally follow one another in train, the thing feems to ftand ftill, as is evident in the hands of clocks and fhadows of fundials, and other conftant but flow motions; where, though, after certain intervals, we perceive by the change of distance that it hath moved, yet the motion itself we perceive not.

§ 12. This train the Measure of other Succeffions. So that to me it feems, that the conftant and regular fucceffion of ideas in a waking man, is, as it were, the meafure and ftandard of all other fucceffions, whereof if any one either exceeds the pace of our ideas, as where two founds or pains, &c. take up in their fucceffion the duration of but one idea, or elfe where any motion or fucceffion is fo flow as that it keeps not pace with the ideas in our minds, or the quicknefs in which they take their turns; as when any one or more ideas, in their ordinary course, come into our mind, between those which are offered to the fight by the different perceptible distances of a body in motion, or between founds or fmells following one another, there also the nfe of a conftant continued fucceffion is loft, and we perceive it not but with certain gaps of rest between.

13. The Mind cannot fix long on one invariable Idea. If it be fo that the ideas of our minds, whilft we have any there, do conftantly change and fhift in a continual fucceffion, it would be impoflible, may any one fay, for a man to think long of any one thing. By which, if it be meant that a man may have one felf-fame single idea a long time alone in his mind, without any variation at all, I think, in matter of fact, it is not pofJible; for which (not knowing how the ideas of our minds are framed, of what materials they are made, whence they have their light, and how they come to make their appearances) I can give no other reason