1. Duration is fleeting extension. There is another sort of distance, or length, the idea whereof we
get not from the permanent parts of space, but from the fleeting and perpetually perishing parts of
succession. This we call duration; the simple modes whereof are any different lengths of it whereof
we have distinct ideas, as hours, days, years, etc., time and eternity.
2. Its idea from reflection on the train of our ideas. The answer of a great man, to one who asked
what time was: Si non rogas intelligo, (which amounts to this; The more I set myself to think of it, the
less I understand it,) might perhaps persuade one that time, which reveals all other things, is itself
not to be discovered. Duration, time, and eternity, are, not without reason, thought to have
something very abstruse in their nature. But however remote these may seem from our
comprehension, yet if we trace them right to their originals, I doubt not but one of those sources of
all our knowledge, viz., sensation and reflection, will be able to furnish us with these ideas, as clear
and distinct as many others which are thought much less obscure; and we shall find that the idea of
eternity itself is derived from the same common original with the rest of our ideas.
3. Nature and origin of the idea of duration. To understand time and eternity aright, we ought with
attention to consider what idea it is we have of duration, and how we came by it. It is evident to any
one who will but observe what passes in his own mind, that there is a train of ideas which constantly
succeed one another in his understanding, as long as he is awake. Reflection on these
appearances of several ideas one after another in our minds, is that which furnishes us with the idea
of succession: and the distance between any parts of that succession, or between the appearance
of any two ideas in our minds, is that we call duration. For whilst we are thinking, or whilst we
receive successively several ideas in our minds, we know that we do exist; and so we call the
existence, or the continuation of the existence of ourselves, or anything else, commensurate to the
succession of any ideas in our minds, the duration of ourselves, or any such other thing co-existent
with our thinking.
4. Proof that its idea is got from reflection on the train of our ideas. That we have our notion of
succession and duration from this original, viz., from reflection on the train of ideas, which we find to
appear one after another in our own minds, seems plain to me, in that we have no perception of
duration but by considering the train of ideas that take their turns in our understandings. When that
succession of ideas ceases, our perception of duration ceases with it; which every one clearly
experiments in himself, whilst he sleeps soundly, whether an hour or a day, a month or a year; of
which duration of things, while he sleeps or thinks not, he has no perception at all, but it is quite lost
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 so I doubt not it would be to a waking man, if it were
possible for him to keep only one idea in his mind, without variation and the succession of others.
And we see, that one who fixes his thoughts very intently on one thing, so as to take but little notice
of the succession of ideas that pass in his mind, whilst he is taken up with that earnest
contemplation, lets slip out of his account a good part of that duration, and thinks that time shorter
than it is. But if sleep commonly unites the distant parts of duration, it is because during that time we
have no succession of ideas in our minds. For if a man, during his sleep, dreams, and variety of
ideas make themselves perceptible in his mind one after another, he hath then, during such
dreaming, a sense of duration, and of the length of it. By which it is to me very clear, that men derive
their ideas of duration from their reflections on the train of the ideas they observe to succeed one
another in their own understandings; without which observation they can have no notion of duration,
whatever may happen in the world.
5. The idea of duration applicable to things whilst we sleep. Indeed a man having, from reflecting on
the succession 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 extension from
bodies by his sight or touch, can apply it to distances, where no body is seen or felt. And therefore,
though a man has no perception of the length of duration which passed whilst he slept or thought
not; yet, having observed the revolution of days and nights, and found the length of their duration to
be in appearance regular and constant, he can, upon the supposition that that revolution has
proceeded after the same manner whilst he was asleep or thought not, as it used to do at other
times, he can, I say, imagine and make allowance for the length of duration whilst he slept. But if
Adam and Eve, (when they were alone in the world), instead of their ordinary night's sleep, had
passed the whole twenty-four hours in one continued sleep, the duration of that twenty-four hours
had been irrecoverably lost to them, and been for ever left out of their account of time.
6. The idea of succession not from motion. Thus by reflecting on the appearing of various ideas one
after another in our understandings, we get the notion of succession; which, if any one should think
we did rather get from our observation of motion by our senses, he will perhaps be of my mind when
he considers, that even motion produces in his mind an idea of succession no otherwise than as it
produces there a continued train of distinguishable ideas. For a man looking upon a body really
moving, perceives yet no motion at all unless that motion produces a constant train of successive
ideas: v.g. a man becalmed at sea, out of sight of land, in a fair day, may look on the sun, or sea, or
ship, 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 soon as he perceives either of
them to have changed distance with some other body, as soon 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
rest 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 observe and find succession where he could observe no motion.
7. Very slow motions unperceived. And this, I think, is the reason why motions very slow, though
they are constant, are not perceived by us; because in their remove from one sensible part towards
another, their change of distance is so slow, that it causes no new ideas in us, but a good while one
after another. And so not causing a constant train of new ideas to follow one another immediately in
our minds, we have no perception of motion; which consisting in a constant succession, we cannot
perceive that succession without a constant succession of varying ideas arising from it.
8. Very swift motions unperceived. On the contrary, things that move so swift as not to affect the
senses distinctly with several distinguishable distances of their motion, and so cause not any train of
ideas in the mind, are not also perceived. For anything that moves round about in a circle, in less
times than our ideas are wont to succeed one another in our minds, is not perceived to move; but
seems to be a perfect entire circle of that matter or colour, and not a part of a circle in motion.
9. The train of ideas has a certain degree of quickness. Hence I leave it to others to judge, whether
it be not probable that our ideas do, whilst we are awake, succeed one another in our minds at
certain distances; not much unlike the images in the inside of a lantern, turned round by the heat of
a candle. This appearance of theirs in train, though perhaps it may be sometimes faster and
sometimes slower, yet, I guess, varies not very much in a waking man: there seem to be certain
bounds to the quickness and slowness of the succession of those ideas one to another in our
minds, beyond which they can neither delay nor hasten.
10. Real succession in swift motions without sense of succession. The reason I have for this odd
conjecture is, from observing that, in the impressions made upon any of our senses, we can but to a
certain degree perceive any succession; which, if exceeding quick, the sense of succession is lost,
even in cases where it is evident that there is a real succession. Let a cannon-bullet pass through a
room, and in its way take with it any limb, or fleshy parts of a man, it is as clear as any
demonstration can be, that it must strike successively the two sides of the room: it is also evident
that it must touch one part of the flesh first, and another after, and so in succession: and yet, I
believe, nobody who ever felt the pain of such a shot, or heard the blow against the two distant
walls, could perceive any succession either in the pain or sound of so swift a stroke. Such a part of
duration as this, wherein we perceive no succession, is that which we call an instant, and is that
which takes up the time of only one idea in our minds, without the succession of another; wherein,
therefore, we perceive no succession at all.
11. In slow motions. This also happens where the motion is so slow as not to supply a constant train
of fresh ideas to the senses, as fast as the mind is capable of receiving new ones into it; and so
other ideas of our own thoughts, having room to come into our minds between those offered to our
senses by the moving body, there the sense of motion is lost; and the body, though it really moves,
yet, not changing perceivable distance with some other bodies as fast as the ideas of our own minds
do naturally follow one another in train, the thing seems to stand still; as is evident in the hands of
clocks, and shadows of sun-dials, and other constant but slow 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 successions. So that to me it seems, that the constant and
regular succession of ideas in a waking man, is, as it were, the measure and standard of all other
successions. Whereof, if any one either exceeds the pace of our ideas, as where two sounds or
pains, etc., take up in their succession the duration of but one idea; or else where any motion or
succession is so slow, as that it keeps not pace with the ideas in our minds, or the quickness 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 sight by the different perceptible distances of a body in
motion, or between sounds or smells following one another,--there also the sense of a constant
continued succession is lost, 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 so, that the ideas of our minds, whilst we
have any there, do constantly change and shift in a continual succession, it would be impossible,
may any one say, for a man to think long of any one thing. By which, if it be meant that a man may
have one self-same single idea a long time alone in his mind, without any variation at all, I think, in
matter of fact, it is not possible. 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 but experience: and I would have any one try, whether he
can keep one unvaried single idea in his mind, without any other, for any considerable time
together.
14. Proof. For trial, let him take any figure, any degree of light or whiteness, or what other he
pleases, and he will, I suppose, find it difficult to keep all other ideas out of his mind; but that some,
either of another kind, or various considerations of that idea, (each of which considerations is a new
idea), will constantly succeed one another in his thoughts, let him be as wary as he can.
15. The extent of our power over the succession of our ideas. All that is in a man's power in this
case, I think, is only to mind and observe what the ideas are that take their turns in his
understanding; or else to direct the sort, and call in such as he hath a desire or use of: but hinder
the constant succession of fresh ones, I think he cannot, though he may commonly choose whether
he will heedfully observe and consider them.
16. Ideas, however made, include no sense of motion. Whether these several ideas in a man's mind
be made by certain motions, I will not here dispute; but this I am sure, that they include no idea of
motion in their appearance; and if a man had not the idea of motion otherwise, I think he would have
none at all, which is enough to my present purpose; and sufficiently shows that the notice we take of
the ideas of our own minds, appearing there one after another, is that which gives us the idea of
succession and duration, without which we should have no such ideas at all. It is not then motion,
but the constant train of ideas in our minds whilst we are waking, that furnishes us with the idea of
duration; whereof motion no otherwise gives us any perception than as it causes in our minds a
constant succession of ideas, as I have before showed: and we have as clear an idea of succession
and duration, by the train of other ideas succeeding one another in our minds, without the idea of
any motion, as by the train of ideas caused by the uninterrupted sensible change of distance
between two bodies, which we have from motion; and therefore we should as well have the idea of
duration were there no sense of motion at all.
17. Time is duration set out by measures. Having thus got the idea of duration, the next thing natural
for the mind to do, is to get some measure of this common duration, whereby it might judge of its
different lengths, and consider the distinct order wherein several things exist; without which a great
part of our knowledge would be confused, and a great part of history be rendered very useless. This
consideration of duration, as set out by certain periods, and marked by certain measures or epochs,
is that, I think, which most properly we call time.
18. A good measure of time must divide its whole duration into equal periods. In the measuring of
extension, there is nothing more required but the application of the standard or measure we make
use of to the thing of whose extension we would be informed. But in the measuring of duration this
cannot be done, because no two different parts of succession can be put together to measure one
another. And nothing being a measure of duration but duration, as nothing is of extension but
extension, we cannot keep by us any standing, unvarying measure of duration, which consists in a
constant fleeting succession, as we can of certain lengths of extension, as inches, feet, yards, etc.,
marked out in permanent parcels of matter. Nothing then could serve well for a convenient measure
of time, but what has divided the whole length of its duration into apparently equal portions, by
constantly repeated periods. What portions of duration are not distinguished, or considered as
distinguished and measured, by such periods, come not so properly under the notion of time; as
appears by such phrases as these, viz., "Before all time," and "When time shall be no more."
19. The revolutions of the sun and moon, the properest measures of time for mankind. The diurnal
and annual revolutions of the sun, as having been, from the beginning of nature, constant, regular,
and universally observable by all mankind, and supposed equal to one another, have been with
reason made use of for the measure of duration. But the distinction of days and years having
depended on the motion of the sun, it has brought this mistake with it, that it has been thought that
motion and duration were the measure one of another. For men, in the measuring of the length of
time, having been accustomed to the ideas of minutes, hours, days, months, years, etc., which they
found themselves upon any mention of time or duration presently to think on, al which portions of
time were measured out by the motion of those heavenly bodies, they were apt to confound time
and motion; or at least to think that they had a necessary connexion one with another. Whereas any
constant periodical appearance, or alteration of ideas, in seemingly equidistant spaces of duration, if
constant and universally observable, would have as well distinguished the intervals of time, as those
that have been made use of. For, supposing the sun, which some have taken to be a fire, had been
lighted up at the same distance of time that it now every day comes about to the same meridian,
and then gone out again about twelve hours after, and that in the space of an annual revolution it
had sensibly increased in brightness and heat, and so decreased again,--would not such regular
appearances serve to measure out the distances of duration to all that could observe it, as well
without as with motion? For if the appearances were constant, universally observable, in equidistant
periods, they would serve mankind for measure of time as well were the motion away.
20. But not by their motion, but periodical appearances. For the freezing of water, or the blowing of a
plant, returning at equidistant periods in all parts of the earth, would as well serve men to reckon
their years by as the motions of the sun: and in effect we see, that some people in America counted
their years by the coming of certain birds amongst them at their certain seasons, and leaving them
at others. For a fit of an ague; the sense of hunger or thirst; a smell or a taste; or any other idea
returning constantly at equidistant periods, and making itself universally be taken notice of, would
not fail to measure out the course of succession, and distinguish the distances of time. Thus we see
that men born blind count time well enough by years, whose revolutions yet they cannot distinguish
by motions that they perceive not. And I ask whether a blind man, who distinguished his years either
by the heat of summer, or cold of winter; by the smell of any flower of the spring, or taste of any fruit
of the autumn, would not have a better measure of time than the Romans had before the
reformation of their calendar by Julius Caesar, or many other people whose years, notwithstanding
the motion of the sun, which they pretended to make use of, are very irregular? And it adds no small
difficulty to chronology, that the exact lengths of the years that several nations counted by, are hard
to be known, they differing very much one from another, and I think I may say all of them from the
precise motion of the sun. And if the sun moved from the creation to the flood constantly in the
equator, and so equally dispersed its light and heat to all the habitable parts of the earth, in days all
of the same length, without its annual variations to the tropics, as a late ingenious author supposes,
I do not think it very easy to imagine, that (notwithstanding the motion of the sun) men should in the
antediluvian world, from the beginning, count by years, or measure their time by periods that had no
sensible marks very obvious to distinguish them by.
21. No two parts of duration can be certainly known to be equal. But perhaps it will be said,--without
a regular motion, such as of the sun, or some other, how could it ever be known that such periods
were equal? To which I answer,--the equality of any other returning appearances might be known by
the same way that that of days was known, or presumed to be so at first; which was only by judging
of them by the train of ideas which had passed in men's minds in the intervals; by which train of
ideas discovering inequality in the natural days, but none in the artificial days, the artificial days, or
nuchtheerha, were guessed to be equal, which was sufficient to make them serve for a measure;
though exacter search has since discovered inequality in the diurnal revolutions of the sun, and we
know not whether the annual also be not unequal. These yet, by their presumed and apparent
equality, serve as well to reckon time by (though not to measure the parts of duration exactly) as if
they could be proved to be exactly equal. We must, therefore, carefully distinguish betwixt duration
itself, and the measures we make use of to judge of its length. Duration, in itself, is to be considered
as going on in one constant, equal, uniform course: but none of the measures of it which we make
use of can be known to do so, nor can we be assured that their assigned parts or periods are equal
in duration one to another; for two successive lengths of duration, however measured, can never be
demonstrated to be equal. The motion of the sun, which the world used so long and so confidently
for an exact measure of duration, has, as I said, been found in its several parts unequal. And though
men have, of late, made use of a pendulum, as a more steady and regular motion than that of the
sun, or, (to speak more truly), of the earth;--yet if any one should be asked how he certainly knows
that the two successive swings of a pendulum are equal, it would be very hard to satisfy him that
they are infallibly so; since we cannot be sure that the cause of that motion, which is unknown to us,
shall always operate equally; and we are sure that the medium in which the pendulum moves is not
constantly the same: either of which varying, may alter the equality of such periods, and thereby
destroy the certainty and exactness of the measure by motion, as well as any other periods of other
appearances; the notion of duration still remaining clear, though our measures of it cannot (any of
them) be demonstrated to be exact. Since then no two portions of succession can be brought
together, it is impossible ever certainly to know their equality. All that we can do for a measure of
time is, to take such as have continual successive appearances at seemingly equidistant periods; of
which seeming equality we have no other measure, but such as the train of our own ideas have
lodged in our memories, with the concurrence of other probable reasons, to persuade us of their
equality.
22. Time not the measure of motion. One thing seems strange to me,--that whilst all men manifestly
measured time by the motion of the great and visible bodies of the world, time yet should be defined
to be the "measure of motion": whereas it is obvious to every one who reflects ever so little on it, that
to measure motion, space is as necessary to be considered as time; and those who look a little
farther will find also the bulk of the thing moved necessary to be taken into the computation, by any
one who will estimate or measure motion so as to judge right of it. Nor indeed does motion any
otherwise conduce to the measuring of duration, than as it constantly brings about the return of
certain sensible ideas, in seeming equidistant periods. For if the motion of the sun were as unequal
as of a ship driven by unsteady winds, sometimes very slow, and at others irregularly very swift; or
if, being constantly equally swift, it yet was not circular, and produced not the same appearances,--it
would not at all help us to measure time, any more than the seeming unequal motion of a comet
does.
23. Minutes, hours, days, and years not necessary measures of duration. Minutes, hours, days, and
years are, then, no more necessary to time or duration, than inches, feet, yards, and miles, marked
out in any matter, are to extension. For, though we in this part of the universe, by the constant use of
them, as of periods set out by the revolutions of the sun, or as known parts of such periods, have
fixed the ideas of such lengths of duration in our minds, which we apply to all parts of time whose
lengths we would consider; yet there may be other parts of the universe, where they no more use
there measures of ours, than in Japan they do our inches, feet, or miles; but yet something
analogous to them there must be. For without some regular periodical returns, we could not
measure ourselves, or signify to others, the length of any duration; though at the same time the
world were as full of motion as it is now, but no part of it disposed into regular and apparently
equidistant revolutions. But the different measures that may be made use of for the account of time,
do not at all alter the notion of duration, which is the thing to be measured; no more than the
different standards of a foot and a cubit alter the notion of extension to those who make use of those
different measures.
24. Our measure of time applicable to duration before time. The mind having once got such a
measure of time as the annual revolution of the sun, can apply that measure to duration wherein
that measure itself did not exist, and with which, in the reality of its being, it had nothing to do. For
should one say, that Abraham was born in the two thousand seven hundred and twelfth year of the