An Essay Concerning Humane Understanding Vol I Chapter XIV. - Idea of Duration and its Simple Modes
by John Locke
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, &c., 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 the 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, &c., 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, &c., 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, &c., which they found themselves upon any mention of
time or duration presently to think on, all 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 mark 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 nuchthaemera, 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 are, then, no more Minutes, Hours,
Days, and Years not necessary Measures of Duration. 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 these 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 Julian period, it is
altogether as intelligible as reckoning from the beginning of the world,
though there were so far back no motion of the sun, nor any motion at
all. For, though the Julian period be supposed to begin several hundred
years before there were really either days, nights, or years, marked
out by any revolutions of the sun,--yet we reckon as right, and thereby
measure durations as well, as if really at that time the sun had
existed, and kept the same ordinary motion it doth now. The idea
of duration equal to an annual revolution of the sun, is as easily
APPLICABLE in our thoughts to duration, where no sun or motion was, as
the idea of a foot or yard, taken from bodies here, can be applied in
our thoughts to duration, where no sun or motion was, as the idea of a
foot or yard, taken from bodies here, can be applied in our thoughts to
distances beyond the confines of the world, where are no bodies at all.
25. As we can measure space in our thoughts where there is no body.
For supposing it were 5639 miles, or millions of miles, from this place
to the remotest body of the universe, (for, being finite, it must be at
a certain distance,) as we suppose it to be 5639 years from this time to
the first existence of any body in the beginning of the world;--we can,
in our thoughts, apply this measure of a year to duration before the
creation, or beyond the duration of bodies or motion, as we can this
measure of a mile to space beyond the utmost bodies; and by the one
measure duration, where there was no motion, as well as by the other
measure space in our thoughts, where there is no body.
26. The assumption that the world is neither boundless nor eternal.
If it be objected to me here, that, in this way of explaining of time,
I have begged what I should not, viz. that the world is neither eternal
nor infinite; I answer, That to my present purpose it is not needful, in
this place, to make use of arguments to evince the world to be finite
both in duration and extension. But it being at least as conceivable as
the contrary, I have certainly the liberty to suppose it, as well as any
one hath to suppose the contrary; and I doubt not, but that every one
that will go about it, may easily conceive in his mind the beginning of
motion, though not of all duration, and so may come to a step and non
ultra in his consideration of motion. So also, in his thoughts, he may
set limits to body, and the extension belonging to it; but not to space,
where no body is, the utmost bounds of space and duration being beyond
the reach of thought, as well as the utmost bounds of number are beyond
the largest comprehension of the mind; and all for the same reason, as
we shall see in another place.
27. Eternity.
By the same means, therefore, and from the same original that we come to
have the idea of time, we have also that idea which we call Eternity;
viz. having got the idea of succession and duration, by reflecting
on the train of our own ideas, caused in us either by the natural
appearances of those ideas coming constantly of themselves into our
waking thoughts, or else caused by external objects successively
affecting our senses; and having from the revolutions of the sun got the
ideas of certain lengths of duration,--we can in our thoughts add such
lengths of duration to one another, as often as we please, and apply
them, so added, to durations past or to come. And this we can continue
to do on, without bounds or limits, and proceed in infinitum, and apply
thus the length of the annual motion of the sun to duration, supposed
before the sun's or any other motion had its being, which is no more
difficult or absurd, than to apply the notion I have of the moving of a
shadow one hour to-day upon the sun-dial to the duration of something
last night, v. g. the burning of a candle, which is now absolutely
separate from all actual motion; and it is as impossible for the
duration of that flame for an hour last night to co-exist with any
motion that now is, or for ever shall be, as for any part of duration,
that was before the beginning of the world, to co exist with the motion
of the sun now. But yet this hinders not but that, having the IDEA of
the length of the motion of the shadow on a dial between the marks of
two hours, I can as distinctly measure in my thoughts the duration of
that candle-light last night, as I can the duration of anything that
does now exist: and it is no more than to think, that, had the sun shone
then on the dial, and moved after the same rate it doth now, the shadow
on the dial would have passed from one hour-line to another whilst that
flame of the candle lasted.
28. Our measures of Duration dependent on our ideas.
The notion of an hour, day, or year, being only the idea I have of the
length of certain periodical regular motions, neither of which motions
do ever all at once exist, but only in the ideas I have of them in my
memory derived from my senses or reflection; I can with the same ease,
and for the same reason, apply it in my thoughts to duration antecedent
to all manner of motion, as well as to anything that is but a minute or
a day antecedent to the motion that at this very moment the sun is in.
All things past are equally and perfectly at rest; and to this way
of consideration of them are all one, whether they were before the
beginning of the world, or but yesterday: the measuring of any duration
by some motion depending not at all on the REAL co-existence of that
thing to that motion, or any other periods of revolution, but the having
a clear IDEA of the length of some periodical known motion, or other
interval of duration, in my mind, and applying that to the duration of
the thing I would measure.
29. The Duration of anything need not be co-existent with the motion we
measure it by.
Hence we see that some men imagine the duration of of the world, from
its first existence to this present year 1689, to have been 5639 years,
or equal to 5639 annual revolutions of the sun, and others a great deal
more; as the Egyptians of old, who in the time of Alexander counted
23,000 years from the reign of the sun; and the Chinese now, who account
the world 3,269,000 years old, or more; which longer duration of the
world, according to their computation, though I should not believe to be
true, yet I can equally imagine it with them, and as truly understand,
and say one is longer than the other, as I understand, that Methusalem's
life was longer than Enoch's. And if the common reckoning of 5639 should
be true, (as it may be as well as any other assigned,) it hinders not at
all my imagining what others mean, when they make the world one thousand
years older, since every one may with the same facility imagine (I do
not say believe) the world to be 50,000 years old, as 5639; and may as
well conceive the duration of 50,000 years as 5639. Whereby it appears
that, to the measuring the duration of anything by time, it is not
requisite that that thing should be co-existent to the motion we measure
by, or any other periodical revolution; but it suffices to this
purpose, that we have the idea of the length of ANY regular periodical
appearances, which we can in our minds apply to duration, with which the
motion or appearance never co-existed.
30. Infinity in Duration.
For, as in the history of the creation delivered by Moses, I can imagine
that light existed three days before the sun was, or had any motion,
barely by thinking that the duration of light before the sun was created
was so long as (IF the sun had moved then as it doth now) would have
been equal to three of his diurnal revolutions; so by the same way I can
have an idea of the chaos, or angels, being created before there was
either light or any continued motion, a minute, an hour, a day, a year,
or one thousand years. For, if I can but consider duration equal to one
minute, before either the being or motion of any body, I can add one
minute more till I come to sixty; and by the same way of adding minutes,
hours, or years (i.e. such or such parts of the sun's revolutions, or
any other period whereof I have the idea) proceed IN INFINITUM, and
suppose a duration exceeding as many such periods as I can reckon, let
me add whilst I will, which I think is the notion we have of eternity;
of whose infinity we have no other notion than we have of the infinity
of number, to which we can add for ever without end.
31. Origin of our Ideas of Duration, and of the measures of it.
And thus I think it is plain, that from those two fountains of all
knowledge before mentioned, viz. reflection and sensation, we got the
ideas of duration, and the measures of it.
For, First, by observing what passes in our minds, how our ideas there
in train constantly some vanish and others begin to appear, we come by
the idea of SUCCESSION. Secondly, by observing a distance in the parts
of this succession, we get the idea of DURATION.
Thirdly, by sensation observing certain appearances, at certain regular
and seeming equidistant periods, we get the ideas of certain LENGTHS or
MEASURES OF DURATION, as minutes, hours, days, years, &c.
Fourthly, by being able to repeat those measures of time, or ideas of
stated length of duration, in our minds, as often as we will, we can
come to imagine DURATION,--WHERE NOTHING DOES REALLY ENDURE OR EXIST;
and thus we imagine to-morrow, next year, or seven years hence.
Fifthly, by being able to repeat ideas of any length of time, as of a
minute, a year, or an age, as often as we will in our own thoughts,
and adding them one to another, without ever coming to the end of such
addition, any nearer than we can to the end of number, to which we can
always add; we come by the idea of ETERNITY, as the future eternal
duration of our souls, as well as the eternity of that infinite Being
which must necessarily have always existed.
Sixthly, by considering any part of infinite duration, as set out
by periodical measures, we come by the idea of what we call TIME in
general.