Duration and Its Simple Forms

1. Duration is fleeting Extension.

1. Duration is extension that passes away.

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.

There is another kind of distance, or length. Our idea of this length comes not from the lasting parts of space, but from successive moments that constantly pass away. We call this length DURATION. Its simple forms are the different lengths of duration that we have distinct ideas of. Examples include HOURS, DAYS, YEARS, and so on, TIME and ETERNITY.

2. Its Idea from Reflection on the Train of our Ideas.

2. The Idea of It Comes from Reflecting on the Sequence 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.

A great man, when asked what time was, answered: Si non rogas intelligo. (This amounts to saying: The more I try to think about time, the less I understand it.) His answer might perhaps persuade us that time, which reveals all other things, cannot itself be understood. Duration, time, and eternity are thought, with good reason, to have something deeply obscure in their nature. But however far beyond our understanding these ideas may seem, I have no doubt we can trace their origins. If we trace them correctly, either sensation or reflection, the two sources of all our knowledge, will provide these ideas. The ideas will be as clear and distinct as many others thought to be much less obscure. And we will find that even the idea of eternity comes from the same common source as our other ideas.

3. Nature and origin of the idea of Duration.

3. The 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.

To understand TIME and ETERNITY correctly, we must carefully consider our idea of DURATION and how we acquired it. Anyone who observes what happens in their own mind can plainly see a continuous sequence of ideas. These ideas follow one another in the mind as long as we are awake. Reflecting on how different ideas appear one after another gives us the idea of SUCCESSION. We call the distance between any parts of this succession DURATION. This includes the distance between the appearances of any two ideas in our minds. For while we are thinking, or receiving different ideas one after another, we know that we exist. So we measure our existence, or its continuation, against the succession of ideas in our minds. We call the existence measured in this way our duration. The same applies to anything else that exists while we are thinking. We call its existence, or its continued existence, measured against that succession of ideas, its duration.

4. Proof that its idea is got from reflection on the train of our ideas.

4. Proof that our idea of it comes from reflecting on the sequence 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.

It seems clear to me that our ideas of succession and duration come from reflecting on our sequence of thoughts. We notice ideas appearing one after another in our minds. We perceive duration only by considering this sequence of ideas. When the sequence stops, our perception of duration stops too. Everyone clearly experiences this during sound sleep, whether sleeping for an hour, a day, a month, or a year. While someone sleeps or does not think, he has no perception at all of how long things last. That time is entirely lost to him. No interval seems to separate the moment he stops thinking from the moment he begins thinking again. I have no doubt the same would happen to someone awake, if he could hold ONLY ONE idea in mind. That idea would have to remain unchanged, with no other ideas following it. We also see what happens when someone concentrates so intensely on one thing that he barely notices his changing ideas. He leaves much of that duration out of his reckoning and thinks the time shorter than it is. But if sleep commonly makes widely separated moments seem to touch, this is because no ideas follow one another during sleep. For if someone dreams, and various ideas become perceptible in his mind one after another, he then perceives duration. During that dream, he also has a sense of how long the duration is. This makes it very clear to me that people derive their ideas of duration from reflecting on their own ideas. They observe those ideas following one another in their minds. Without that 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.

5. The idea of duration applies to things while 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.

Indeed, a person gains the idea of duration by reflecting on the sequence and number of his own thoughts. He can then apply that idea to things that exist while he is not thinking. Similarly, someone gains the idea of extension in space by seeing or touching bodies. He can then apply that idea to distances where he neither sees nor feels any body. So, although a person does not perceive how much time passes while he sleeps or does not think, he can estimate it. He has observed the cycle of days and nights and found that their duration appears regular and constant. He can suppose that this cycle continued as usual while he slept or did not think. On that assumption, he can, I say, imagine how much time passed while he slept and include it in his reckoning. But suppose Adam and Eve had slept continuously for twenty-four hours instead of their usual night's sleep. This would have been when they were alone in the world. Those twenty-four hours would have been irretrievably lost to them and forever left out of their reckoning of time.

6. The Idea of Succession not from Motion.

6. The idea of succession does not come 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.

By reflecting on how different ideas appear in our minds one after another, we get the notion of succession. Some may think we get this notion instead by observing motion through our senses. But perhaps they will agree with me when they consider how motion gives us an idea of succession. Motion does so only by producing a continuous series of distinct ideas in the mind. For someone watching a body actually move perceives no motion unless that movement produces a continuous series of successive ideas. For example, imagine a man on a ship with no wind at sea, out of sight of land, on a clear day. He may watch the sun, the sea, or the ship for a whole hour without perceiving motion in any of them. Yet certainly two, and perhaps all three, have moved a great distance during that time. But as soon as he notices that any of them has changed its distance from another body, he perceives movement. He perceives that movement as soon as it produces a new idea in his mind. But wherever a man is, everything around him may be at rest, and he may perceive no motion at all. If he has been thinking during this quiet hour, he will notice different ideas appearing in his mind, one after another. In this way, he will observe and discover succession where he could observe no motion.

7. Very slow motions unperceived.

7. Very slow movements go unnoticed.

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.

And this, I think, is why we do not perceive very slow movements, even though they are constant. As something moves from one perceptible position toward another, its distance changes so slowly that new ideas arise only at long intervals. So these movements do not produce a steady stream of new ideas following immediately after one another in our minds. As a result, we do not perceive motion. Motion consists of continuous change. We cannot perceive that change without a continuous series of changing ideas arising from the motion.

8. Very swift motions unperceived.

8. Very fast movements go unnoticed.

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.

On the contrary, we do not perceive things moving too fast for our senses to distinguish their successive positions. Such movements therefore produce no sequence of ideas in the mind. For example, an object may complete a circle faster than one idea usually follows another in our minds. In that case, we do not perceive the object as moving. Instead, we see a complete circle of material or colour, not part of a circle in motion.

9. The Train of Ideas has a certain Degree of Quickness.

9. Ideas follow one another at a certain speed.

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.

So I leave others to judge whether the following seems probable. While we are awake, our ideas follow one another in our minds at certain intervals. They are rather like images inside a lantern that turns with the heat of a candle. Although this sequence of ideas may sometimes move faster or slower, I suspect its pace varies little while we are awake. There seem to be limits to how quickly or slowly ideas can follow one another in our minds. Beyond these limits, the ideas can neither slow down nor speed up.

10. Real succession in swift motions without sense of succession.

10. Rapid movements happen in sequence, even when we do not perceive the sequence.

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.

My reason for this odd guess comes from observing how our senses register events happening one after another. We can perceive this sequence only up to a certain speed. If events happen too quickly, we lose the sense of sequence, even when the events clearly happen one after another. Suppose a cannonball passes through a room, taking someone's limb or part of their flesh with it. It is as certain as anything proved by demonstration that the ball must strike the room's two walls in succession. It is also clear that the ball must touch one part of the flesh first, then another, in succession. Yet I believe no one who felt the pain or heard the blows against the two distant walls could distinguish a sequence. Neither the pain nor the sound of such a swift strike would reveal one. A stretch of time in which we perceive no sequence is what we call an INSTANT. An instant lasts only as long as a single idea occupies our minds, without another idea following it. During that time, therefore, we perceive no sequence at all.

11. In slow motions.

11. In slow movements.

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.

This also happens when motion is too slow to provide the senses with a constant stream of fresh ideas. The ideas arrive more slowly than the mind can receive new ones. So ideas from our own thoughts have time to enter between those the moving body supplies to our senses. When this happens, we lose the sense of motion. Although the body really moves, its distance from other bodies does not change noticeably fast enough. The change is slower than the natural flow of ideas in our minds, so the body seems to stand still. We see this with clock hands, shadows on sundials, and other steady but slow movements. After certain intervals, we can tell from the change in distance that the body has moved. Yet we do not perceive the motion itself.

12. This Train, the Measure of other Successions.

12. This sequence measures other sequences.

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.

So it seems to me that ideas follow one another steadily and regularly in a person who is awake. This succession of IDEAS is, as it were, the measure and standard of all other successions. Some successions may move faster than our ideas. For example, two sounds or pains, and so on, may follow one another within the time of a single idea. Or a movement or succession may be too slow to keep pace with the ideas passing through our minds. For example, one or more ideas may enter our minds in their ordinary course between successive perceptions of movement. These perceptions come from seeing a moving body at different, visibly distinguishable positions. Ideas may likewise enter our minds between successive sounds or smells. In these cases too, we lose the sense of a steady, continuous succession. Instead, we perceive the succession with gaps of rest between its parts.

13. The Mind cannot fix long on one invariable Idea.

13. The mind cannot focus for long on a single, unchanging 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.

Suppose the ideas in our minds constantly change, following one another whenever any ideas are present. Someone may say that, if so, a person could not think about any one thing for long. Perhaps this means keeping exactly the same single idea alone in the mind, without any change, for a long time. If so, I think this is not actually possible. I can offer no reason for this beyond experience. I do not know how our ideas are formed or what materials they are made of. Nor do I know where their light comes from or how they come to appear. So I invite anyone to try keeping one unchanged idea in mind, without any others, for any considerable time.

14. Proof.

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.

As a test, let him choose any shape, any degree of light or whiteness, or anything else he pleases. I suppose he will find keeping all other ideas out of his mind difficult. But some ideas will constantly follow one another in his thoughts, however careful he is. These may be ideas of another kind or different ways of considering the idea he chose. Each way of considering that idea is itself a new idea.

15. The extent of our power over the succession of our ideas.

15. How much control we have over the sequence 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.

In this case, I think all a person can do is notice and observe the ideas passing through his mind. Or he can guide the kinds of ideas that arise, calling up those he wants or needs. But I think he cannot stop the constant flow of new ideas. Still, he can usually choose whether to pay close attention to those ideas and consider them.

16. Ideas, however made, include no sense of motion.

16. Ideas, however they are formed, contain 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.

I will not discuss here whether certain motions produce these various ideas in a person’s mind. But I am sure that these ideas, as they appear, contain no idea of motion. If a person had not gained the idea of motion elsewhere, I think they would have no such idea. That is enough for my present purpose. It sufficiently shows how we gain our ideas of succession and duration. We gain them by noticing the ideas appearing one after another in our own minds. Without noticing this sequence, we would have no ideas of succession or duration at all. So it is not MOTION that gives us the idea of duration. Rather, it is the constant flow of IDEAS in our minds while we are awake. As I showed earlier, motion gives us a perception of duration only by causing a constant succession of ideas. Other ideas following one another in our minds give us just as clear an idea of succession and duration. They do so even without any idea of motion. Our understanding is just as clear as when ideas arise from a continuous, perceptible change in distance between two bodies. Motion gives us that changing distance. So we would have the idea of duration just as well if we had no sense of motion at all.

17. Time is Duration set out by Measures.

17. Time is duration divided into measured units.

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.

Once the mind has gained the idea of duration, its next natural step is to find a measure of duration. Such a measure would let the mind judge different lengths of duration and understand the order in which things exist. Without such a measure, much of our knowledge would be confused, and much of history would become very unhelpful. Duration considered in terms of fixed periods and marked by specific measures or reference points is, I think, what we most properly call TIME.

18. A good Measure of Time must divide its whole Duration into equal Periods.

18. A good measure of time must divide the entire 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.’

To measure spatial extent, we need only apply our chosen standard or measure to the thing we want to measure. But we cannot measure duration in the same way. No two different parts of a succession can be brought together to measure one another. Only duration can measure duration, just as only spatial extent can measure spatial extent. So we cannot keep a fixed, unchanging measure of duration, because duration consists of a constantly passing succession. But we can keep fixed lengths, such as inches, feet, and yards, marked out in lasting pieces of matter. So only something with constantly repeated cycles could serve as a convenient measure of time. These cycles must divide the whole of its duration into apparently equal portions. Portions of duration not distinguished by such cycles, or not regarded as distinguished and measured by them, are less properly called time. We can see this in phrases such as ‘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.

19. The cycles of the Sun and Moon are the most suitable measures of time for humanity.

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.

The sun’s daily and yearly cycles have reasonably been used to measure duration. Since nature began, these cycles have been constant, regular, and observable by all humanity. Each daily cycle has been assumed equal to every other daily cycle, and each yearly cycle to every other yearly cycle. But distinguishing days and years by the sun’s motion has led to a mistake. People have come to think that motion and duration measure each other. When measuring time, people have grown used to thinking in minutes, hours, days, months, years, and so on. Whenever time or duration is mentioned, these units immediately come to mind. All these portions of time have been measured by the motion of heavenly bodies. So people have tended to confuse time with motion, or at least to think the two are necessarily connected. Yet any regularly recurring appearance or change in ideas could distinguish intervals of time just as well. Such events would need to be constant, observable by everyone, and separated by apparently equal intervals of duration. Suppose the sun, which some have considered a fire, lit up at regular intervals. Suppose those intervals matched the time the sun now takes to return each day to the same meridian. Then suppose the sun went out again about twelve hours later. Over the course of a year, suppose its brightness and heat noticeably increased and then decreased again. Wouldn’t these regular appearances measure intervals of duration for everyone able to observe them, just as well without motion as with it? If these appearances were constant, observable by everyone, and equally spaced, they would measure time just as well without motion.

20. But not by their Motion, but periodical Appearances.

20. But not by their movement, but by their regular appearances.

For the freezing of water, or the blooming 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.

Suppose water froze or a plant bloomed at equal intervals in all parts of the earth. These events would serve people just as well for counting years as the sun’s movements. In fact, some people in America counted their years by the arrival and departure of certain birds at regular seasons. A bout of fever, hunger or thirst, a smell or taste, or any other idea could serve the same purpose. Such experiences would only need to return regularly at equal intervals and attract everyone’s notice. They would then reliably measure the passage of time and distinguish one interval from another. Thus, people born blind can count time well enough in years. Yet they cannot distinguish the yearly cycles by movements they cannot perceive. Suppose a blind man distinguished years by summer’s heat or winter’s cold. Or suppose he used the smell of a spring flower or the taste of an autumn fruit. Would he not measure time better than the Romans did before Julius Caesar reformed their calendar? Would he not also measure it better than many other peoples whose years are very irregular? Those peoples claim to use the sun’s movements, yet their years remain irregular. The difficulty of finding the exact lengths of different nations’ years also makes chronology considerably harder. Those years differ greatly from one another and, I think I may say, all differ from the sun’s precise cycle. A recent, ingenious author offers a further possibility. Suppose the sun moved constantly along the equator from the creation to the flood. Suppose its light and heat therefore spread equally over all habitable parts of the earth. All days would have been equally long, without the sun’s annual shifts toward the tropics. Under those conditions, I find it hard to imagine people before the flood counting years from the beginning. Despite the sun’s movement, how would they have measured time by periods with no readily apparent sign to distinguish them?

21. No two Parts of Duration can be certainly known to be equal.

21. No two periods of time can be known with certainty to be equal in length.

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.

But perhaps someone will ask how we could ever know that such periods were equal without a regular motion. Such a motion might be the sun’s, or some other motion. I answer that we could judge the equality of other recurring events just as we first judged days equal. At first, people knew, or assumed, that days were equal only by considering the sequence of ideas between them. This sequence revealed differences in the length of daylight, but none in the full cycles of day and night. So people guessed that these full days, or nuchthaemera, were equal. That was enough to make them useful as a measure. Yet more precise investigation has since revealed inequalities in the sun’s daily revolutions. And we do not know whether its yearly revolutions are also unequal. Still, these revolutions seem equal and are assumed to be equal. They therefore serve to reckon time as well as if we could prove them exactly equal. They do not, however, measure portions of duration exactly. We must therefore carefully distinguish duration itself from the measures we use to judge its length. Duration itself must be considered as proceeding in one constant, even, uniform course. But none of our measures of duration can be KNOWN to do the same. Nor can we be certain that their specified parts or periods are equal in duration. For no two successive lengths of duration, however measured, can ever be proved equal. The world long relied confidently on the sun’s motion as an exact measure of duration. Yet, as I have said, different parts of that motion have been found unequal. More recently, people have used a pendulum because its motion is steadier and more regular than the sun’s. More accurately, the comparison is with the earth’s motion. Yet suppose someone were asked how he knows for certain that two successive swings of a pendulum are equal. It would be very hard to convince him that the swings are unfailingly equal. We do not know the cause of that motion, so we cannot be sure that the cause always acts equally. And we are certain that the medium through which the pendulum moves does not always remain the same. A change in either could make the periods unequal. Such changes could undermine the certainty and precision of measurement by motion, just as with other recurring events. Our idea of duration nevertheless remains clear, though none of our measures of duration can be proved exact. Since no two successive portions of duration can be brought together, we can never know for certain that they are equal. All we can do to measure time is choose events that recur continually at seemingly equal intervals. Our only measure of this apparent equality is the sequence of our own ideas preserved in memory. Other PROBABLE reasons join with this measure to persuade us that the intervals are equal.

22. Time not the Measure of Motion

22. Time Is 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.

One thing seems strange to me. All people clearly measure time by the motion of the great, visible bodies in the world. Yet time is defined as the ‘measure of motion’. But anyone who thinks about the matter even briefly can see that measuring motion requires considering space as well as time. Those who look a little further will also see that the size of the moving body must enter the calculation. Anyone who wants to assess or measure motion accurately must consider this size. Motion helps us measure duration only by repeatedly producing certain sensory impressions at apparently equal intervals. Suppose the sun moved as unevenly as a ship driven by shifting winds. Sometimes the sun would move very slowly, and at other times irregularly and very quickly. Or suppose the sun always moved at the same speed, but not in a circle, without producing the same appearances. In either case, the sun's motion would no more help us measure time than a comet's apparently uneven motion 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.

23. Minutes, hours, days, and years are not necessary measures of duration. These units are no more necessary to time or duration than inches, feet, yards, and miles marked on physical objects are to extension, or spatial size. In our part of the universe, constant use has fixed these lengths of duration in our minds. We use them as periods marked by the sun’s revolutions, or as known parts of those periods. We apply these units to all stretches of time whose length we want to consider. Yet there may be other parts of the universe where our measures are no more used than our inches, feet, or miles are in Japan. But something comparable to our measures must exist there. Without some regular, recurring events, we could neither measure a duration ourselves nor communicate its length to others. This would remain true even if the world were as full of motion as it is now. Without movements recurring at regular and apparently equal intervals, we could not measure duration. But using different measures to keep track of time does not change the idea of duration, the thing being measured. Different standards, such as a foot and a cubit, likewise do not change their users’ idea of extension.

24. Our Measure of Time applicable to Duration before Time.

24. Our measure of time can be applied 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 distances beyond the confines of the world, where are no bodies at all.

Once the mind has a measure of time, such as the sun’s yearly revolution, it can apply that measure elsewhere. It can measure periods when the measure itself did not exist and had no actual connection with those periods. For example, suppose someone says Abraham was born in the 2712th year of the Julian period. That date is just as understandable as one counted from the beginning of the world. This remains true even though, that far back, there was no movement of the sun or any movement at all. The Julian period is assumed to begin several hundred years before the sun’s revolutions actually marked days, nights, or years. Yet we count just as accurately and measure periods just as well. We do so as if the sun had existed then and moved in the same regular way it does now. We can think of a period equal to one yearly revolution of the sun. We can just as easily APPLY that idea to periods when there was no sun or movement. Similarly, we can take the idea of a foot or yard from bodies here. We can then apply that idea in thought to distances beyond the boundaries of the world, where no bodies exist.

25. As we can measure space in our thoughts where there is no body.

25. Just as we can mentally measure space where there is no physical object.

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.

Suppose the universe’s most distant body were 5639 miles, or millions of miles, from here. Since the universe is finite, that body must be at some definite distance. Similarly, we suppose that 5639 years have passed since any body first existed at the beginning of the world. In our thoughts, we can apply the measure of a year to time before creation. We can also apply it to time beyond the existence of bodies or motion. In the same way, we can apply the measure of a mile to space beyond the farthest bodies. With years, we can mentally measure time where there was no motion. With miles, we can mentally measure space where there is no body.

26. The assumption that the world is neither boundless nor eternal.

26. The assumption that the world is neither infinite 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.

Someone may object that my explanation of time assumes what I should have proved: the world is neither eternal nor infinite. My answer is that, for my present purpose, I need not prove here that the world has limits in time and extent. A limited world is at least as conceivable as an unlimited one. So I am certainly as free to suppose the former as anyone is to suppose the latter. And I have no doubt that anyone who tries can easily imagine a beginning of motion, though not of all duration. In thinking about motion, they may therefore reach a point beyond which they go no further. Similarly, they may imagine limits to bodies and the extent they occupy, but not to space where no bodies exist. The furthest limits of space and duration lie beyond the reach of thought. Likewise, the furthest limits of number exceed even the mind’s greatest powers of comprehension. All these limits lie beyond our grasp for the same reason, as we shall see elsewhere.

27. Eternity.

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.

We therefore gain the idea we call Eternity in the same way, and from the same source, as the idea of time. We gain the ideas of succession and duration by reflecting on the sequence of our own ideas. These ideas arise either naturally, as they continually enter our waking thoughts on their own, or through external objects successively affecting our senses. From the sun’s revolutions, we gain ideas of definite lengths of duration. We can then mentally add these lengths together as often as we please. We can apply the combined lengths to durations in the past or future. We can continue adding without bounds or limits, going on to infinity. We can thus use the length of the sun’s yearly motion to measure duration before the sun or any other motion existed. Doing so is no more difficult or absurd than using today’s sundial to measure how long something lasted last night. For example, I have an idea of the time a shadow takes to move one hour across the sundial today. I can apply that idea to the burning of a candle last night, though that burning is now entirely separate from any actual motion. The candle’s hour of burning last night cannot coexist with any motion happening now or at any future time. Nor can any duration before the world began coexist with the sun’s present motion. Yet I have the IDEA of how long a shadow takes to move between two hour marks on a sundial. With that idea, I can mentally measure how long the candle burned last night as clearly as anything existing now. I need only think of what would have happened if the sun had shone on the sundial then. If the sun had moved at its present rate, the shadow would have passed from one hour mark to another while the candle burned.

28. Our measures of Duration dependent on our ideas.

28. Our ways of measuring duration depend 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.

My notion of an hour, day, or year is simply my idea of how long certain regular, repeating movements last. No such movement ever exists all at once. I have the whole movement only as an idea in my memory, drawn from my senses or reflection. For the same reason, I can just as easily apply this measure in thought to time before any movement existed. I can also apply it to anything a minute or a day before the sun’s movement at this very moment. All past things are equally and completely at rest. Viewed this way, they are all alike, whether they existed before the world began or only yesterday. Measuring how long something lasts by some movement does not depend at all on their REAL existence at the same time. Nor does it depend on that thing existing alongside any other cycle of movement. Instead, I must have a clear IDEA of the length of some known, repeating movement, or another interval of time. I then apply that idea to the duration of the thing I want to measure.

29. The Duration of anything need not be co-existent with the motion we measure it by.

29. The time something lasts need not coincide with the motion used to measure that time.

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.

So we see that some people imagine the world has existed for 5639 years, from its beginning to this present year, 1689. That duration equals 5639 annual revolutions of the sun. Others imagine a much longer duration. For example, in Alexander’s time, the ancient Egyptians counted 23,000 years since the reign of the sun. And the Chinese now count the world as 3,269,000 years old, or more. Although I would not believe their calculations of the world’s greater age, I can imagine that age just as they do. I can also understand those durations and say that one is longer than another. I understand the comparison just as clearly as I understand that Methusalem’s life was longer than Enoch’s. And suppose the usual count of 5639 years is true, as it may be just as well as any other proposed count. Even then, I can still imagine what others mean when they make the world one thousand years older. Anyone can imagine the world being 50,000 years old as easily as 5639. I say imagine, not believe. And anyone can conceive of a duration of 50,000 years as easily as 5639. So, measuring something’s duration by time does not require that thing to exist alongside the motion used to measure it. Nor must that thing exist alongside any other regularly recurring cycle. We need only an idea of the length of ANY regularly recurring event. We can then mentally apply that length to a duration during which the motion or event never occurred.

30. Infinity in Duration.

30. Infinity in Time.

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.

For, as in Moses’ account of creation, I can imagine light existing three days before the sun existed or moved. I need only think of the time light existed before the sun’s creation in the following way. If the sun had moved then as it does now, that time would have equaled three daily revolutions. In the same way, I can imagine chaos or angels being created before any light or continuous motion existed. I can imagine them existing a minute, an hour, a day, a year, or a thousand years earlier. For if I can imagine a minute passing before any body existed or moved, I can add another minute. I can keep adding minutes until I reach sixty. In the same way, I can keep adding minutes, hours, or years without end. These are particular parts of the sun’s revolutions, or of any other period I have an idea of. I can suppose a duration longer than any number of such periods I can count, however long I keep adding. I think this is our notion of eternity. Our notion of eternity’s infinity is no different from our notion of the infinity of numbers. We can keep adding to numbers forever, without end.

31. Origin of our Ideas of Duration, and of the measures of it.

31. Where our ideas of duration and ways to measure duration come from.

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.

So I think the point is clear. Our ideas of duration and how to measure it came from the two sources of all knowledge mentioned earlier: reflection and sensation.

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.

First, we observe what happens in our minds as our ideas continually follow one another. Some ideas disappear, and others begin to appear. From observing these changes, we gain the idea of SUCCESSION. Second, by observing the distance between parts of this succession, we gain 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.

Thirdly, through our senses, we observe certain appearances recurring at regular intervals that seem equally spaced. From these observations, we gain ideas of certain LENGTHS or MEASURES OF DURATION, such as minutes, hours, days, years, etc.

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.

Fourthly, we can mentally repeat measures of time, or ideas of fixed lengths of duration, as often as we wish. By doing so, we can imagine DURATION WHERE NOTHING ACTUALLY LASTS OR EXISTS. In this way, we imagine tomorrow, next year, or seven years from now.

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.

Fifthly, we can repeat in our thoughts the idea of any length of time, such as a minute, year, or age. We can repeat these ideas as often as we like and add them together. We never come any closer to the end of this addition than we do to the end of numbers. We can always add another number. By doing the same with lengths of time, we arrive at the idea of ETERNITY. This includes the endless future existence of our souls, as well as the eternity of that infinite Being. That Being 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.

Sixth, we consider any part of infinite duration as measured by regularly recurring intervals. From this, we form the idea of what we call TIME in general.