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. All that is in a man's power in this case is only to observe what the ideas are that take their turns in his Understanding; or else to direct the sort, and call in such as he has a desire or use of; but hinder the constant succession of fresh ones he cannot; though he may commonly choose whether he will heedfully observe and consider them. 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. 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. A good measure of time must divide its whole duration into equal periods. In the measuring of extension there is nothing more required [than] 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." The revolutions of the sun and moon the proper measures of time. 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 accus *See Locke's own parenthetic remark at page 92, first line.—ED. tomed 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 equi-distant spaces of duration, if 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 to the same meridian, and [had] 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? But not by their motion, but periodical appearances.— For the freezing of water or the blowing of a plant, returning at equi-distant periods in all parts of the earth, would as well serve men to reckon their years by, as the motion 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. [Even] a fit of ague, the sense of hunger or thirst, a smell, or a taste, or any other idea returning constantly at equi-distant 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 Cæsar; or [than] many other people, whose years, notwithstanding the motion of the sun, which they pretend 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 Time by periods that had no sensible marks very obvious to distinguish them by. 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 * Dr. Burnet, in his "Theory of the Earth."-ED. 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 [as] that of days was known, or presumed to be so at first; which was only by judging of them by the train of ideas that 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 vvxonμepa,* were guessed to be equal, which was sufficient to make them serve for a measure. Though exact 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 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 course. *For the use of this word, see Nov. Test. Græc, II. Cor. xi. 25—ED. |