or shadows of sun-dials on account of their slowness. We may call an instant that part of duration wherein we perceive no succession;`or which takes up the time of only one idea in our minds. From my own experience, I think no one can keep one unvaried single idea a long time in his mind. The consideration of Duration as set out by certain periods and marked by certain measures or epochs, is that which most properly we call time. We cannot measure duration as we can extension, by the application of one part of it to another: nothing can serve well for a convenient measure of time, but what has the whole length of its duration divided into appa-rently equal portions, by constantly repeated periods: for this reason the annual and diurnal revolutions of the sun and moon have been the common measures. The distinction of days and years depending on the motion of the sun, some have falsely thought that motion and duration were the measure one of the other, and that time and motion had a necessary connexion whereas any constant periodical appearance or alteration of ideas in equidistant spaces of duration, if constant and universally observable, would have served as well.

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 can make use of can be known to do so: since no two portions of suc

cession can be brought together, it is impossible certainly to know their equality.

Having got a measure of time, we can apply it to duration, antecedent to the existence of the measure itself; thus we can apply the measure of a year to duration before the creation. We may easily conceive the beginning of motion, but not of duration: and in our thoughts we may set limits to body, but not to space.

We get the Idea of Eternity by the same means as that of Time; having got the Idea of succession and duration we can in imagination add certain lengths of duration together as often as we please, without limit.

CHAP. XV.

OF DURATION AND EXPANSION CONSIDERED

TOGETHER.

DISTANCE or space, abstractedly, I call

expansion, to distinguish it from extension, which by some is only applied to matter: and I prefer expansion to space, because Space is often applied to distance of fleeting successive parts which never exist together,

as well as to those which are permanent. In expansion and duration, the mind has this common idea of continued lengths capable of greater or less quantities having as clear an idea of the difference of length between an hour and a day, as between an inch and a foot. We can easily conceive the end of extension but not of expansion. It is arrogant to say, that beyond the bounds of body there is nothing; confining God within the limits of matter.-Though we easily admit duration boundless, as it certainly is, we cannot extend it beyond all being; we easily allow that God fills eternity; and why not, that he fills immensity? It is ascribing too much to matter, to say, where there is no body, there is nothing.. The idea of infinite duration is more easily admitted, than of infinite expansion; for we consider the first as an attribute of God; but (attributing extension only to matter, which is finite,) we are apt to doubt of the existence of expansion without matter, as if the confines 'of body and space were the same. The names of things may direct us to the origin of men's ideas; and from the term duration, one may suppose, that the continuation of existence, with a kind of resistance to destructive force, was thought to have some analogy to the continuation of solidity, which is apt to be confounded with hardness.-Hence durure and durum esse; that durare is applied to the idea of hardness as well as of existence, we see

in Horace, Ep. 16. ferro duravit sæcula.-Time in general is to duration, what place is to expansion; a landmark to denote the relative position of finite existences. Where and when are questions belonging to all finite existences. Space and Duration have a great conformity in this,-that, though justly reckoned among our simple Ideas, yet none of the distinct ideas we have of either is without all manner of composition: it is the very nature of both to consist of parts; but their parts are all of the same kind, without the mixture of any other idea. The mind cannot as in number, come to an indivisible unit, or idea, and conceive space without parts; it therefore uses the common measures of inches, feet, hours, days, as simple ideas of which larger ones are compounded. They agree also in this, that considered as having parts, yet their parts are not separable even in thought.- Duration is as a line, extended in infinitum; not capable of variation or figure: Expansion, as a solid, admitting of straight lines through it in every direction. It is nearly as hard for us to conceive any real being without expansion as without duration; what spirits therefore have to do with space or how they communicate in it, we know not: we only know that each body possesses its proper portion, to the exclusion of all others.--Duration, is the idea we have of perishing distance, no two parts of which exist together: Expansion is the idea of

lasting distance, all the parts of which exist together. Though we cannot conceive duration without succession, that is, that the being of this moment is the being of any future one; yet we can conceive the eternal duration of the Almighty, because he has infinite knowledge even of things future.-The distinct ideas of expansion and duration singularly combine, every part of each being in every part of the other.

CHAP. XVI.

OF NUMBER.

NUMBER is the simplest and most universal Idea we have. Every object of our senses, and thought of our minds, brings this idea with it. All our complex ideas of its modes are formed by the simple addition of the idea of Unity to itself: its modes too are the most distinct, each combination being as clearly distinct from that nearest to it as from the most remote: but in other simple modes two approaching ideas, though really different, are not easily distinguished; as is clear from the colour and extension of bodies, where real minute differences do not give us distinct ideas.

This distinctness of its modes makes the demon