ence of the
same thing, as that it is a foot square, or lasted two years; the other
shows the distance of it in place, or existence from other fixed points
of space or duration, as that it was in the middle of Lincoln's Inn
Fields, or the first degree of Taurus, and in the year of our Lord 1671,
or the 1000th year of the Julian period. All which distances we measure
by preconceived ideas of certain lengths of space and duration,--as
inches, feet, miles, and degrees, and in the other, minutes, days, and
years, &c.

9. All the Parts of Extension are Extension, and all the Parts of
Duration are Duration.

There is one thing more wherein space and duration have a great
conformity, and that is, though they are justly reckoned amongst 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 of them
to consist of parts: but their parts being all of the same kind, and
without the mixture of any other idea, hinder them not from having a
place amongst simple ideas. Could the mind, as in number, come to so
small a part of extension or duration as excluded divisibility, THAT
would be, as it were, the indivisible unit or idea; by repetition of
which, it would make its more enlarged ideas of extension and duration.
But, since the mind is not able to frame an idea of ANY space without
parts, instead thereof it makes use of the common measures, which, by
familiar use in each country, have imprinted themselves on the memory
(as inches and feet; or cubits and parasangs; and so seconds, minutes,
hours, days, and years in duration);--the mind makes use, I say, of
such ideas as these, as simple ones: and these are the component parts
of larger ideas, which the mind upon occasion makes by the addition of
such known lengths which it is acquainted with. On the other side, the
ordinary smallest measure we have of either is looked on as an unit in
number, when the mind by division would reduce them into less fractions.
Though on both sides, both in addition and division, either of space or
duration, when the idea under consideration becomes very big or very
small, its precise bulk becomes very obscure and confused; and it is the
NUMBER of its repeated additions or divisions that alone remains clear
and distinct; as will easily appear to any one who will let his thoughts
loose in the vast expansion of space, or divisibility of matter. Every
part of duration is durat