ledge 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.

CHAPTER XV.

IDEAS OF DURATION AND EXPANSION, CONSIDERED TOGETHER.

1. Both capable of greater and less.

Though we have in the precedent chapters dwelt pretty long on the
considerations of space and duration, yet, they being ideas of general
concernment, that have something very abstruse and peculiar in their
nature, the comparing them one with another may perhaps be of use
for their illustration; and we may have the more clear and distinct
conception of them by taking a view of them together. Distance or space,
in its simple abstract conception, to avoid confusion, I call EXPANSION,
to distinguish it from extension, which by some is used to express this
distance only as it is in the solid parts of matter, and so includes, or
at least intimates, the idea of body: whereas the idea of pure distance
includes no such thing. I prefer also the word expansion to space,
because space is often applied to distance of fleeting successive parts,
which never exist together, as well as t