of ourselves, or any such other
thing co-existent with our thinking.

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

5. The Idea of Duration applicable to Things whilst 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 duratio