minds: that, for this reason, when we sleep soundly without
dreaming, we have no perception of time, or the length of it whilst
we sleep; and that the moment wherein we leave off to think, till
the moment we begin to think again, seems to have no distance." To
which the author adds, "and so I doubt not but 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."

We might carry this thought further, and consider a man as on one
side, shortening his time by thinking on nothing, or but a few
things; so, on the other, as lengthening it, by employing his
thoughts on many subjects, or by entertaining a quick and constant
succession of ideas. Accordingly, Monsieur Malebranche, in his
"Inquiry after Truth," which was published several years before Mr.
Locke's Essay on "Human Understanding," tells us, "that it is
possible some creatures may think half an hour as long as we do a
thousand years; or look upon that space of duration which we call a
minute, as an hour, a week, a month, or a whole age."

This notion of Monsieur Malebranche is capable of some little
explanation from what I have quoted out of Mr. Locke; for if our
notion of time is produced by our reflecting on the succession of
ideas in our mind, and this succession may be infinitely accelerated
or retarded, it will follow that different beings may have different
notions of the same parts of duration, according as their ideas,