s to follow one another
immediately in our minds, we have no perception of motion; which
consisting in a constant succession, we cannot perceive that succession
without a constant succession of varying ideas arising from it.

8. Very swift motions unperceived.

On the contrary, things that move so swift as not to affect the senses
distinctly with several distinguishable distances of their motion, and
so cause not any train of ideas in the mind, are not also perceived.
For anything that moves round about in a circle, in less times than our
ideas are wont to succeed one another in our minds, is not perceived to
move; but seems to be a perfect entire circle of the matter or colour,
and not a part of a circle in motion.

9. The Train of Ideas has a certain Degree of Quickness.

Hence I leave it to others to judge, whether it be not probable that
our ideas do, whilst we are awake, succeed one another in our minds
at certain distances; not much unlike the images in the inside of a
lantern, turned round by the heat of a candle. This appearance of theirs
in train, though perhaps it may be sometimes faster and sometimes
slower, yet, I guess, varies not very much in a waking man: there seem
to be certain bounds to the quickness and slowness of the succession of
those ideas one to another in our minds, beyond which they can neither
delay nor hasten.

10. Real succession in swift motions without sense of succession.

The reason I have for this odd conjecture is, from observing that, in
the impressions made upon any of our senses, we can but to a certain
degree perceive any succession; which, if exceeding quick, the sense of
succession is lost, even in cases where it is evident that there is a
real succession. Let a cannon-bullet pass through a room, and in its way
take with it any limb, or fleshy parts of a man, it is as clear as any
demonstration can be, that it must strike successively the two sides of
the room: it is also evident, that it must touch one part of the flesh
first, and another after, and so in succession: and yet, I believe,
nobody who ever felt the pain of such a shot, or heard the blow against
the two distant walls, could perceive any succession either in the pain
or sound of so swift a stroke. Such a part of duration as this, wherein
we perceive no succession, is that which we call an INSTANT, and is
that which takes up the time of only one idea in our minds, without the
succession of another; wherein