Page:The Works of John Locke - 1823 - vol 01.djvu/255

 Ch. 14. 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 may call an instant, and is that which takes up the time of only one idea in our minds without the succession of another, wherein therefore we perceive no succession at all.

§ 11. This also happens where the motion is so slow as not to supply a constant train of fresh ideas to the senses as fast as the mind is capable of receiving new ones into it; and so other ideas of our own thoughts, having room to come into our minds, between those offered to our senses by the moving body, there the sense of motion is lost; and the body, though it really moves, yet not changing perceivable distance with some other bodies as fast as the ideas of our own minds do naturally follow one another in train, the thing seems to stand still, as is evident in the hands of clocks and shadows of sun-dials, and other constant but slow motions; where, though after certain intervals, we perceive by the change of distance that it hath moved, yet the motion itself we perceive not.

§ 12. So that to me it seems that the constant and regular succession of ideas in a waking man is, as it were, the measure and standard of all other successions: whereof if any one either exceeds the pace of our ideas, as where two sounds or pains, &c. take up in their succession the duration of but one idea, or else where any motion or succession is so slow as that it keeps not pace with the ideas in our minds, or the quickness in which they take their turns; as when any one or more ideas, in their ordinary course, come into our