— 535 —
      §11. But in other simple Ideas, whose Modes and Differences are
made, and counted by degrees, and not quantity, we have not so
nice and accurate a distinction of their differences, as to perceive, or
find ways to measure their just Equality or the least Differences.
For those other simple Ideas, being appearances or sensations, pro-
duced in us, by the Size, Figure, Number, and Motion of minute
Corpuscles singly insensible, their different degrees also depend
upon the variation of some, or all of those Causes; which since it
cannot be observed by us in Particles of Matter, whereof each is too
subtile to be perceived, it is impossible for us to have any exact
Measures of the different degrees of these simple Ideas. For suppos-
ing the Sensation or Idea we name Whiteness, be produced in us by a
certain number of Globules, which having a verticity about their
own Centres, strike upon the Retina of the Eye, with a certain
degree of Rotation, as well as progressive Swiftness; it will hence
easily follow, that the more the superficial parts of any Body are so
ordered, as to reflect the greater number of Globules of light, and
to give them that proper Rotation, which is fit to produce this
Sensation of White in us, the more White will that Body appear,
— 536 —
that, from an equal space sends to the Retina the greater number of
such Corpuscles, with that peculiar sort of Motion. I do not say,
that the nature of Light consists in very small round Globules, nor
of Whiteness, in such a texture of parts as gives a certain Rotation
to these Globules, when it reflects them; for I am not now treating
physically of Light, or Colours: But this, I think, I may say, that I
cannot (and I would be glad any one would make intelligible that
he did) conceive how Bodies without us, can any ways affect our
Senses, but by the immediate contact of the sensible Bodies them-
selves, as in Tasting and Feeling, or the impulse of some insensible
Particles coming from them, as in Seeing, Hearing, and Smelling;
by the different impulse of which Parts, caused by their different
Size, Figure, and Motion, the variety of Sensations is
Locke Hum IV, 2, §11, pp. 535-536