rceivable:
and though in extension every the least excess is not so perceptible,
yet the mind has found out ways to examine, and discover
demonstratively, the just equality of two angles, or extensions, or
figures: and both these, i. e. numbers and figures, can be set down by
visible and lasting marks, wherein the ideas under consideration are
perfectly determined; which for the most part they are not, where they
are marked only by names and words.

11. Modes of Qualities not demonstrable like modes of Quantity.

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 of sensations produced 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 of all
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, supposing 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 the proper rotation, which is fit to produce
this sensation of white in us, the more white will that body appear,
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 themselves, as in tasting and feeling, or the impulse
of some sensible particles coming from the