m, 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
produced in us.

12. Particles of light and simple ideas of colour.

Whether then they be globules or no; or whether they have a verticity
about their own centres that produces the idea of whiteness in us; this
is certain, that the more particles of light are reflected from a body,
fitted to give them that peculiar motion which produces the sensation
of whiteness in us; and possibly too, the quicker that peculiar motion
is,--the whiter does the body appear from which the greatest number are
reflected, as is evident in the same piece of paper put in the sunbeams,
in the shade, and in a dark hole; in each of which it will produce in us
the idea of whiteness in far different degrees.

13. The secondary Qualities of things not discovered by Demonstration.

Not knowing, therefore, what number of particles, nor what motion of
them, is fit to produce any precise degree of whiteness, we cannot
DEMONSTRATE the certain equality of any two degrees of whiteness;
because we have no certain standard to measure them by, nor means to
distinguish every the least real difference, the only help we have being
from our senses, which in this point fail us. But where the difference
is so great as to produce in the mind clearly distinct ideas, whose
differences can be perfectly retained, there these ideas or colours,
as we see in different kinds, as blue and red, are as capable of
demonstration as ideas of number and extension. What I have here said of
whiteness and colours, I think holds true in all secondary qualities and
their modes.

14. III. Sensitive Knowledge of the particular Existence of finite
beings without us.

These two, viz. intuition and demonstration, are the degrees of our
KNOWLEDGE; whatever comes short of one of these, with what assurance
soever embraced, is but FAITH or OPINION, but not knowledge, at least in
all general truths. There is, indeed, another perception of the mind,
employed about THE PARTICULAR EXISTENCE OF FINITE BEINGS WITHOUT US,
which, going beyond bare probability, and yet not reaching perfectly to
either of the foregoing degrees of certainty, passes under the name
of KNOWLEDGE. There can be nothing more certain than that the idea we
receive from an external object is in our minds: this is intuitive
knowledge. But whether there be any