of that colour in the external object
may be only a privation.

4. Why a privative cause in nature may occasion a positive idea.

If it were the design of my present undertaking to inquire into the
natural causes and manner of perception, I should offer this as a reason
why a privative cause might, in some cases at least, produce a positive
idea; viz. that all sensation being produced in us only by different
degrees and modes of motion in our animal spirits, variously agitated by
external objects, the abatement of any former motion must as necessarily
produce a new sensation as the variation or increase of it; and so
introduce a new idea, which depends only on a different motion of the
animal spirits in that organ.

5. Negative names need not be meaningless.

But whether this be so or not I will not here determine, but appeal
to every one's own experience, whether the shadow of a man, though it
consists of nothing but the absence of light (and the more the absence
of light is, the more discernible is the shadow) does not, when a man
looks on it, cause as clear and positive idea in his mind, as a man
himself, though covered over with clear sunshine? And the picture of a
shadow is a positive thing. Indeed, we have negative names, to which
there be no positive ideas; but they consist wholly in negation of some
certain ideas, as SILENCE, INVISIBLE; but these signify not any ideas in
the mind but their absence.

6. Whether any ideas are due to causes really private.

And thus one may truly be said to see darkness. For, supposing a hole
perfectly dark, from whence no light is reflected, it is certain one may
see the figure of it, or it may be painted; or whether the ink I write
with makes any other idea, is a question. The privative causes I have
here assigned of positive ideas are according to the common opinion;
but, in truth, it will be hard to determine whether there be really any
ideas from a privative cause, till it be determined, whether rest be any
more a privation than motion.

7. Ideas in the Mind, Qualities in Bodies.

To discover the nature of our IDEAS the better, and to, discourse of
them intelligibly, it will be convenient to distinguish them AS THEY
ARE IDEAS OR PERCEPTIONS IN OUR MINDS; and AS THEY ARE MODIFICATIONS OF
MATTER IN THE BODIES THAT CAUSE SUCH PERCEPTIONS IN US: that so we may
not think (as perhaps usually is done) that they are exactly the images
and resemblances of something inh