16. There is, however, one contradictory phenomenon, which may prove
that it is not absolutely impossible for ideas to arise, independent
of their correspondent impressions. I believe it will readily be
allowed, that the several distinct ideas of colour, which enter by the
eye, or those of sound, which are conveyed by the ear, are really
different from each other; though, at the same time, resembling. Now
if this be true of different colours, it must be no less so of the
different shades of the same colour; and each shade produces a
distinct idea, independent of the rest. For if this should be
denied, it is possible, by the continual gradation of shades, to run a
colour insensibly into what is most remote from it; and if you will
not allow any of the means to be different, you cannot, without
absurdity, deny the extremes to be the same. Suppose, therefore, a
person to have enjoyed his sight for thirty years, and to have
become perfectly acquainted with colours of all kinds except one
particular shade of blue, for instance, which it never has been his
fortune to meet with. Let all the different shades of that colour,
except that single one, be placed before him, descending gradually
from the deepest to the lightest; it is plain that he will perceive
a blank, where that shade is wanting, and will be sensible that
there is a greater distance in that place between the contiguous
colours than in any other. Now I ask, whether it be possible for
him, from his own imagination, to supply this deficiency, and raise up
to himself the idea of that particular shade, though it had never been
conveyed to him by his senses? I believe there are few but will be
of opinion that he can: and this may serve as a proof that the
simple ideas are not always, in every instance, derived from the
correspondent impressions; though this instance is so singular, that
it is scarcely worth our observing, and does not merit that for it
alone we should alter our general maxim.

17. Here, therefore, is a proposition, which not only seems, in
itself, simple and intelligible; but, if a proper use were made of it,
might render every dispute equally intelligible, and banish all that
jargon, which has so long taken possession of metaphysical reasonings,
and drawn disgrace upon them. All ideas, especially abstract ones, are
naturally faint and obscure: the mind has but a slender hold of
them: they are apt to be confounded with other resembling ideas; and
when we have often employed any term, though without a distinct
meaning, we are apt to imagine it has a determinate idea annexed to
it. On the contrary, all impressions, that is, all sensations,
either outward or inward, are strong and vivid: the limits between
them are more exactly determined: nor is it easy to fall into any
error or mistake with regard to them. When we entertain, therefore,
any suspicion that a philosophical term is employed without any
meaning or idea (as is but too frequent), we need but enquire, from
what impression is that supposed idea derived? And if it be impossible
to assign any, this will serve to confirm our suspicion. By bringing
ideas into so clear a light we may reasonably hope to remove all
dispute, which may arise, concerning their nature and reality.*
* It is probable that no more was meant by those, who denied
innate ideas, than that all ideas were copies of our impressions;
though it must be confessed, that the terms, which they employed, were
not chosen with such caution, nor so exactly defined, as to prevent
all mistakes about their doctrine. For what is meant by innate? If
innate be equivalent to natural, then all the perceptions and ideas of
the mind must be allowed to be innate or natural, in whatever sense we
take the latter word, whether in opposition to what is uncommon,
artificial, or miraculous. If by innate be meant, contemporary to
our birth, the dispute seems to be frivolous; nor is it worth while to
enquire at what time thinking begins, whether before, at, or after our
birth. Again, the word idea, seems to be commonly taken in a very
loose sense, by Locke and others; as standing for any of our
perceptions, our sensations and passions, as well as thoughts. Now
in this sense, I should desire to know, what can be meant by
asserting, that self-love, or resentment of injuries, or the passion
between the sexes is not innate?
But admitting these terms, impressions and ideas, in the sense above
explained, and understanding by innate, what is original or copied
from no precedent perception, then may we assert that all our
impressions are innate, and our ideas not innate