An Enquiry Concerning Human Understanding | Page 7

and augmenting, without limit, those qualities of goodness and wisdom. We
may prosecute this enquiry to what length we please; where we shall always find, that
every idea which we examine is copied from a similar impression. Those who would
assert that this position is not universally true nor without exception, have only one, and
that an easy method of refuting it; by producing that idea, which, in their opinion, is not
derived from this source. It will then be incumbent on us, if we would maintain our
doctrine, to produce the impression, or lively perception, which corresponds to it.
15. Secondly. If it happen, from a defect of the organ, that a man is not susceptible of any
species of sensation, we always find that he is as little susceptible of the correspondent
ideas. A blind man can form no notion of colours; a deaf man of sounds. Restore either of
them that sense in which he is deficient; by opening this new inlet for his sensations, you
also open an inlet for the ideas; and he finds no difficulty in conceiving these objects. The
case is the same, if the object, proper for exciting any sensation, has never been applied
to the organ. A Laplander or Negro has no notion of the relish of wine. And though there
are few or no instances of a like deficiency in the mind, where a person has never felt or
is wholly incapable of a sentiment or passion that belongs to his species; yet we find the
same observation to take place in a less degree. A man of mild manners can form no idea
of inveterate revenge or cruelty; nor can a selfish heart easily conceive the heights of
friendship and generosity. It is readily allowed, that other beings may possess many
senses of which we can have no conception; because the ideas of them have never been
introduced to us in the only manner by which an idea can have access to the mind, to wit,
by the actual feeling and sensation.
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,