A Treatise of Human Nature | Page 6

appearance, and that I must make use of the distinction of perceptions into simple and
complex, to limit this general decision, that all our ideas and impressions are resembling.
I observe, that many of our complex ideas never had impressions, that corresponded to
them, and that many of our complex impressions never are exactly copied in ideas. I can
imagine to myself such a city as the New Jerusalem, whose pavement is gold and walls
are rubies, though I never saw any such. I have seen Paris; but shall I affirm I can form
such an idea of that city, as will perfectly represent all its streets and houses in their real
and just proportions?
I perceive, therefore, that though there is in general a great, resemblance betwixt our
complex impressions and ideas, yet the rule is not universally true, that they are exact
copies of each other. We may next consider how the case stands with our simple,
perceptions. After the most accurate examination, of which I am capable, I venture to
affirm, that the rule here holds without any exception, and that every simple idea has a
simple impression, which resembles it, and every simple impression a correspondent idea.
That idea of red, which we form in the dark, and that impression which strikes our eyes in
sun-shine, differ only in degree, not in nature. That the case is the same with all our
simple impressions and ideas, it is impossible to prove by a particular enumeration of
them. Every one may satisfy himself in this point by running over as many as he pleases.
But if any one should deny this universal resemblance, I know no way of convincing him,
but by desiring him to shew a simple impression, that has not a correspondent idea, or a
simple idea, that has not a correspondent impression. If he does not answer this challenge,
as it is certain he cannot, we may from his silence and our own observation establish our
conclusion.

Thus we find, that all simple ideas and impressions resemble each other; and as the
complex are formed from them, we may affirm in general, that these two species of
perception are exactly correspondent. Having discovered this relation, which requires no
farther examination, I am curious to find some other of their qualities. Let us consider
how. they stand with regard to their existence, and which of the impressions and ideas are
causes, and which effects.
The full examination of this question is the subject of the present treatise; and therefore
we shall here content ourselves with establishing one general proposition, THAT ALL
OUR SIMPLE IDEAS IN THEIR FIRST APPEARANCE ARE DERIVED FROM
SIMPLE IMPRESSIONS, WHICH ARE CORRESPONDENT TO THEM, AND
WHICH THEY EXACTLY REPRESENT.
In seeking for phenomena to prove this proposition, I find only those of two kinds; but in
each kind the phenomena are obvious, numerous, and conclusive. I first make myself
certain, by a new, review, of what I have already asserted, that every simple impression is
attended with a correspondent idea, and every simple idea with a correspondent
impression. From this constant conjunction of resembling perceptions I immediately
conclude, that there is a great connexion betwixt our correspondent impressions and ideas,
and that the existence of the one has a considerable influence upon that of the other. Such
a constant conjunction, in such an infinite number of instances, can never arise from
chance; but clearly proves a dependence of the impressions on the ideas, or of the ideas
on the impressions. That I may know on which side this dependence lies, I consider the
order of their first appearance; and find by constant experience, that the simple
impressions always take the precedence of their correspondent ideas, but never appear in
the contrary order. To give a child an idea of scarlet or orange, of sweet or bitter, I
present the objects, or in other words, convey to him these impressions; but proceed not
so absurdly, as to endeavour to produce the impressions by exciting the ideas. Our ideas
upon their appearance produce not their correspondent impressions, nor do we perceive
any colour, or feel any sensation merely upon thinking of them. On the other hand we
find, that any impression either of the mind or body is constantly followed by an idea,
which resembles it, and is only different in the degrees of force and liveliness, The
constant conjunction of our resembling perceptions, is a convincing proof, that the one
are the causes of the other; and this priority of the impressions is an equal proof, that our
impressions are the causes of our ideas, not our ideas of our, impressions.
To confirm this I consider Another plain and convincing phaenomenon; which is, that,
where-ever by any accident the faculties, which give rise