in a manner the reflexion of the other; so that all the perceptions of
the mind are double, and appear both as impressions and ideas. When I
shut my eyes and think of my chamber, the ideas I form are exact
representations of the impressions I felt; nor is there any circumstance
of the one, which is not to be found in the other. In running over my
other perceptions, I find still the same resemblance and representation.
Ideas and impressions appear always to correspond to each other. This
circumstance seems to me remarkable, and engages my attention for a
moment.

Upon a more accurate survey I find I have been carried away too far by
the first 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