But
notwithstanding this near resemblance in a few instances, they are in
general so very different, that no-one can make a scruple to rank them
under distinct heads, and assign to each a peculiar name to mark the
difference.(1)
There is another division of our perceptions, which it will be convenient
to observe, and which extends itself both to our impressions and ideas.
This division is into SIMPLE and COMPLEX. Simple perceptions or
impressions and ideas are such as admit of no distinction nor separation.
The complex are the contrary to these, and may be distinguished into
parts. Tho' a particular colour, taste, and smell, are qualities all united
together in this apple, 'tis easy to perceive they are not the same, but are
at least distinguishable from each other.
Having by these divisions given an order and arrangement to our objects,
we may now apply ourselves to consider with the more accuracy their
qualities and relations. The first circumstance, that strikes my eye, is the
great resemblance betwixt our impressions and ideas in every other
particular, except their degree of force and vivacity. The one seem to be 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, tho' 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 tho' 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, 'tis 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
'tis certain he can-not, 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 deriv'd 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 to
any impressions, are obstructed in their operations, as when one is born
blind or deaf; -not only the impressions are lost, but also their