and
ideas, which differ from each other only in their different degrees
of force and vivacity. Our ideas are copyed from our impressions, and
represent them in all their parts. When you would any way vary the idea
of a particular object, you can only encrease or diminish its force and
vivacity. If you make any other change on it, it represents a different
object or impression. The case is the same as in colours. A particular
shade of any colour may acquire a new degree of liveliness or brightness
without any other variation. But when you produce any other variation,
it is no longer the same shade or colour. So that as belief does nothing
but vary the manner, in which we conceive any object, it can only bestow
on our ideas an additional force and vivacity. An opinion, therefore,
or belief may be most accurately defined, a lively idea related to or
associated with a present impression.

We may here take occasion to observe a very remarkable error, which
being frequently inculcated in the schools, has become a kind of
establishd maxim, and is universally received by all logicians. This
error consists in the vulgar division of the acts of the understanding,
into CONCEPTION, JUDGMENT and REASONING, and in the definitions we give
of them. Conception is defind to be the simple survey of one or more
ideas: Judgment to be the separating or uniting of different ideas:
Reasoning to be the separating or uniting of different ideas by the
interposition of others, which show the relation they bear to each
other. But these distinctions and definitions are faulty in very
considerable articles. For FIRST, it is far from being true, that in
every judgment, which we form, we unite two different ideas; since in
that proposition, GOD IS, or indeed any other, which regards existence,
the idea of existence is no distinct idea, which we unite with that
of the object, and which is capable of forming a compound idea by the
union. SECONDLY, As we can thus form a proposition, which contains only
one idea, so we may exert our reason without employing more than two
ideas, and without having recourse to a third to serve as a medium
betwixt them. We infer a cause immediately from its effect; and this
inference is not only a true species of reasoning, but the strongest of
all others, and more convincing than when we interpose another idea to
connect the two extremes. What we may in general affirm concerning these
three acts of the understanding is, that