BOOK I PART III
When the impression of one becomes present
to us, we immediately form an idea of its usual
attendant; and consequently we may establish
this as one part of the definition of an opinion
or belief, that it is an idea related to or associ-
ated with a present impression.
Thus though causation be a philosophical re-
lation, as implying contiguity, succession, and
constant conjunction, yet it is only so far as it
is a natural relation, and produces an union
among our ideas, that we are able to reason
upon it, or draw any inference from it.