BOOK I PART III
This operation of the mind, which forms the
belief of any matter of fact, seems hitherto to
have been one of the greatest mysteries of phi-
losophy; though no one has so much as sus-
pected, that there was any difficulty in explain-
us to this conclusion. When we infer the existence of an
object from that of others, some object must always be
present either to the memory or senses, in order to be
the foundation of our reasoning; since the mind cannot
run up with its inferencesin infinitum. Reason can never
satisfy us that the existence of any one object does ever
imply that of another; so that when we pass from the
impression of one to the idea or belief of another, we are
not determined by reason, but by custom or a principle
of association. But belief is somewhat more than a sim-
ple idea. It is a particular manner of forming an idea:
And as the same idea can only be varyed by a variation
of its degrees of force and vivacity; it follows upon the
whole, that belief is a lively idea produced by a relation
to a present impression, according to the foregoing def-
inition.