BOOK I PART III
SECTIONXIV. OF THEIDEA OFNECESSARY
CONNEXION
Having thus explained the manner, in which
we reason beyond our immediate impressions,
and conclude that such particular causes must
have such particular effects; we must now re-
turn upon our footsteps to examine that ques-
tion, which (Sect. 2.) first occured to us, and
which we dropt in our way, viz. What is our
idea of necessity, when we say that two objects
are necessarily connected together. Upon this
head I repeat what I have often had occasion to
observe, that as we have no idea, that is not de-
rived from an impression, we must find some
impression, that gives rise to this idea of neces-
sity, if we assert we have really such an idea.
In order to this I consider, in what objects ne-
cessity is commonly supposed to lie; and find-