BOOK I PART IV
bles that perception, which it causes. The re-
lation of cause and effect determines us to join
the other of resemblance; and the ideas of these
existences being already united together in the
fancy by the former relation, we naturally add
the latter to compleat the union. We have a
strong propensity to compleat every union by
joining new relations to those which we have
before observed betwixt any ideas, as we shall
have occasion to observe presently. (Sect. 5.)
Having thus given an account of all the sys-
tems both popular and philosophical, with re-
gard to external existences, I cannot forbear
giving vent to a certain sentiment, which arises
upon reviewing those systems. I begun this
subject with premising, that we ought to have
an implicit faith in our senses, and that this
would be the conclusion, I should draw from