fabulous regions, that by the feigned contiguity he may enliven his
imagination.

But though I cannot altogether exclude the relations of resemblance and
contiguity from operating on the fancy in this manner, it is observable
that, when single, their influence is very feeble and uncertain. As the
relation of cause and effect is requisite to persuade us of any real
existence, so is this persuasion requisite to give force to these other
relations. For where upon the appearance of an impression we not only
feign another object, but likewise arbitrarily, and of our mere good-will
and pleasure give it a particular relation to the impression, this can
have but a small effect upon the mind; nor is there any reason, why, upon
the return of the same impression, we should be determined to place the
same object in the same relation to it. There is no manner of necessity
for the mind to feign any resembling and contiguous objects; and if it
feigns such, there is as little necessity for it always to confine itself
to the same, without any difference or variation. And indeed such a
fiction is founded on so little reason, that nothing but pure caprice can
determine the mind to form it; and that principle being fluctuating and
uncertain, it is impossible it can ever operate with any considerable
degree of force and constancy. The mind forsees and anticipates the
change; and even from the very first instant feels the looseness of its
actions, and the weak hold it has of its objects. And as this
imperfection is very sensible in every single instance, it still
encreases by experience and observation, when we compare the several
instances we may remember, and form a general rule against the reposing
any assurance in those momentary glimpses of light, which arise in the
imagination from a feigned resemblance and contiguity.

The relation of cause and effect has all the opposite advantages. The