of our ideas. Where an
opinion admits of no doubt, or opposite probability, we attribute to it
a full conviction: though the want of resemblance, or contiguity, may
render its force inferior to that of other opinions. It is thus the
understanding corrects the appearances of the senses, and makes us
imagine, that an object at twenty foot distance seems even to the eye as
large as one of the same dimensions at ten.

We may observe the same effect of poetry in a lesser degree; only with
this difference, that the least reflection dissipates the illusions
of poetry, and Places the objects in their proper light. It is however
certain, that in the warmth of a poetical enthusiasm, a poet has a
counterfeit belief, and even a kind of vision of his objects: And
if there be any shadow of argument to support this belief, nothing
contributes more to his full conviction than a blaze of poetical figures
and images, which have their effect upon the poet himself, as well as
upon his readers.

SECT. XI. OF THE PROBABILITY OF CHANCES.

But in order to bestow on this system its full force and evidence, we
must carry our eye from it a moment to consider its consequences, and
explain from the same principles some other species of reasoning, which
are derived from the same origin.

Those philosophers, who have divided human reason into knowledge and
probability, and have defined the first to be that evidence, which
arises from the comparison of ideas, are obliged to comprehend all our
arguments from causes or effects under the general term of probability.
But though every one be free to use his terms in what sense he pleases;
and accordingly in the precedent part of this discourse, I have followed
this method of expression; it is however certain, that in common
discourse we readily affirm, that many arguments from causation exceed
probability, and may be received as a superior kind of evidence. One
would appear ridiculous, who would say, that it is only probable the
sun will rise to-morrow, or that all men must dye; though it is plain we
have no further assurance of these facts, than what experience affords
us. For this reason, it would perhaps be more convenient, in order at
once to preserve the common signification of words, and mark the several
degrees of evidence, to distinguish human reason into three kinds, viz.
THAT FROM KNOWLEDGE, FROM PROOFS, AND FROM PROBABILITIES. By knowledge,
I mean the assurance arising from the compa