om the constant union of
causes and effects, according to past experience and observation.

In accompts of any length or importance, Merchants seldom trust to
the infallible certainty of numbers for their security; but by the
artificial structure of the accompts, produce a probability beyond what
is derived from the skill and experience of the accomptant. For that
is plainly of itself some degree of probability; though uncertain and
variable, according to the degrees of his experience and length of
the accompt. Now as none will maintain, that our assurance in a long
numeration exceeds probability, I may safely affirm, that there scarce
is any proposition concerning numbers, of which we can have a fuller
security. For it is easily possible, by gradually diminishing the
numbers, to reduce the longest series of addition to the most simple
question, which can be formed, to an addition of two single numbers; and
upon this supposition we shall find it impracticable to shew the precise
limits of knowledge and of probability, or discover that particular
number, at which the one ends and the other begins. But knowledge and
probability are of such contrary and disagreeing natures, that they
cannot well run insensibly into each other, and that because they will
not divide, but must be either entirely present, or entirely absent.
Besides, if any single addition were certain, every one would be so, and
consequently the whole or total sum; unless the whole can be different
from all its parts. I had almost said, that this was certain; but I
reflect that it must reduce itself, as well as every other reasoning,
and from knowledge degenerate into probability.

Since therefore all knowledge resolves itself into probability, and
becomes at last of the same nature with that evidence, which we employ
in common life, we must now examine this latter species of reasoning,
and see on what foundation it stands.

In every judgment, which we can form concerning probability, as well
as concerning knowledge, we ought always to correct the first judgment,
derived from the nature of the object, by another judgment, derived from
the nature of the understanding. It is certain a man of solid sense and
long experience ought to have, and usually has, a greater assurance
in his opinions, than one that is foolish and ignorant, and that our
sentiments have different degrees of authority, even with ourselves, in
proportion to the degrees of our reason and exp