contiguity and distance betwixt two objects may be changed merely by an
alteration of their place, without any change on the objects themselves
or on their ideas; and the place depends on a hundred different
accidents, which cannot be foreseen by the mind. It is the same case with
identity and causation. Two objects, though perfectly resembling each
other, and even appearing in the same place at different times, may be
numerically different: And as the power, by which one object produces
another, is never discoverable merely from their idea, it is evident cause
and effect are relations, of which we receive information from
experience, and not from any abstract reasoning or reflection. There is
no single phaenomenon, even the most simple, which can be accounted for
from the qualities of the objects, as they appear to us; or which we
coued foresee without the help of our memory and experience.

It appears, therefore, that of these seven philosophical relations, there
remain only four, which depending solely upon ideas, can be the objects
of knowledge said certainty. These four are RESEMBLANCE, CONTRARIETY,
DEGREES IN QUALITY, and PROPORTIONS IN QUANTITY OR NUMBER. Three of these
relations are discoverable at first sight, and fall more properly under
the province of intuition than demonstration. When any objects resemble
each other, the resemblance will at first strike the eve, or rather the
mind; and seldom requires a second examination. The case is the same with
contrariety, and with the degrees of any quality. No one can once doubt
but existence and non-existence destroy each other, and are perfectly
incompatible and contrary. And though it be impossible to judge exactly of
the degrees of any quality, such as colour, taste, heat, cold, when the
difference betwixt them is very small: yet it is easy to decide, that any
of them is superior or inferior to another, when their difference is
considerable. And this decision we always pronounce at first sight,
without any enquiry or reasoning.