farthest we can go towards a conception of external objects, when
supposed SPECIFICALLY different from our perceptions, is to form a
relative idea of them, without pretending to comprehend the related
objects. Generally speaking we do not suppose them specifically
different; but only attribute to them different relations, connections
and durations. But of this more fully hereafter.[Part IV, Sect. 2.]

PART III. OF KNOWLEDGE AND PROBABILITY.

SECT. I. OF KNOWLEDGE.

There are seven [Part I. Sect. 5.] different kinds of philosophical
relation, viz. RESEMBLANCE, IDENTITY, RELATIONS OF TIME AND PLACE,
PROPORTION IN QUANTITY OR NUMBER, DEGREES IN ANY QUALITY, CONTRARIETY
and CAUSATION. These relations may be divided into two classes; into
such as depend entirely on the ideas, which we compare together, and
such as may be changed without any change in the ideas. It is from the
idea of a triangle, that we discover the relation of equality, which its
three angles bear to two right ones; and this relation is invariable,
as long as our idea remains the same. On the contrary, the relations of
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