r association of ideas.
When a quality becomes very general, and is common to a great many
individuals, it leads not the mind directly to any one of them; but
by presenting at once too great a choice, does thereby prevent the
imagination from fixing on any single object.

(2) IDENTITY may be esteemed a second species of relation. This relation
I here consider as applied in its strictest sense to constant and
unchangeable objects; without examining the nature and foundation
of personal identity, which shall find its place afterwards. Of all
relations the most universal is that of identity, being common to every
being whose existence has any duration.

(3) After identity the most universal and comprehensive relations are
those of SPACE and TIME, which are the sources of an infinite number of
comparisons, such as distant, contiguous, above, below, before, after,
etc.

(4) All those objects, which admit of QUANTITY, or NUMBER, may be
compared in that particular; which is another very fertile source of
relation.

(5) When any two objects possess the same QUALITY in common, the
DEGREES, in which they possess it, form a fifth species of relation.
Thus of two objects, which are both heavy, the one may be either of
greater, or less weight than the other. Two colours, that are of the
same kind, may yet be of different shades, and in that respect admit of
comparison.

(6) The relation of CONTRARIETY may at first sight be regarded as an
exception to the rule, THAT NO RELATION OF ANY KIND CAN SUBSIST WITHOUT
SOME DEGREE OF RESEMBLANCE. But let us consider, that no two ideas are
in themselves contrary, except those of existence and non-existence,
which are plainly resembling, as implying both of them an idea of the
object; though the latter excludes the object from all times and places,
in which it is supposed not to exist.

(7) All other objects, such as fire and water, heat and cold, are only
found to be contrary from experience, and from the contrariety of their
causes or effects; which relation of cause and effect is a seventh
philosophical relation, as well as a natural one. The resemblance
implied in this relation, shall be explained afterwards.

It might naturally be expected, that I should join DIFFERENCE to the
other relations. But that I consider rather as a negation of relation,
than as anything real or positive. Difference is of two kinds as opposed
either to identity or resemblance. The first is called a differe