| (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 difference of number; the other of KIND. |
| SECT. VI. OF MODES AND SUBSTANCES |
| I would fain ask those philosophers, who found so much of their reasonings on the distinction of substance and accident, and imagine we have clear ideas of each, whether the idea of substance be derived from the impressions of sensation or of reflection? If it be conveyed to us by our senses, I ask, which of them; and after what manner? If it be perceived by the eyes, it must be a colour; if by the ears, a sound; if by the palate, a taste; and so of the other senses. |
| But I believe none will assert, that substance is either a colour, or sound, or a taste. |
| The idea, of substance must therefore be derived from an impression of reflection, if it really exist. |
| But the impressions of reflection resolve themselves into our passions and emotions: none of which can possibly represent a substance. |