No two entities of any kind can present themselves simultaneously to the mind—no, nor can so much as the same object present itself at different times—without presenting the idea of Relation. For relation is a fictitious entity, which is produced, and has place, as often as the mind, having perception of any one object, obtains, at the same, or at any immediately succeeding instant, perception of any other object, or even of that same object, if the perception be accompanied with the perception of its being the same : Diversity is, in the one case, the name of the relation. Identity is, in the other case. But, as identity is but the negation of diversity, thence if, on no occasion, diversity had ever been, neither, on any occasion, would any such idea as that of identity have come into existence.
Whatsoever two entities, real or fictitious, come to receive names, and thus to receive their nominal existence, Relation would be the third ; for, between the two—they being, by the supposition, different, and both of them actual objects of perception—the relation of difference or diversity would also become an object of perception, and in the character of a fictitious entity, a production of the acts of abstractions and denomination, acquire its nominal existence.
Next, after matter and form the fictitious entity relation, or the class of fictitious entities called Relations, might, therefore, have been brought to view. But not only between matter and form, but also between the one and the other respectively, and the fictitious entities designated by the words quantity, space, and quality, so close seemed the connexion as not to be, without sensible inconvenience, broken by the interposition of any other.
Once introduced upon the carpet, the fictitious entity called relation swells into an extent such as to swallow up all the others. Every other fictitious entity is seen to be but a mode of this.
The most extensive, and, in its conception, simple of all relations—i.e. of all modes or modifications of the fictitious entity, denominated relation—is that of place, with its submodifications.
Next to that in the order of simplicity comes the modification of time, with its submodifications.
Next to them come successively the relations designated by the several words, Motion, rest, action, passion. Subalternation, viz. logical subalternation, opposition, and connexion, or the relation between cause and effect.
Existence, with its several modifications, or correspondent fictitious entities—non-existence, futurity, actuality, potentiality, necessity, possibility, and impossibility—will, with most convenience, close the rear. Though still more extensive than even relation, they could not be brought to view before it, being applicable to all other relations—to relations of all sorts, and in a word, to entities, whether fictitious or real, of all sorts—no complete, or so much as correct view of their nature and character could be given, till these less extensive ones had been brought to view.