'identity'

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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.

BENTHAM'S THEORY OF FICTIONS by Charles Kay Ogden,
London, New York 1932, p. 29.