73. When it is said that the idea of identity, or of any other relation, is formed upon consideration of things as existing in a certain way, this is naturally understood to mean--indeed, otherwise it is unmeaning--that the things are first _known_ as existing, and that afterwards the idea of the relation in question is formed. But according to Locke, as we have seen, [1] the first and simplest act of knowledge possible is the perception of identity between ideas. Either then the ‘things,’ upon consideration of which the idea of identity is formed, are not known at all, or the knowledge of them involves the very idea afterwards formed on consideration of them. Locke, having at whatever cost of self-contradiction to make his theory fit the exigencies of language, virtually adopts the latter alternative, though with an ambiguity of expression which makes a definite meaning difficult to elicit. We have, however, the positive statement to begin with, that the comparison in which the relation originates, is of a thing with itself as existing at another time. Again, the ‘ideas’ (used interchangeably with ‘things’), to which identity is attributed, ‘vary not at all from what they were at that moment wherein we consider their former existence.’ It is here clearly implied that ‘things’ or ‘ideas’ _exist_, _i.e._ are given to us in the spontaneous consciousness which we do not make, as each one and the same throughout a multiplicity of times. This, again, means that the relation of identity or sameness, _i.e._ unity of thing under multiplicity of appearance, belongs to or consists in the ‘very being’ of those given objects of consciousness, which are in Locke’s sense the real, and upon which according to him all relation is superinduced by an after-act of thought. So long as each such object ‘continues to exist,’ so long its ‘sameness with itself must continue,’ and this sameness is the complex idea, the relation, of identity. Just as before, following Locke’s lead, we found the simple idea, as the element of knowledge, become complex--a perceived identity of ideas; so now mere existence, the ‘very being of things’ (which with Locke is only another name for the simple idea), resolves itself into a relation, which it requires ‘consideration by the mind’ to constitute. [1] See above, paragraph 25. Locke fails to distinguish between identity and mere unity.