_Not sameness of chemical Composition._--Nor does sameness of chemical composition constitute identity. This is merely similarity. Two bodies may be composed of the same chemical elements, in the same proportion, and possessing the same general form and structure, yet they are not the same body. A given piece of wood or iron may be divided into a number of parts, each closely resembling the others, of the same appearance, size, figure, color, weight, and of the same chemical components; yet no one of these is identical with any other. When we say, in such a case, that the different pieces are of the same material, we use the word _same_ with some latitude, to denote, not that they are composed of strictly the same particles, that the substance of the one is the very identical substance of the other, but only that they consist of the same _sort_ or _kind_ of substance, that they are, _e. g._, both wood, or both iron. But this does not constitute identity. There is no limit to the number of identical bodies which it is possible to conceive on this theory of identity. The same power that constructs one body of given chemical elements, and of given form and structure, may make two such, or ten, and if the first two are identical, the ten are, and they may exist at one and the same time, beside each other, identical with each other, yet ten, every one of which is itself, and yet every one is each of the others! _A relative Term._--Identity is a relative term, like most others that are expressive of quality. The term straight implies the idea of that which is not straight; beauty, the idea of deformity; greatness, its opposite; and so of others. Identity stands related to _diversity_ as its opposite. To have the idea of identity, is to have that of diversity also. To affirm the former, is to deny the latter, and to deny is to have the idea of that which is denied. I do not say there can be no _identity_ without diversity, but only that there can be no _idea_ of the one without the idea, also, of the other, any more than there can be the idea of a tall man without the idea of short men. _Opposite of Diversity._--To affirm identity, then, is simply to deny _diversity_, to predicate unity, sameness, oneness. Other objects there are, like this, it may be, similar in every respect, capable of being confounded with it, and mistaken for it, but they are _other_ and not _it_. This we affirm when we affirm identity, _non-diversity_, _non-otherness_. Whatever it be that marks off and distinguishes a thing from all other like or unlike objects--whatever constitutes its _individuality_, its _essence_--_in that consists its identity_.