Sameness, accordingly, depends upon a special purpose. If in a chemical combination a metal is wanted, it may be all the same whether we use iron, zinc, lead, or gold. That is to say, it is all the same for bringing about a special result; yet it is not all the same in other respects. The weight and certain other qualities of the metals are different, and also the cost. SAMENESS AND MIND. Sameness depending upon a special purpose, the question arises, Is there any objective sameness in the world, or is sameness a mere subjective addition to things? Is sameness something “real” or is it purely mental? This is the old quarrel between the Nominalists and Realists among the Schoolmen. It lies at the bottom of the problem of universals and particulars, and we should say, it is only a special form of the question, “Are relations objective qualities of existence or are they products of the mind?” which was discussed in a former number (_The Monist_, II, 2, pp. 240-42). The idea of sameness represents the most important relation that exists; and if any relation is real, the relation of sameness must be real also. If sameness depends upon a special purpose, it appears that there can be no sameness without that purpose; and the purpose being purely mental, the sameness also would seem to be purely mental. But this is not so. Sameness is an idea, and it is no exception to other ideas. All ideas are mental symbols formed for a special purpose; but, being symbols of something, ideas are representative of some reality, or of some feature of a reality, or of some relation between two or several things. Every idea stands for something; and this quality of the significance of ideas is called their meaning or their import. The question now is, How does the idea of sameness originate in the world where, as we stated above, there is no absolute sameness, no identity? Our answer is that sameness, not identity, is a general feature of this world of reality, which impresses itself upon every mind from the very beginning of the mind’s origin. We can go farther in our statement and make it more emphatic: Mind originates and grows only on the ground of the fact that sameness is a feature of the world, and is recognised as such by feeling substance. Two points or two congruent geometrical figures being in different places are not identical. But they are of such a nature that, so far as regards the purposes of geometry, one serves the purposes in question just as well as the other, or one can be replaced by the other; and this quality is called their sameness.