There is no doubt that “Value” is generally used, in ordinary language and thought, in both these senses. But there is also no doubt that powers or values of the latter sort _in general_ do not enter into economic study at all. We have nothing to do with the heating value of coal, or the resisting power of iron, or the fattening properties of oil-cake; these are purely physical or technical matters. But, inside this class of Objective Values, there is one species which has a peculiarly economic interest, and that is, the “power of exchange” or “purchasing power.” By this is meant the capacity or power of a good to obtain other goods in exchange. Of course, the word “power” here is also misleading. No good has this power in itself. It is, at best, a power conferred on goods by the complex machinery of an organised economic community, and it does not exist outside of a system of exchange. It is a power that lies in the connection or relation of two things, and not in either of the things. Jevons very well called it a Ratio of Exchange. But it is purely an “objective” relation as we have defined it; as objective, for instance, as heating power. When the quarter of wheat in the market exchanges for 25s., we say, indifferently, that the “exchange value of the wheat is 25s.,” or that “the purchasing power is 25s.,” or that “the ratio of exchange between the wheat and the shillings is as 25 to 1.” It has been the ambition of economists to explain all kinds of value from a single universal conception, but so far the result has only been to group heterogeneous elements under a common name. It might be possible, perhaps, to connect them all under the general conception of “that which avails,” or under the relation of Means to End; but whether much is gained by this for economic science is doubtful.[4] [4] Böhm-Bawerk, like Neumann, while acknowledging that the two conceptions have many internal and external relations, and that both spring undoubtedly from one common root, thinks that any more universal conception, which should embrace them both, would be _ganz leer und schattenhaft_. Here, at any rate, we shall follow the line which has led to good results among the Austrian economists, and consider Subjective and Objective Value in general as two independent conceptions accidentally associated in common usage.