The purchasing power of a twenty-dollar piece does not reside in the holder.[212] It goes without saying that this power can exist in an article only when there is another thing for which it can be exchanged and when there are men to effect the exchanging. It is not implied that articles of commerce have the power to exchange themselves in market places without human intervention. But the purchasing power resides in the article; it is always referred to the article in our thought, and it leads to nonsensical results to run counter to our commonest and most practical forms of thought and endeavor to locate it elsewhere. The end of the theory of value is to explain the causes which govern exchange values, or practically, market prices. Other conceptions of value than exchange value derive their just importance in political economy only from the aid they may render in this explanation. This defines the place of the conception of esteem value. A finished explanation of exchange values is impossible without a theory of esteem values, just as an ultimate explanation of the counterbalancing powers of different objects in the scales is vain without the general law of gravitation. The power of an apple to counterbalance two eggs might have been thought of as a matter purely relative between apples and eggs, before the general conception was framed of the common attraction exerted by the earth upon both apples and eggs. Exchange values were once stated to be “purely relative.” The objectionable point in the statement lies in the adverb “purely.” For exchange values are derived from esteem values very much as weights, or powers to counterbalance, are derived from the earth’s attraction. That is, these two derivations are generally similar. Here as elsewhere analogies can be pressed too far. The derivation of the exchange values of different goods in the social market from the esteem values put upon these goods by the consumers, or purchasers in the society, is a process indefinitely more difficult to explain than the relative weights of ponderables.[213] Given the gravity of separate objects it is but a step to explain their relative weights, but given the esteem values of different economic commodities it is a long road to follow the process through which these determine the exchange values of the same commodities. If esteem value be the gravity behind exchange value, the case is rendered complex in that each good possesses a separate esteem value for every different consumer whereas there is but one earth to attract each object whose relative weight we desire to explain.