Page:Principles of Political Economy Vol 1.djvu/562

540 in which they exchange for one another. On this assumption, any one of them may be taken as a representative of all the rest; since in whatever manner corn varies in value with respect to any one commodity, it varies in the same manner and degree with respect to every other; and the upward or downward movement of its value estimated in some one thing, is all that need be considered. Its money value, therefore, or price, will represent as well as anything else its general exchange value, or purchasing power; and from an obvious convenience, will often be employed by us in that representative character; with the proviso that money itself do not vary in its general purchasing power, but that the prices of all things, other than that which we happen to be considering, remain unaltered.

§ 4.The distinction between Value and Price, as we have now defined them, is so obvious, as scarcely to seem in need of any illustration. But in political economy the greatest errors arise from overlooking the most obvious truths. Simple as this distinction is, it has consequences with which a reader unacquainted with the subject would do well to begin early by making himself thoroughly familiar. The following is one of the principal. There is such a thing as a general rise of prices. All commodities may rise in their money price. But there cannot be a general rise of values. It is a contradiction in terms. A can only rise in value by exchanging for a greater quantity of B and C; in which case these must exchange for a smaller quantity of A. All things cannot rise relatively to one another. If one-half of the commodities in the market rise in exchange value, the very terms imply a fall of the other half; and reciprocally, the fall implies a rise. Things which are exchanged for one another can no more all fall, or all rise, than a dozen runners can each outrun all the rest, or a hundred trees all overtop one another. Simple as this truth is, we shall presently see that it is lost sight of in some of the most accredited doctrines