resulting from the exertions of each group of producers is the source from which wages and profits are drawn. The aggregate wages and profits in each industry will vary with the value of the aggregate products. But this total value depends upon what it will exchange for of the products of other groups; that is, this value depends on the reciprocal demand of one group for the commodities of the other groups, as compared with the demand of the other groups for its products. For example, although cost of production is low in group A, if the demand from outside groups were to be strong, the exchange value of A's products would rise, and A would get more of other goods in exchange; that is, the total produce is large, but a second increment, arising from a higher exchange value, is to be shared among A's laborers and capitalists. A few years ago, about 1878-1879, the value of wheat in the United States rose because of the increased demand from Europe, where the harvests had been unusually deficient. There had been no falling off in the productiveness of the farming industry of the United States to cause the increased price; but the relative demand of other industrial groups for wheat, the product of the farming industry, raised the exchange value of wheat, and so increased the industrial rewards of those engaged as laborers and capitalists in farming. So [pg 271] it is to be concluded that since there is no free movement of labor and capital between non-competing groups, wages and profits may constantly remain at rates which are not in correspondence with the actual sacrifice, or cost, to labor and capital in different groups; hence, their products do not exchange for each other in proportion to their costs of production. Reciprocal demand is the law of their value.
It will be said, at once, that the foregoing conception of cost of production is entirely opposed to the language of practical men of