Chapter I. Of Value.

(if they have any) constitutes a minimum below which they can not permanently fall; and the large class, which can be multiplied ad libitum by labor and capital, and of which the cost of production fixes the maximum as well as the minimum at which they can permanently exchange [if there be free competition]. But there is still a third kind of commodities to be considered—those which have, not one, but several costs of production; which can always be increased in quantity by labor and capital, but not by the same amount of labor and capital; of which so much may be produced at a given cost, but a further quantity not without a greater cost. These commodities form an intermediate class, partaking of the character of both the others. The principal of them is agricultural produce. We have already made abundant reference to the fundamental truth that in agriculture, the state of the art being given, doubling the labor does not double the produce; that,