Page:Sir William Petty - A Study in English Economic Literature - 1894.djvu/59

60 important consideration in political œconomies"(344). This equation will be an expression of value. Labor not only creates value but it is the measure of value. He uses the following illustration: "Let a hundred men work ten years upon corn, and the same number of men the same time upon silver; I say, that the neat proceed of the silver is the price of the whole neat proceed of the corn" (30). The natural rent of land is the proceed of the harvest minus the food and necessaries of the laborer. The value of this in money is the amount of money a man can save in the same time over and above his expenses while mining silver during the same period of time.

In a later work, the "Anatomy of Ireland," he makes another attempt at expressing the value of natural rent. With the one I have already given he is discontented, because in it he has introduced the factor "labor," which should have been kept out. This difficulty he avoids in a curious way. Natural rent is expressed in the terms of the commodities raised upon the land—butter, cheese, corn and wool—whatever they may be. For accuracy, he makes the following supposition: "Suppose two acres of pasture land inclosed, and put thereunto a weaned calf." Suppose this animal to become one hundred pounds heavier. A hundred-weight of such flesh he supposes to be fifty days' food. This amount and the interest on the value of the calf is the value, or year's rent of the land. If a man's labor can make the said land yield sixty days' food, then that overplus is the value of the man's labor or wages, both being expressed by