This high price of corn was not entirely due to accidental causes. Something must be attributed to the fact that the available land was insufficient for the upkeep of the population, and that new land had to be cultivated irrespective of situation or degree of fertility. The pastures which had formerly covered England were daily disappearing before the plough. It was the period of the iniquitous Enclosure Acts, when landlords set their hearts upon enclosing the common lands. Professor Cannan has drawn up an interesting chart to show the close correspondence between the progress of the enclosure movement and the high price of corn.[326] In 1813 a Commission appointed by the House of Commons to inquire into the price of corn—for the proprietors dreaded the day when the return of peace would allow of importation—came to the conclusion that new lands could not produce corn at a less cost than 80s. a quarter. What an argument for Ricardo’s theory![327] But is there no possible means of avoiding the cultivation of lands of the second and third order? Intensive cultivation might doubtless do something to swell the returns on the older lands, but only up to a certain point. It would be absurd to imagine that on a limited area of land an unlimited quantity of subsistence can be produced. There must be a limit somewhere—an elastic limit perhaps, and one which the progress of science will push farther and farther away, even beyond our wildest hopes. But the cultivator stops long before this ideal limit is reached, for practice has taught him that the game is not worth the candle, because the outlay of capital and labour exceeds the profits on the return. This practical limit is determined for him by the law of diminishing returns.[328] That law is indispensable to an understanding of the Ricardian theory, and is implied in Malthus’s theory of population. Its discovery is still earlier, and we have an admirable statement of it in Turgot’s writings: “It can never be imagined that a doubling of expenditure would result in doubling the product.” Malthus, unconsciously no doubt, repeated Turgot’s dictum.[329] It is evident, says he, that as cultivation extends, the annual addition made to the average product must continually diminish.[330] Ricardo witnessed the operation of the law under his very eyes, and he frequently hinted at the decreasing returns yielded by capital successively applied to the same land. Even in cases of that kind, where recourse to new lands was impossible, rents were bound to increase.