on the point which cultivation has reached in its downward progress—in its encroachments on the barren lands, and its gradually increased strain upon the powers of the more fertile. Now, the force which urges cultivation in this downward course is the increase of people; while the counter-force, which checks the descent, is the improvement of agricultural science and practice, enabling the same soil to yield to the same labor more ample returns. The costliness of the most costly part of the produce of cultivation is an exact expression of the state, at any given moment, of the race which population [pg 468] and agricultural skill are always running against each other.
§ 2. In the law of Rent.
The degree of productiveness of this extreme margin is an index to the existing state of the distribution of the produce among the three classes, of laborers, capitalists, and landlords. When the demand of an increasing population for more food can not be satisfied without extending cultivation to less fertile land, or incurring additional outlay, with a less proportional return, on land already in cultivation, it is a necessary condition of this increase of agricultural produce that the value and price of that produce must first rise. The price of food will always on the average be such that the worst land, and the least productive installment of the capital employed on the better lands, shall just replace the expenses with the ordinary profit. If the least favored land and capital just do thus much, all other land and capital will yield an extra profit, equal to the proceeds of the extra produce due to their superior productiveness; and this extra profit becomes, by competition, the prize of the landlords. Exchange [pg 469] and money, therefore, make no difference in the law of rent: it is the same as we originally293 found it. Rent is the extra return made to agricultural capital when employed with peculiar advantages; the exact equivalent of what those advantages enable the producers to economize in the