Agricultural products of equal quantity and quality are produced on pieces of land of unequal fertility, even when the same amount of skill is displayed by the husbandman, with very different outlays of capital and labor.[150-1] And yet the price of these products in the same market is uniformly the same. This price must, on the supposition of free and intelligent competition, be, in the long run, at least high enough to cover the cost of production on even the worst soil (the margin of cultivation according to Fawcett), which must be brought under cultivation in order to satisfy the aggregate want. (See § 110.) This worst land need yield no rent.[150-2] The better land which, with an equal outlay of labor and capital, produces a greater yield, furnishes an excess over the cost of production.[150-3] This excess is rent, which, as a rule, is obviously higher in proportion as the difference in fertility between the worst and the better land is greater. The person who cultivates the land of a stranger may unhesitatingly turn this rent over to the owner; since, notwithstanding his so doing, all that he has himself contributed to production in labor and capital of his own, returns to him entire in the product.[150-4] According to § 34, a continual increase in the amount of labor and capital lavished on the fertilization of land, agricultural science remaining the same, leads, sooner or later to this, that every new addition of capital or labor becomes relatively less remunerative than the preceding.[150-5] The worse the land is, the sooner is this point reached. Hence, it necessarily happens that, with an increase in the aggregate want of agricultural products, greater and greater amounts of labor and capital are employed in the further fertilization of land, and that there comes to be a greater difference between the fertility of the worst and better lands, in consequence of which the rent of the latter rises.[150-6]