But with regard to capital actually sunk in improvements, and not requiring periodical renewal, but spent once for all in giving the land a permanent increase of productiveness, it appears to me that the return made to such capital loses altogether the character of profits, and is governed by the principles of rent. It is true that a landlord will not expend capital in improving his estate unless he expects from the improvement an increase of income surpassing the interest of his outlay. Prospectively, this increase of income may be regarded as profit; but, when the expense has been incurred and the improvement made, the rent of the improved land is governed by the same rules as that of the unimproved. Mr. Carey (as well as Bastiat) has declared that there is a law of increasing returns from land. He points out that everything now existing could be reproduced to-day at a less cost than that involved in its original production, owing to our advance in skill, knowledge, and all the arts of production; that, for example, it costs less to make an axe now than it did five hundred years ago; so also with a farm, since a farm of a given amount of productiveness can be brought into cultivation at less cost to-day than that originally spent upon it. The gain of society has, we all admit, been such that we produce almost everything at a less cost now than long ago; but to class a farm and an axe together overlooks, in the most remarkable way, the fact that land can not be created by labor and capital, while axes can, and that too indefinitely. Nor can the _produce_ from the land be increased indefinitely at a diminishing cost. This is sometimes denied by the appeal to facts: “It can be abundantly proved that, if we take any two periods sufficiently distant to afford a fair test, whether fifty or one hundred or five hundred years, the production of the land relatively to the labor employed upon it has progressively become greater and greater.”(182) But this does not prove that an existing tendency to diminishing returns has not been more than offset by the progress of the arts and improvements. “The advance of a ship against wind and tide is [no] proof that there is no wind and tide.” In a work entitled “The Past, the Present, and the Future,” Mr. Carey takes [a] ground of objection to the Ricardo theory of rent, namely, that in point of historical fact the lands first brought under cultivation are not the most fertile, but the barren lands. “We find the settler invariably occupying the high and thin lands requiring little clearing and no drainage. With the growth of population and wealth, other soils yielding a larger return to labor are always brought into activity, with a constantly increasing return to the labor expended upon them.”