But while the increase of population thus increases rent by lowering the margin of cultivation, it is a mistake to look upon this as the only mode by which rent advances as population grows. Increasing population increases rent, without reducing the margin of cultivation; and notwithstanding the dicta of such writers as McCulloch, who assert that rent would not arise were there an unbounded extent of equally good land, increases it without reference to the natural qualities of land, for the increased powers of co-operation and exchange which come with increased population are equivalent to—nay, I think we can say without metaphor, that they give—an increased capacity to land. I do not mean to say merely that, like an improvement in the methods or tools of production, the increased power which comes with increased population gives to the same labor an increased result, which is equivalent to an increase in the natural powers of land; but that it brings out a superior power in labor, which is localized on land—which attaches not to labor generally, but only to labor exerted on particular land; and which thus inheres in the land as much as any qualities of soil, climate, mineral deposit, or natural situation, and passes, as they do, with the possession of the land. An improvement in the method of cultivation which, with the same outlay, will give two crops a year in place of one, or an improvement in tools and machinery which will double the result of labor, will manifestly, on a particular piece of ground, have the same effect on the produce as a doubling of the fertility of the land. But the difference is in this respect—the improvement in method or in tools can be utilized on any land; but the improvement in fertility can be utilized only on the particular land to which it applies. Now, in large part, the increased productiveness of labor which arises from increased population can be utilized only on particular land, and on particular land in greatly varying degrees.