enable rent, in the progress of society, to rise gradually to a much higher limit than it could otherwise attain, since they enable a much lower quality of land to be ultimately cultivated. But in the case we are now supposing, which nearly corresponds to the usual course of things, this ultimate effect becomes the immediate effect. Suppose cultivation to have reached, or almost reached, the utmost limit permitted by the state of the industrial arts, and rent, therefore, to have attained nearly the highest point to which it can be carried by the progress of population and capital, with the existing amount of skill and knowledge. If a great agricultural improvement were suddenly introduced, it might throwback rent for a considerable space, leaving it to regain its lost ground by the progress of population and capital, and afterwards to go on further. But, taking place, as such improvement always does, very gradually, it causes no retrograde movement of either rent or cultivation; it merely enables the one to go on rising, and the other extending, long after they must otherwise have stopped. It would do this even without the, necessity of resorting to a worse quality of land; simply by enabling the lands already in cultivation to yield a greater produce, with no increase of the proportional cost. If by improvements of agriculture all the lands in cultivation could be made, even with double labour and capital, to yield a double .produce, (supposing that in the meantime population increased so as to require this double quantity) all rents would be doubled.
To illustrate the point, let us revert to the numerical example in a former page. Three qualities of land yield respectively 100, 80, and 60 bushels to the same outlay on the same extent of surface. If No. 1 could be made to yield 200, No. 2, 160, and No. 3, 120 bushels, at only double the expense, and therefore without any increase of the cost of production, and if the population, having doubled, required all this increased quantity, the rent of No. I would be 80 bushels instead of 40, and of No. 2, 40 instead of 20, while the price and value per bushel would be the same as before:
