But if the agricultural improvement, or the barrow and the water-barrel, have only a limited duration, which we can appreciate approximately, a sinking fund must be added to the interest, in order that, when these portions of capital are worn out, the proprietor may be enabled to renew them. Still it is the law of justice which governs the transaction. We must not suppose, however, that the franc with which each hectolitre is burdened as interest is an invariable quantity. It represents a value, and is subject to the law of values. It rises or falls with the variation of supply and demand,—that is to say, according to the exigencies of the times and the interests of society. It is generally thought that this species of remuneration has a tendency to rise, if not in the case of manufacturing, at least in the case of agricultural improvements. Supposing this rent to have been equitable at the beginning, it has a tendency, it is said, to degenerate into abuse; because the proprietor, sitting with his hands across, sees it increase year after year, solely in consequence of the increase of population and the enlarged demand for corn. I allow that this tendency exists, but it is not peculiar to the rent of land,—it is common to all departments of industry. In all, value increases with the density of population, and even the common day-labourer earns more in Paris than he could in Brittany. And then, as regards the rent of land, the tendency to which we have referred is powerfully counterbalanced by another tendency—that of progress. An amelioration, realized at the present day by improved processes, effected with less manual labour, and at a time when the rate of interest has fallen, saves our paying too dearly for improvements effected in former times. The fixed capital of the landed proprietor, like that of the manufacturer, is deteriorated in the long-run by the invention of instruments of equal value and greater efficiency. This is a magnificent Law, which overturns the melancholy theory of Ricardo; and it will be explained more in detail when we come to the subject of landed property. Observe, that the problem of the distribution of the services which form the remuneration of permanent improvements can be resolved only by a reference to the law of ‹interest›. The capital [p207] itself cannot be spread over a succession of purchasers, for this is rendered impossible by their indeterminate number. The first would pay for the last, which would be unjust. Besides, a time would arrive when the proprietor would become possessed both of the capital laid out in the improvement, and of the improvement itself, which would be equally unfair. Let us acknowledge, then, that the natural mechanism of society is too ingenious to require the substitution of artificial contrivances. I have presented the phenomenon in its simplest form, in order to render it intelligible; but, in practice, things do not take place quite as I have described them.