Looking at the three causes together, we see that the first and last relate to the statics, and the second to the dynamics of the subject. We need to remember that Malthus is having regard in the first instance not to the value but to the quantity of the produce. Now, apart from questions of value, it is possible there might be, in a country, land yielding to the sower more than he sowed; but it might be an ordinary excess, secured by all producers in that country, for the land might be all equally fertile, and production from land might be the most fertile of industries. In that case, even if the land was a State monopoly and the producer’s gains could be taken from him by a tax, there would be nothing corresponding to rent, in the received sense. But, as soon as there were differences in the fertility, and therefore differences in the quantity produced at the same cost, the farmer who had the difference on his side could be said to have a rent. It is this surplus, conjoined with the institution of private property, that, according to Malthus, makes leisure and mental progress, and even great material prosperity, possible.[532] The rent is properly the extra profits, and not the equivalent paid over for them to a landlord; rent can easily exist without a landlord. “It may be laid down, therefore, as an incontrovertible truth, that, as a nation reaches any considerable degree of wealth, and any considerable fulness of population, which of course cannot take place without a great fall both in the profits of stock and the wages of labour, the separation of rents, as a kind of fixture upon lands of a certain quality, is a law as invariable as the action of the principle of gravity. And that rents are neither a mere nominal value, nor a value unnecessarily and injuriously transferred from one set of people to another, but a most real and essential part of the whole value of the national property, and placed by the laws of nature where they are, on the land, by whomsoever possessed, whether the landlord, the crown, or the actual cultivator.”[533] It is the second cause that brings the first and third into operation in such a way as to produce the rents that we actually know in an old country. The fertility which secures a produce beyond cost makes extra profits possible; the growing population, which gives the produce a value, makes them actual; and the gradations in fertility, whereby a uniform increase in the value of produce creates far from uniform extra profits to different cultivators, give the extra profits the peculiar graduated character, which is characteristic of rent in the economical sense of the word.