1,500l., a year, his profits would be so diminished that he would not be able to obtain the same return for his capital as if it were invested in some other business. He would virtually lose by farming because he could make more of his money if otherwise invested; and no class of traders will continue a business when it becomes comparatively unremunerative. The landlord would therefore be powerless to obtain from A a rent much exceeding 1,000l. But there is a further question: What would prevent the farmer from paying a less rent than 1,000l., say a rent of 700l.? This would certainly be prevented by the competition of others anxious to engage in farming operations. Those who had a practical knowledge of farming would be able to calculate with considerable exactness what would be the net produce on A's farm, and they would thus know, if A was only paying a rent of 700l. a year, that he was paying 300l. a year less than might be paid, with a realisation of a fair profit to the farmer. Others would come forward and offer a higher rent for the farm, and A would consequently be obliged to leave the farm or else pay a higher rent.
It is, therefore, no exaggeration to say that, when land is freely competed for, rents are approximately adjusted according to Ricardo's theory. We say "approximately," because there is a certain margin of variation for which allowance ought always to be made. Thus, two land-agents may differently value the net produce of a farm. A landlord, rather than lose an old tenant, may often continue to receive less rent from him than a new tenant would be willing to pay; but in such a case competition is to a certain extent interfered with by the feelings which arise from affection and old association. Ricardo's theory is strictly true upon the supposition that there is free competition, and in practical life the results which may be deduced from the theory really occur in proportion to the extent to which competition acts without interference from other disturbing agencies. Illustration from astronomy.It is no uncommon thing to say that the sun causes the earth to revolve in an ellipse, and yet the earth never does so move, it oscillates from one side to the other of this ellipse in consequence of the disturbing