Perhaps it may conduce to a fuller understanding of the law of rent to put it in this form: The ownership of a natural agent of production will give the power of appropriating so much of the wealth produced by the exertion of labor and capital upon it as exceeds the return which the same application of labor and capital could secure in the least productive occupation in which they freely engage. This, however, amounts to precisely the same thing, for there is no occupation in which labor and capital can engage which does not require the use of land; and, furthermore, the cultivation or other use of land will always be carried to as low a point of remuneration, all things considered, as is freely accepted in any other pursuit. Suppose, for instance, a community in which part of the labor and capital is devoted to agriculture and part to manufactures. The poorest land cultivated yields an average return which we will call 20, and 20 therefore will be the average return to labor and capital, as well in manufactures as in agriculture. Suppose that from some permanent cause the return in manufactures is now reduced to 15. Clearly, the labor and capital engaged in manufactures will turn to agriculture; and the process will not stop until, either by the extension of cultivation to inferior lands or to inferior points on the same land, or by an increase in the relative value of manufactured products, owing to the diminution of production—or, as a matter of fact, by both processes—the yield to labor and capital in both pursuits has, all things considered, been brought again to the same level, so that whatever be the final point of productiveness at which manufactures are still carried on, whether it be 18 or 17 or 16, cultivation will also be extended to that point. And, thus, to say that rent will be the excess in productiveness over the yield at the margin, or lowest point, of cultivation, is the same thing as to say that it will be the excess of produce over what the same amount of labor and capital obtains in the least remunerative occupation. The law of rent is, in fact, but a deduction from the law of competition, and amounts simply to the assertion that as wages and interest tend to a common level, all that part of the general production of wealth which exceeds what the labor and capital employed could have secured for themselves, if applied to the poorest natural agent in use, will go to land owners in the shape of rent. It rests, in the last analysis, upon the fundamental principle, which is to political economy what the attraction of gravitation is to physics—that men will seek to gratify their desires with the least exertion.