The extent of the home trade, and of the capital which can be employed in it, is necessarily limited by the value of the surplus produce of all those distant places within the country which have occasion to exchange their respective productions with one another; that of the foreign trade of consumption, by the value of the surplus produce of the whole country, and of what can be purchased with it; that of the carrying trade, by the value of the surplus produce of all the different countries in the world. Its possible extent, therefore, is in a manner infinite in comparison of that of the other two, and is capable of absorbing the greatest capitals.
The consideration of his own private profit is the sole motive which determines the owner of any capital to employ it either in agriculture, in manufactures, or in some particular branch of the wholesale or retail trade. The different quantities of productive labour which it may put into motion, and the different values which it may add to the annual produce of the land and labour of the society, according as it is employed in one or other of those different ways, never enter into his thoughts. In countries, therefore, where agriculture is the most profitable of all employments, and farming and improving the most direct roads to a splendid fortune, the capitals of individuals will naturally be employed in the manner most advantageous to the whole society. The profits of agriculture, however, seem to have no superiority over those of other employments in any part of Europe. Projectors, indeed, in every corner of it, have, within these few years, amused the public with most magnificent accounts of the profits to be made by the cultivation and improvement of land. Without entering into any particular discussion of their calculations, a very simple observation may satisfy us that the result of them must be false. We see, every day, the most splendid fortunes, that have been acquired in the course of a single life, by trade and manufactures, frequently from a very small capital, sometimes from no capital. A single instance of such a fortune, acquired by agriculture in the same time, and from such a capital, has not, perhaps, occurred in Europe, during the course of the present century. In all the great