According to this liberal and generous system, therefore, the most advantageous method in which a landed nation can raise up artificers, manufacturers and merchants of its own, is to grant the most perfect freedom of trade to the artificers, manufacturers and merchants of all other nations. It thereby raises the value of the surplus produce of its own land, of which the continual increase gradually establishes a fund, which in due time necessarily raises up all the artificers, manufacturers and merchants whom it has occasion for.
When a landed nation, on the contrary, oppresses either by high duties or by prohibitions the trade of foreign nations, it necessarily hurts its own interest in two different ways. First, by raising the price of all foreign goods and of all sorts of manufactures, it necessarily sinks the real value of the surplus produce of its own land, with which, or, what comes to the same thing, with the price of which, it purchases those foreign goods and manufactures. Secondly, by giving a sort of monopoly of the home market to its own merchants, artificers and manufacturers, it raises the rate of mercantile and manufacturing profit in proportion to that of agricultural profit, and consequently either draws from agriculture a part of the capital which had before been employed in it, or hinders from going to it a part of what would otherwise have gone to it. This policy, therefore, discourages agriculture in two different ways; first, by sinking the real value of its produce, and thereby lowering the rate of its profit; and, secondly, by raising the rate of profit in all other employments. Agriculture is rendered less advantageous, and trade and manufactures more advantageous than they otherwise would be; and every man is tempted by his own interest to turn, as much as he can, both his capital and his industry from the former to the latter employments.