When a nation binds itself by treaty, either to permit the entry of certain goods from one foreign country which it prohibits from all others, or to exempt the goods of one country from duties to which it subjects those of all others, the country, or at least the merchants and manufacturers of the country, whose commerce is so favoured, must necessarily derive great advantage from the treaty. Those merchants and manufacturers enjoy a sort of monopoly in the country which is so indulgent to them. That country becomes a market, both more extensive and more advantageous for their goods: more extensive, because the goods of other nations being either excluded or subjected to heavier duties, it takes off a greater quantity of theirs; more advantageous, because the merchants of the favoured country, enjoying a sort of monopoly there, will often sell their goods for a better price than if exposed to the free competition of all other nations.
Such treaties, however, though they may be advantageous to the merchants and manufacturers of the favoured, are necessarily disadvantageous to those of the favouring country. A monopoly is thus granted against them to a foreign nation; and they must frequently buy the foreign goods they have occasion for, dearer than if the free competition of other nations was admitted. That part of its own produce with which such a nation purchases foreign goods, must consequently be sold cheaper; because, when two things are exchanged for one another, the cheapness of the one is a necessary consequence, or rather is the same thing, with the dearness of the other. The exchangeable value of its annual produce, therefore, is likely to be diminished by every such treaty. This diminution, however, can scarce amount to any positive loss, but