The Wealth of Nations by Part 4 Chapter 3 Page 53

France would in this case carry on a direct foreign trade of consumption with England; whereas England would carry on a round-about trade of the same kind with France. The different effects of a capital employed in the direct and of one employed in the round-about foreign trade of consumption have already been fully explained.

There is not, probably, between any two countries a trade which consists altogether in the exchange either of native commodities on both sides, or of native commodities on one side and of foreign goods on the other. Almost all countries exchange with one another partly native and partly foreign goods.

That country, however, in whose cargoes there is the greatest proportion of native, and the least of foreign goods, will always be the principal gainer.