The Wealth of Nations by Part 4 Chapter 4 Page 12

that duty should be drawn back upon the exportation to the colonies of any commodities, of the growth or manufacture either of Europe or the East Indies, except wines, white calicoes, and muslins.

Drawbacks were, perhaps, originally granted for the encouragement of the carrying trade, which, as the freight of the ships is frequently paid by foreigners in money, was supposed to be peculiarly fitted for bringing gold and silver into the country. But though the carrying trade certainly deserves no peculiar encouragement, though the motive of the institution was perhaps abundantly foolish, the institution itself seems reasonable enough. Such drawbacks cannot force into this trade a greater share of the capital of the country than what would have gone to it of its own accord had there been no duties upon importation.