The Wealth of Nations by Part 4 Chapter 5 Page 33

proportion which its average money price bears to the average money price of corn. The real value of corn does not vary with those variations in its average money price, which sometimes occur from one century to another. It is the real value of silver which varies with them.

Bounties upon the exportation of any homemade commodity are liable, first to that general objection which may be made to all the different expedients of the mercantile system; the objection of forcing some part of the industry of the country into a channel less advantageous than that in which it would run of its own accord: and, secondly, to the particular objection of forcing it, not only into a channel that is less advantageous, but into one that is actually disadvantageous; the trade which cannot be carried on but by means of a bounty being necessarily a losing trade.