The Wealth of Nations by Part 4 Chapter 5 Page 6

But the very reason for which it has been thought necessary to grant a bounty is the supposed insufficiency of the price to do this.

The average price of corn, it has been said, has fallen considerably since the establishment of the bounty. That the average price of corn began to fall somewhat towards the end of the last century, and has continued to do so during the course of the sixty-four first years of the present, I have already endeavoured to show. But this event, supposing it to be as real as I believe it to be, must have happened in spite of the bounty, and cannot possibly have happened in consequence of it. It has happened in France, as well as in England, though in France there was not only no bounty, but, till 1764, the exportation of corn was subjected to a general prohibition.