The Wealth of Nations by Part 4 Chapter 5 Page 79

they must generally be able to judge better of it than the legislator can do. The law, however, which obliged the farmer to exercise the trade of a corn merchant was by far the most pernicious of the two.

It obstructed not only that division in the employment of stock which is so advantageous to every society, but it obstructed likewise the improvement and cultivation of the land. By obliging the farmer to carry on two trades instead of one, it forced him to divide his capital into two parts, of which one only could be employed in cultivation. But if he had been at liberty to sell his whole crop to a corn merchant as fast as he could thresh it out, his whole capital might have returned immediately to the land, and have been employed in buying more cattle, and hiring more servants, in order to improve and cultivate it better.