The Wealth of Nations by Part 4 Chapter 8 Page 36

To hurt in any degree the interest of any one order of citizens, for no other purpose but to promote that of some other, is evidently contrary to that justice and equality of treatment which the sovereign owes to all the different orders of his subjects. But the prohibition certainly hurts, in some degree, the interest of the growers of wool, for no other purpose but to promote that of the manufacturers.

Every different order of citizens is bound to contribute to the support of the sovereign or commonwealth. A tax of five, or even of ten shillings upon the exportation of every ton of wool would produce a very considerable revenue to the sovereign.

It would hurt the interest of the growers somewhat less than the prohibition, because it would not probably lower the price of wool quite so