The Wealth of Nations by Part 5 Chapter 2 Page 156

than enough. The emoluments of offices, therefore, can in most cases very well bear to be taxed. The persons, besides, who enjoy public offices, especially the more lucrative, are in all countries the objects of general envy, and a tax upon their emoluments, even though it should be somewhat higher than upon any other sort of revenue, is always a very popular tax.

In England, for example, when by the land-tax every other sort of revenue was supposed to be assessed at four shillings in the pound, it was very popular to lay a real tax of five shillings and sixpence in the pound upon the salaries of offices which exceeded a hundred pounds a year, the pensions of the younger branches of the royal family, the pay of the officers of the army and navy, and a few others less obnoxious to envy excepted. There are in England no