The Wealth of Nations by Part 5 Chapter 2 Page 60

therefore, be in a great measure arbitrary.

Taxes which are proportioned, not to the Rent, but to the Produce of Land

Taxes upon the produce of land are in reality taxes upon the rent; and though they may be originally advanced by the farmer, are finally paid by the landlord.

When a certain portion of the produce is to be paid away for a tax, the farmer computes, as well as he can, what the value of this portion is, one year with another, likely to amount to, and he makes a proportionable abatement in the rent which he agrees to pay to the landlord. There is no farmer who does not compute beforehand what the church tithe, which is a land-tax of this kind, is, one year with another, likely to amount to.