The Wealth of Nations by Part 5 Chapter 2 Page 61

The tithe, and every other land-tax of this kind, under the appearance of perfect equality, are very unequal taxes; a certain portion of the produce being, in different situations, equivalent to a very different portion of the rent. In some very rich lands the produce is so great that the one half of it is fully sufficient to replace to the farmer his capital employed in cultivation, together with the ordinary profits of farming stock in the neighbourhood.

The other half, or, what comes to the same thing, the value of the other half, he could afford to pay as rent to the landlord, if there was no tithe. But if a tenth of the produce is taken from him in the way of tithe, he must require an abatement of the fifth part of his rent, otherwise he cannot get back his capital with the ordinary profit. In this case the rent of