in proportion to the real, not to the nominal price of his labour.

The distinction between the real and the nominal price of commodities and labour is not a matter of mere speculation, but may sometimes be of considerable use in practice. The same real price is always of the same value; but on account of the variations in the value of gold and silver, the same nominal price is sometimes of very different values. When a landed estate, therefore, is sold with a reservation of a perpetual rent, if it is intended that this rent should always be of the same value, it is of importance to the family in whose favour it is reserved that it should not consist in a particular sum of money. Its value would in this case be liable to variations of two different kinds; first, to those which arise from the different quantities of gold and