In this popular sense, therefore, labour, like commodities, may be said to have a real and a nominal price. Its real price may be said to consist in the quantity of the necessaries and conveniencies of life which are given for it; its nominal price, in the quantity of money. The labourer is rich or poor, is well or ill rewarded, 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 silver which are contained at different times in coin of the same denomination; and, secondly, to those which arise from the different values of equal quantities of gold and silver at different times.
Princes and sovereign states have frequently fancied that they had a temporary interest to diminish the quantity of pure metal contained in their coins; but they seldom have fancied that they had any to augment it. The quantity of metal contained in the coins, I believe of all nations, has, accordingly, been almost continually diminishing, and hardly ever augmenting. Such variations therefore tend almost always to diminish the value of a money rent.