and that would convey no precise idea, at least until he added a good many explanations, which would be very inconvenient. Men have, therefore, been obliged to choose by preference, for their scale of comparison, commodities[1] which, being more commonly in use and hence of a better known value, were more like one another, so that in consequence their value had more relation to the number or the quantity than to the quality.
S36
The want of an exact correspondence between the value and the number or quantity has been made up for by a mean valuation,[2] which becomes a sort of ideal money.
In a country where there is only one race of sheep, the value of a fleece or of a sheep may easily be taken for the common measure of values, and we may say that a barrel of wine or a piece of stuff is worth a certain number of fleeces or of sheep. In reality, there is some inequality among sheep; but when it is a question of actually selling sheep, care is taken to make allowance for this inequality, and to reckon, for example, two lambs as one sheep. When it is a question of valuing any other commodity, people take as their unit[3] the common value of a sheep of medium age and of medium condition. In this way the expression of values in terms of sheep becomes, as it were, a conventional language, and this word, one sheep, simply signifies in the language of commerce a certain value; carrying to the mind of those who hear it not merely the
