Commodities as More or Less Salable

[On the Origins of Money (1892)]

It is an error in economics, as prevalent as it is patent, that all commodities, at a definite point of time and in a given market, may be assumed to stand to each other in a definite relation of exchange, in other words, may be mutually exchanged in definite quantities at will. It is not true that in any given market 10 cwt. of one article = 2 cwt. of another = 3 lbs. of a third article, and so on.