1. Money is an instrument whose purpose is to be accepted in exchange for a commodity and, more generally, in payment.
The use value of current currencies is reduced to the fact that they have an exchange value and, more broadly, a liberating power. Many transfers of purchasing power are made, and often can only be made, in monetary terms.
2. The utilities of commodities are not reduced to the fact that they have an exchange value.
The usefulness of current currencies is reduced to the fact that they have a discharging value and that they can be exchanged for other currencies that are current.
3. The usefulness of a currency that is current lies in the fact that it is not a commodity.
A wad of banknotes can be transformed into a commodity if it is put under glass and in a frame these notes, and then the object thus made is sold. If this work finds a buyer at the asking price and if this price is paid in money, then the latter is used as an instrument, which is not a commodity since its utility, or use value, lies entirely in its exchange value.
4. Banknotes, coins and other payment instruments that are no longer in circulation become commodities when they are offered for sale to collectors.
A conception of economics that admits that currencies in circulation are commodities like any other, or almost like any other, is based on the incomplete transformation of the notion of commodity into a concept properly so-called.
5. In the Economic Vocabulary cited in argument of the previous proposition, there is no entry "Commodity".
In the index of each of the two volumes of Raymond Barre's Political Economy, there is also no entry for the word "Commodity". In the Economic and Financial Dictionary published by Le Seuil, the same is true33. Etc., etc., etc. It is to be believed, against all evidence, that economic exchanges do not have as their own terms either one commodity and a quantity of money, or two commodities in the case of barter. It is also to be believed that there is no logical necessity in using in economic science, in the same sense, the expressions "commodity exchange", "commodity exchange", "economic exchange", without which a true definition33of the object of this science is inarticulable.