Introduction One of the distinctive statements of Marchands, salariat et capitalistes (hereafter MSC) is that, in the analysis of a monetary economy, the unit of account is the starting point, as the catalog of commodities is the starting point of the standard analysis of a market economy (value theory). This statement has three corollaries: a) the unit of account is purely nominal; b) it is arbitrary: it is proclaimed by a public institution outside the market, and this proclamation is the necessary and sufficient condition to have it adopted by monetary subjects (agents); c) the means of payment is a concept that comes logically after the unit of account: its introduction answers the question, not of the unit in which one counts, but of how much is counted.