The purpose of the paper is to offer a logical genesis of the differenciation of agents in two classes: capitalist entrepreneurs and wage-earners. The model presented here does not follow the Classical (or Marxian) tradition (where the two opposed classes are the straight consequence of the concentration of the means of production in the hands of a limited fraction of people). It does not follow mainstream economists either (no difference according to general competitive equilibrium or a difference taken as given in labour economics in general). Models belonging to those traditions fail to reproduce a major stylised fact: wage-earners cannot be distinguished from entrepreneurs when they are in the market for commodities but they radically differ in the 'market for labour' or in production (wage-earners do not produce for their own account but for that of entrepreneurs who get pro…ts, not wages). Modern tentatives to deal with the differenciation of agents (Matsuyama for instance) explain it by a progrssive differenciation of the level of wealth up to a threshold which makes some agents able to accumulate and others not. We propose a different view based on the process of issuance of money. If a fraction of agents have not a direct access to that process they cannot act in the market for their own account. The alternatives they have are limited to autarky or to work for the account of those who have additional alternatives due to their direct access to money (to be independent producers or entrepreneurs hiring wage-earners). The model makes explicit the necessary and sufficient conditions for the existence of an E-equilibrium in which co-exist heterogeneous agents (entrepreneurs and wage-earners) starting from a population homogeneous except for bank rationing. These reasonable conditions are: an efficient monetary system, a sufficient gap between productivity of production in mass compared to other types and a possibility to induce wage-earners to work signi…ficantly more than they would as free producers. A non-Marxian notion of exploitation is suggested to conclude.