The hypothesis of the following essay is that any relationship, even a friendship, is asymmet-ric. At the beginning of the essay, I will analyse asymmetry as the basis of any exchange.Where surplus and subtraction are viewed as interactions’continuous plateaux. I will focus onsurplus and subtraction as a way of local strategizing with no general Strategy. Homer’s Ulysses is the paradigm of subtraction (Metis) while Shakespeare’s Portia the one of surplus(Mercy). As Marcel Mauss (1990), Georges Bataille (1976) and other authors claim: the gift isnever free. Subtractions and surplus are always constitutive parts of the exchange, even thoughthe surplus is not always exploitation (as seen with Portia) and the subtraction is not alwayssubmission (as in Ulysses). This implies that the rational exchange, in which I sell yousomething and you buy something from me – providing an adequate quantity of goods,money, or else – is utopic and ideological. The aim of the essay is to support a trans-disciplinary investigation concerning the exchange and to approach asymmetry fromdifferent scientific and literary perspectives, an essay on what Gilles Deleuze (1997) called “critical and clinical”. So literary critics and clinical approach are mingled, both of them belong to “life as we know it ” (Bérubé 1998).