Prior to the notion that power could and must be offset by that same power, it had at length been thought that the only way to neutralise a passion was to counterbalance it with another passion. This chapter explores how, in the same way but before this particular idea had crystallised, the concept that it was just—and in a certain sense inevitable—to resort to one monopoly to counter another had already emerged in theological-juridical circles. The monopoly concealed the exercise of an innately tyrannical power and posed a threat to both the correct operation of exchange and the very survival of the res publica. Monopoly was a sin and a crime; despite this, both theologians (chiefly Dominicans and Jesuits) and, later, jurists too acknowledged the legitimacy of the monopolium versus monopolium mechanism.