 A common theological topic for the authors of the School of Salamanca was the need to resist what they considered to be Lutheran heresies (Skinner 1978: 135–173). They suspected, for instance, that connecting legal authority to the virtue of princes could “inveigle away the hearts of simple men from due obedience to their princes and their priests”, as Vitoria put it (De potestate ecclesiastica I qu. 1, art. 2; transl. Vitoria 1991b: 55); and they regarded as heretical the view that grace is not increased directly by the sacraments ex opere operato but requires the faith of the recipient (De potestate ecclesiastica I qu. 2, art. 2). Other points at issue were whether all Christians could be seen as priests (ibid., II qu. 2, art. 1), the role of papacy, the veneration of the Virgin Mary, and the central problem of free will, which was denied by Luther. As we shall see, the problem of free will and grace also gave rise to an extremely bitter and long-lasting controversy inside Catholicism after the Council of Trent between Dominicans and Jesuits.