This articles focuses on a significant change to the curriculum in “ethics” (moral philosophy) in the University of Naples, superintended by Celestino Galiani, the rector of the University (1732–53), and Antonio Genovesi, Galiani’s protégé and the University’s professor of ethics (1746–54). The article contends that Galiani’s and Genovesi’s sympathies lay with the form of “modern natural law” pioneered by Hugo Grotius and his followers in Northern Europe. The transformation of curricular ethics in Protestant contexts had stemmed from an anxiety about its relevance in the face of moral skepticism. The article shows how this anxiety affected a Catholic context, and it responds to John Robertson’s contention that Giambattista Vico’s use of “sacred history” in his Scienza nuova (1725, revised in 1730 and 1744) typified a search among Catholics for an alternative to “scholastic natural law”, when the latter was found insufficiently to explain the sources of “human sociability.”