This chapter discusses the significance of Bernard Mandeville’s thesis that “private vices” yield “public benefit.” The causal connection between moral vice and economic gains proposed by Mandeville was contentious, but the impact he made was undeniable and lasting. Whether accepting his unsavory formula explicitly or not, the “moral” and the “economic” were embroiled in a century-long debate thanks to Mandeville, for which reason, his writings come first before others. As the chapter follows the debates about vices and their contribution to a desire-driven commercial society, it also presents a comprehensive picture of Mandeville as a writer of numerous works besides The Fable of the Bees. His Calvinist or Augustinian view of human nature’s innate corruption jarred against the later thinkers’ more positive view of human capacities, even as they partially adopted his thesis. In this regard, Mandeville can be said to be a “negative” initiator of a moral discourse of the economy that flourished in the century.