A conversation with Alessandra Bucossi (Ca' Foscari University) on the preoccupation with heresy in the twelfth century, which resulted in the production of a number of massive anti-heretical treatises. We discuss the historical context of their production, the empire's increasing engagement with the Latins and Armenians, whose Churches deviated from that of Constantinople in certain points, and the function of these works. The conversation is based on a team project on this topic that Alessandra headed up, which we will discuss in more detail in the sequel episode.