The Flagellum haereticorum fascinariorum (The Scourge of Heretical Bewitchers) was written by the Dominican inquisitor Nicolas Jacquier in 1458. Jacquier wrote the text to combat a sect of diabolical witches, the fascinarii, who worshipped demons at nocturnal “synagogues” and performed terrible crimes with demonic aid. The Flagellum was also aimed at those who did not believe in the physical reality of the sect or of interactions between humans and demons. This thesis, the first English-language work to examine the Flagellum in detail, traces Jacquier’s argument and endeavours to understand how his text was shaped within, and also helped shape, the cultural structures of late-medieval Burgundy. / Jacquier’s argument can be loosely divided into four parts. The first section defines the ways in which demons relate to humans, concluding that demons can act to delude humans both within the body, and through real, bodily interaction in the external world. The second section attacks the argument, based on the famous Canon Episcopi, that the fascinarii are simply deluded spiritually by the interior manipulation of demons. The reality of a demonworshiping sect raised questions about God’s omnipotence and benevolence. The Flagellum’s third part therefore elaborates a theology of divine permission based on the metaphor of the scourge to argue that God justly permits demonic action in the world. The final chapters of the tract turn to the legal dilemmas raised by the fascinarii. Jacquier argues that the fascinarii freely choose to sin and addresses difficulties associated with the possibility of demonic interference in witness statements. / Alongside my description of Jacquier’s argument, I have endeavoured to situate the Flagellum within the cultural structures of late-medieval Burgundy. I examine how the Flagellum can be read alongside a tale from the Cent Nouvelles Nouvelles to reveal tropes of demonic deception within fifteenth-century Burgundian courtly texts. I explore the possibilities of interpreting the Flagellum’s treatment of gender within the Dominican reform movement, with its focus on external and communal piety. I interpret the symbolic language of the scourge and trampling within Christian cultural structures of redemption through abasement. Setting the tract in dialogue with fifteenth century Burgundian art, I begin the task of understanding the ways in which time is organised within the Flagellum through an examination of scholastic epistemology. Finally, I situate arguments about the fascinarii and free will within debates over free will and determinism. The result of these discussions is an appreciation of the Flagellum’s immersion in interrelated cultural structures of bodily reality, sight, time and knowledge. / Through this analysis, I locate the study of witchcraft within a wider cultural history, uniting the interpretation of Burgundian art, literature and theology with an intensive study of the Flagellum.