Ghosts are the perfect messengers from the afterlife – they’ve been there, after all! This paper discusses the role of groups of ghosts as didactic messengers in the medieval Latin West. As the doctrine and theological justification of Purgatory developed over the course of the eleventh and twelfth centuries, churchmen turned to the dead to provide legitimacy and support to their messages about the afterlife. But an explanation of the structure of the afterlife was not the only message that they put into the mouths of the dearly departed.

The dead became mouthpieces for the emerging Church reform movement, arguing against the pillaging of monasteries and lay interference in the leadership of the Church. They exposed their own sins, and threatened or cajoled the living into providing them with relief from their sufferings, through the power of donations to the Church and intercessory prayer. This paper looks at the role of a monk often seen in scholarship as secondary to the primary reformers of his day, Otloh of Saint Emmeram (c. 1010–c. 1072), and examines his Liber Visionum (Book of Visions), to see how he sought to use penitent ghosts to influence wider society. It also discusses the importance of networks to the burgeoning reform movement, through the works and movements of monks close to Otloh.