Felix Hemmerlin (1388-c.1460), who authored the works in this posthumously published collection, was a Swiss canon lawyer and Church reformer. His Opuscula et tractatus deals with demonology and witchcraft with surprising tolerance for the period; while others attacked witches as evil beings working on the Devil’s behalf, Hemmerlin acknowledged the usefulness of certain forms of magic. This book in particular contains tracts that deal with witchcraft and demonology based on the idea that it was the Devil, not the witches working for him, who was reprehensible for misfortune and evil in the world.                                                                                                                                    

Common blessings, charms, and spells were—according to Hemmerlin—often harmless and could even be beneficial, such as the cure for sick cows and the exorcism for pests that are both contained in this volume. The displayed section of this text features the introduction to Hemmerlin’s Incipit Tractatus de Exorcismis (or Here Begins the Tract Concerning Exorcisms), wherein Hemmerlin discusses such views on spellcasting.