On the Operation of Daemons

Michael Psellus’s treatise examines daemons within the framework of Byzantine Christian philosophy, classifying them and discussing their powers and modes of action. Its historical value lies in preserving a learned medieval view of intermediary spiritual beings, and readers will find a systematic, often surprisingly rational discussion of demonology rather than a manual of invocation.

Michael Psellus (1018–c. 1078) was a Byzantine scholar, philosopher, and court official whose writings included works on theology, philosophy, and the occult sciences. His treatises are an important source for medieval Byzantine demonology, magic, and learned esoteric lore.