Like many medieval texts for the use of magicians, this handbook is a miscellany rather than a systematic treatise. It is exceptional, however, in the scope and variety of its contents—prayers and conjurations, rituals of sympathetic magic, procedures involving astral magic, a catalogue of spirits, lengthy ceremonies for consecrating a book of magic, and other materials.
With more detail on particular experiments than the famous thirteenth-century Picatrix and more variety than the Thesaurus Necromantiae ascribed to Roger Bacon, the manual is one of the most interesting and important manuscripts of medieval magic that has yet come to light.
Richard Kieckhefer is Professor of Religion and History at Northwestern University and an acknowledged expert on medieval magic and witchcraft. His publications include European Witch Trials: Their Foundations in Popular and Learned Culture, 1300–1500 (1976), Repression of Heresy in Medieval Germany (1979), Unquiet Souls: Fourteenth-Century Saints and Their Religious Milieu (1984), and Magic in the Middle Ages (1990).