Trithemius was esteemed as the most learned man of his age, and wrote extensively on cryptography, alchemy, angelic magic, witchcraft, history, theology, and philosophy. An avid bibliophile, he collected thousands of volumes for his monastery's library, taking a special interest in arcane, obscure, and infamous books. This volume presents, for the first time in English, his fascinating compilation of treatises on the properties of magical amulets. These offer systematic and detailed descriptions of the design, properties, and powers of hundreds of images fashioned from stones of various kind. Also included is his Bibliotheca Necromantica (taken from his Antipalus Maleficiorum, or Shield Against Witches). This tract comprehensively lists and describes the various occult, necromantic, and magical volumes which Trithemius either possessed or had read, and offers an astonishing insight into the underground occult literature in circulation in Europe in the late Middle Ages.