From the days of the earliest Paleolithic cave rituals, magic has gripped the imagination. Magic and magicians appear in early Babylonian texts, the Bible, Judaism, and Islam. Secret words, spells, and incantations lie at the heart of nearly every mythological tradition. But for every genuine magus there is an impostor. During the Middle Ages, religion, science, and magic were difficult to set apart. The Middle Ages also saw the pursuit of...