Tell me a ghost story
“Black books,” as they were often called, came into usage around the 13th century. They were possessed not only by magicians and sorcerers but also by physicians and noblemen - or anyone who thought he had something to gain with a little help from a demon. Ideally, the grimoire was copied by hand.
The Encyclopedia of Witches and Witchcraft by Rosemary Ellen Guiley, 1999.