Written by Francis Barrett in 1801, The Magus is a collection of three books. Much of the material was actually collected by Barrett from older occult handbooks, as he hints in the preface:
With over 500 pages, It is a collected works of the most famous magicians, such as Zoroaster, Hermes, Apollonius, Simon of the Temple, Trithemius, Agrippa, Porta (the Neapolitan), Dee, Paracelsus, Roger Bacon, Sir Edward Kelly and a great many others...
Previous demonologists such as Binsfeld (1589) had drawn up lists that comprised a hierarchy of devils, and attributed them with the power to instigate people to commit the seven deadly sins. Lucifer was associated with Pride, Satan with Anger and so forth. In The Magus Barrett altered the "roster of devils" and Satan now became a prince of deluders (serving conjurers and witches).
Edited and illustrated by Edmund Kelly The Magus is a Grimoire that holds its place in occult literature.