Career
Is most well known for the writing the Compendium Maleficarum (Book of Witches). Before 1441 there were various monasteries that were canonically recognized under the name ‘Fratres Sancti Ambrosii ad Nemus’ but there was little link between them. However, in 1441 Pope Eugene IV merged them into one congregation called ‘Congregatio Sancti Ambrosii ad Nemus’ of which Francesco Maria Guazzo was a member under the papacy of Pope Sixtus V and Pope Paul V.
On another occasion Guazzo was called to Düsseldorf in order to exorcise the mad Duke Johann Wilhelm of Julich and Kleve and Berg (1562–1609).
Guazzo first diagnosed possession, but after five months of unsuccessful attempts at spiritual healing and in the summer of 1604, the diagnosis was changed to bewitchment as the cause of the poor Duke’s mental illness.
Within his text, Guazzo discusses witches’ pacts with the devil, detailed descriptions of witches’ powers and poisons and also prepared his classification of the demons based on a previous work by Michael Psellus.
