De praestigiis daemonum
The book also contains a famous appendix also circulated independently as the Pseudomonarchia daemonum, a listing of the names and titles of infernal spirits, and the powers alleged to be wielded by each of them. Weyer relates that his source for this intelligence was a book called Liber officiorum spirituum, seu liber dictus Empto Salomonis, de principibus et regibus demoniorum ("The book of the offices of spirits, or the book called Empto, by Solomon, about the princes and kings of demons.) Weyer's reason for presenting this material was not to instruct his readers in diabolism, but rather to "expose to all men" the pretensions of those who claimed to be able to work magic, men who "are not embarrassed to boast that they are mages, and their oddness, deceptions, vanity, folly, fakery, madness, absence of mind, and obvious lies, to put their hallucinations into the bright light of day." Weyer's source alleged there were estimated to be 7,451,926 devils, divided into 1111 legions and obeying 72 infernal princes. Weyer's source claimed that Hell arranged itself hierarchically in an infernal court which is divided into princes, ministries and ambassadors.
The book is remembered for two things. While Weyer held to a demonology that was entirely orthodox in terms of its endorsement of the reality of Satan and evil demonic spirits, while maintaining at all times that their ability to act was circumscribed by the omnipotence of God, he disagreed with certain of his contemporaries about the justification of witch-hunting. Weyer believed that most, probably all, cases of alleged witchcraft resulted from delusions of the alleged witch, rather than actual, voluntary cooperation with spiritual evil. In brief, Weyer claimed that cases of alleged witchcraft were psychological rather than supernatural in origin.
- Mora, George (November 1963). "On the 400th anniversary of Johann Weyer's "De praestigiis daemonum"--Its significance for today's psychiatry". The American Journal of Psychiatry (American Psychiatric Association) 120 (5): 417–428. doi:10.1176/ajp.120.5.417.
- Johann Weyer, De Praestigiis daemonum (Basel: Oporinus, 1563)
- Joseph H. Peterson, The lesser key of Solomon: lemegeton clavicula Salomonis (Weiser, 2001; ISBN 1-57863-220-X), pp. xiii - xiv
- qui se magos jactitare non erubescunt, curiositas, præstigiæ, vanitas, dolus, imposturæ, deliria, mens elusa, & manifesta mendacia, quinimo non ferendæ blasphemiæ, omnium mortalium, qui in mediæ lucis splendore hallucinari nolint....
- Number of demons: Monstrous.com website.
- Johann Weyer, Pseudomonarchia Daemonum, ed. by Joseph H. Peterson
- Stuart Clark, Thinking with demons: the idea of witchcraft in early modern Europe (Oxford University Press, 1999; ISBN 0-19-820808-1), pp. 198 - 202
- Peterson, supra