De praestigiis daemonum
De praestigiis daemonum, translated as On the Tricks of Demons, is a book by medical doctor Johann Weyer, also known as Wier, first published in Basel in 1563.
The book argues that witchcraft does not exist and that those who claim to practice it are suffering from delusions, which should be treated as mental illnesses, rather than punished as witchcraft. It was influential in the abolishment of witchcraft trials in the Netherlands.
It was one of the principal sources of Reginald Scot's sceptical account of witchcraft, The Discoverie of Witchcraft.
Content
Weyer disagreed with certain 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.
The book 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 claimed that Hell arranged itself hierarchically in an infernal court which is divided into princes, ministries and ambassadors.
Publication
De Praestigiis was first published in Basel in 1563. It has been translated into English, French, and German.
Reception and legacy
Weyer’s book challenged the views of his contemporaries, and it was not well received or understood by his peers. The majority of established academics criticized and rejected De praestigiis Daemonum. Weyer was told by his friends that his book must be destroyed or rewritten, while his enemies speculated that he was a lunatic.
Jean Bodin’s famous 1580 book about the dangers of witchcraft, De la démonomanie des sorciers, includes a lengthy rebuttal of De praestigiis, arguing that witch trials are necessary and providing methods for testing witches.
However, the contemporary view toward Weyer's theories changed dramatically along with the development of psychology and psychiatry from the 1800s onward and the book is now considered "a precursor of modern psychiatry."
Early editions of the book are extremely valuable and often sell for thousands of dollars at antiquarian auctions.