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. Source: Wikipedia (en)