Jacquier argued in his bookA Scourge for Heretical Witches that witchcraft is a heresy, and, as such, the persecution of witches is justified. "Jacquier conceives of witchcraftprincipally in terms of a heretical cult: to him it is the 'abominable sect and heresy of wizards,' in which demons, not witches play the leading role." He also denied that the Canon Episcopi, which had been invoked to undermine witches' claims to supernatural feats including night flights, was relevant in the contemporary debate regarding the supposed powers of witches. The text is dated is 1458 but was first printed in 1581 together with a reprint of Thomas Erastus'sRepetitio disputatio de lamiis seu strigibus.