A heresy which was introduced into Spain towards the end of the 4th century by an Egyptian named Marcus. The system was based on the Gnostic–Manichaean doctrine of a two-fold principle of the world, one good, the other bad, and derived its name from Priscillian, who became its leader. The sect gradually assumed the form of a secret society and threatened to overrun the whole of southern Europe. Its peculiar doctrines and practises were examined in the synod of Saragossa in 380, and Priscillian and his followers were excommunicated. Violence was resorted to as a means of suppressing the heresy but without success. Finally, under Emperor Maximus, a synod was called at Bordeaux in 384. Priscillian was accused of practising magic, and he and several followers were condemned and executed while many others were exiled. The whole procedure was condemned by such men as Saint Ambrose, Saint Martin of Tours, and Pope Damasus. The heresy gradually died out at the end of the 6th century.