St. John Chrysostom, who had been patriarch of Constantinople, though he died in exile. This century also saw two ecumenical councils. The first was held in 431 at Ephesus and dealt with the perceived heresy of Nestorius, patriarch of Constantinople. The reaction against Nestorianism spawned a counter-heresy known as Monophysitism, a form of which was popularized by one of Nestorius’ own priests, Eutyches, who gave rise to Eutychianism. The rival heresy was dealt with at the Council of Chalcedon