Cyril of Alexandria

Cyril became Patriarch of Alexandria in 412, when the city stood at the apex of its power in the Roman Empire. He wrote extensively and threw himself into the Christological wars of his age, becoming the central force at the Council of Ephesus in 431 - where he excluded his rival John of Antioch for arriving late and secured the deposition of Nestorius as Patriarch of Constantinople. He expelled Novatians and Jews from Alexandria, and historians still argue over whether he inflamed the mob that murdered the philosopher Hypatia. Around 425 he adopted a 19-year lunar cycle for his Paschal table, dedicating it to Emperor Theodosius II; that cycle would surface a century later as the backbone of Dionysius Exiguus' calculations. He died in 444, venerated as a Doctor of the Church and the "Seal of all the Fathers" - though the Nestorian bishops at Ephesus had branded him heretic.