I., pope from 422 to 432. At his accession the dissensions caused by the faction of Eulalius (see BONIFACE I.) had not yet abated. He, however, triumphed over them, and his episcopate was peaceful. When the doctrines of Nestorius were denounced to him, he instructed Cyril, bishop of Alexandria, to follow up the matter. The emperor Theodosius II. convoked an ecumenical council at Ephesus, to which Celestine sent his legates. He had some difficulties with the bishops in Africa on the question of appeals to Rome, and with the bishops of Provence with regard to the doctrines of St Augustine. To expedite the extirpation of Pelagianism, he sent to Britain a deacon called Palladius, at whose instigation St Germanus of Auxerre crossed the English Channel, as delegate of the pope and bishops of Gaul, to inculcate orthodox principles upon the clergy of Britain. He also commissioned Palladius to preach the gospel in Ireland which was beginning to rally to Christianity. Celestine was the first pope who is known to have taken a direct interest in the churches of Britain and Ireland. (L. D.*)