(Κύριλλος), ST., was a native of ALEXANDRIA, and nephew of Theophilus, bishop of the same place. The year of his birth is not known. After having been a presbyter of the church at Alexandria, he succeeded to the episcopal chair on the death of Theophilus, A. D. 412. To this office he was no sooner elevated than he gave full scope to those dispositions and desires that guided him through an unquiet life. Unbounded ambition and vindictiveness, jealousy of opponents, illdirected cunning, apparent zeal for the truth, and an arrogant desire to lord it over the churches, constituted the character of this vehement patriarch. His restless and turbulent spirit, bent on self-aggrandisement, presents an unfavourable portrait to the impartial historian. Immediately after his elevation, he entered with vigour on the duties supposed to devolve on the prelate of so important a city. He banished from it the Jews, who are said to have been attempting violence towards the Christians, threw down their synagogue and plundered it, quarrelled with Orestes, and set himself to oppose heretics and heathens on every side. According to Socrates, he also shut up the churches of the Novatians, took away all their sacred vessels and ornaments, and deprived Theopemptus, their bishop, of all he had. (Histor. Eccles. 7.7.) But his efforts were chiefly directed against Nestorius, bishop of Constantinople; and the greater part of his life was passed amid agitating scenes, resulting from this persevering opposition. In consequence of an epistle written by Cyril to the Egyptian monks which had been carried to Constantinople, Nestorius and his friends were naturally offended. When Cyril understood how much Nestorius had teen hurt by this letter, he wrote to him in justification of his conduct, and in explanation of his faith, to which Nestorius replied in a calm and dignified tone. Cyril's answer repeats the admonitions of his first letter, expounds anew his doctrine of the union of natures in Christ, and defends it against the consequences deduced in his opponent's letter. Nestorius was afterwards induced by Lampon, a presbyter of the Alexandrian church, to write a short letter to Cyril breathing the true Christian spirit.

In the mean time the Alexandrine prelate was endeavouring to lessen the influence of his opponent by statements addressed to the emperor, and also to the princesses Pulcheria, Arcadia, and Marinia; but Theodosius was not disposed to look upon him with a friendly eye because of such epistles; for he feared that the prelate aimed at exciting disagreement and discord in the imperial household. Cyril also wrote to Celestine, bishop of Rome, informing him of the heresy of Nestorius, and asking his co-operation against it. The Roman bishop had previously received some account of the controversy from Nestorius; though, from ignorance of Greek, he had not been able to read the letters and discourses of the Constantinopolitan prelate. In consequence of Cyril's statement, Celestine held a council at Rome, and passed a decree, that Nestorius should be deposed in ten days unless he recanted. The execution of this decree was entrusted to Cyril. The Roman prelate also sent several letters through Cyril, one of which, a circular letter to the Eastern patriarchs and bishops, Cyril forwarded with additional letters from himself. This circular was afterwards sent by John of Antioch to Nestorins. Soon after (A. D. 430), he assembled a synod at Alexandria, and set forth the truth in opposition to Nestorius's tenets in twelve heads or anathemas, A letter was also drawn up addressed to Nestorius another to the officers and members of the church at Constantinople, inciting them to oppose their patriarch, and a third to the monks. With these anathemas he sent four bishops as legates to Nestorius, requiring of him to subscribe them if he wished to remain in the communion of the Catholic church and retain his see. Celestine's letter, which he had kept back till now, was also despatched. But Nestorius refused to retract, and answered the anathemas by twelve anti-anathemas. In consequence of these mutual excommunications and recriminatory letters, the emperor Theodosius the Second was induced to summon a general council at Ephesus, commonly reckoned the third oecumenical council, which was held A. D. 431. To this council Cyril and many bishops subservient to his views repaired. The pious Isidore in vain remonstrated with the fiery Alexandrine prelate. Nestorius was accompanied by two imperial ministers of state, one of whom had the command of soldiers to protect the council. Cyril presided, and urged on the business with impatient haste. Nestorius and the imperial commissioners requested that the proceedings might be delayed till the arrival of John of Antioch and the other eastern bishops, and likewise of the Italian and Sicilian members; but no delay was allowed. Nestorius was condemned as a heretic. On the 27th of June, five days after the commencement of the council, John of Antioch, Theodoret, and the other eastern bishops, arrived. Uniting themselves with a considerable part of the council who were opposed to Cyril's proceedings, they held a separate synod, over which John presided, and deposed both Cyril and Memnon his associate. Both, however, were soon after restored by the emperor, while Nestorius was compelled to return to his cloister at Antioch. The emperor, though at first opposed to Cyril, was afterwards wrought upon by various representations, and by the intrigues of the monks, many of whom were bribed by the Alexandrian prelate. Such policy procured many friends at court, while Nestorius having also fallen under the displeasure of Pulcheria, the emperor's sister, was abandoned, and obliged to retire from the city into exile. Having triumphed over his enemy at Ephesus, Cyril returned to Egypt. But the deposition of Nestorius had separated the eastern from the western churches, particularly those in Egypt. In A. D. 432, Cyril and the eastern bishops were exhorted by the emperor to enter into terms of peace. In pursuance of such a proposal, Paul of Emesa, in the name of the Orientals. brought an exposition of the faith to Alexandria, sufficiently catholic to be subscribed by Cyril. He returned with another from Cyril, to be subscribed by the Easterns. This procured peace for a little while. But the spirit of the Alexandrian bishop could not easily rest; and soon after the disputes were renewed, particularly between him and Theodoret. In such broils he continued to be involved till his death, A. D. 444.

According to Cave, Cyril possessed piety and indomitable zeal for the Catholic faith. But if we may judge of his piety by his conduct, he is scarcely entitled to this character. His learning was considerable according to the standard of the times in which he lived. He had a certain kind of acuteness and ingenuity which frequently bordered on the mystical; but in philosophical comprehension and in metaphysical acumen he was very defective. Theodoret brings various accusations against him, which represent him in an unamiable and even an unorthodox light. He charges him with holding that there was but one nature in Christ; but this seems to be only a consequence derived from his doctrine, just as Cyril deduced from Nestorius's writings a denial of the divine nature in Christ. Theodoret, however, brings another accusation against him which cannot easily be set aside, viz. his having caused Hypatia, a noble Alexandrian lady addicted to the study of philosophy, to be torn to pieces by the populace. Cave, who is partial to Cyril, does not deny the fact, though he thinks it incredible and inconsistent with Cyril's character to assert that he sanctioned such a proceeding. (Suidas, s. v. Γ̔πατία.)