Italy, and threatened the bishops with his anger, if they should not purge their churches of the heresy. In East Illyria, which was important to Eome as the ecclesiastical outpost toward Constantinople, he succeeded in regaining and establishing the supremacy, which had been acquired by Damasus, but had afterward slipped away. Anas- tasius of Thessalonica applied to him to be confirmed in his office. Leo granted the prayer in 444, extending the jurisdic- tion of Anastasius over all the Illyrian bishops, but reserving to them a right of appeal in important cases, which ought to be decided by the pope according to divine revelation. And a case to his purpose soon presented itself, in which Leo brought his vicar to feel that he was called indeed to a participation of his care, but not to a plentitude of power {pleiiitudo potes- tatis). In the affairs of the Spanish church also Leo had an opportunity to make his influence felt, when Turibius, bishop of Astorga, besought his intervention against the Priscillianists. He refuted these heretics point by jDoint, and on the basis of his exposition the Spaniards drew up an orthodox regulajidei with eighteen anathemas against the Priscillianist error. But in Gaul he met, as we have already seen, with a strenuous antagonist in Hilary of Aries, and, though he called the secular power to his aid, and procured from the emperor § 63. LEO THE GREAT. 321 Valentinian an edict entirely favorable to his claims, he at- tained but a partial victory.' Still less successful was his efibrt to establish his primacy in the East, and to prevent his rival at Constantinople from being elevated, by the famous twenty- eighth canon of Chalcedon, to official equality with himself.' His earnest protest against that decree produced no lasting effect. But otherwise he had the most powerful influence in the second stage of the Christological controversy. He neu- tralized the tyranny of Dioscurus of Alexandria and the results of the shamefid robber-council of Ephesus (449), fiu'nished the chief occasion of the fourth ecumenical council, presided over it by his legates (which the Roman bishop had done at neither of the three councils before), and gave the turn to the final solution of its doctrinal problem by that celebrated letter to Flavian of Constantinople, the main points of which were in- coi'porated in the new symbol. Yet he owed this influence by no means to his office alone, but most of all to his deep insight of the question, and to the masterly tact with which he held the Catholic orthodox mean between the Alexandrian and An- tiochian, Eutychian and Nestorian extremes. The particulars of his connection with this important dogma belong, however, to the history of doctrine. Besides thus shaping the polity and doctrine of the churcli, Leo did immortal service to the city of Rome, in twice rescuing it from destniction." Wlien Attila, king of the Huns, the "scourge of God," after destroying Aquileia, was seriously threatening the capital of the