"The Christian religion, which in itself is plain and simple, he confounded by the dotage of superstition. Instead of reconciling the parties by the weight of his authority, he cherished and propagated by verbal disputes the differences which his vain curiosity had excited. The highways were covered with troops of bishops, galloping from every side to the assemblies which they call synods; and, while they laboured to reduce the whole body to their own particular opinions, the public establishment of the posts was almost ruined by their hasty and repeated journeys." The "opinions" indeed were far from original to Constantius, but his support of Arianism rendered the position of the Church in the imperial city dangerous and uncertain. Five times was the bishop Paul banished from the city. The Catholics rose in tumult, and the streets of Constantinople saw for the first time what they have often since witnessed, a massacre in which not even the churches preserved those who fled to them for refuge. Another fatal precedent had already been set when Constantine died, by the murder of many princes of his house. One of the few survivors ascended the throne in 361, on the death of the last of Constantine's sons. This new Emperor was Julian, whom later ages have named the Apostate.

Julian had been baptized and had "followed the way of the Christians" till he was twenty. He had even, it seems, taken minor orders as a reader. But he was greatly attracted by the old Greek ideals, and had not patience to study the Christian religion perfectly. As Emperor he set himself seriously to revive Paganism, which had received its death-blow from Constantine.

The pagan Emperor was above all things a pedant and a doctrinaire. It is impossible to study his life or his writings without a sense of his extraordinary self-conceit. He was moral in life, sound and excellent even to weariness in his platitudinarian sentiments; but he was obstinate, and blind, and abnormally self-conscious, as men of his mould always are. He was so convinced that he was right that he was utterly blind to the good deeds of Christians and deaf to their arguments, even from the clearest thinkers. We see in him not a trace of intellectual progress, even on his own lines; we find him throughout intensely superstitious and fond of dabbling in occult arts. As a student, he somewhat hastily accepted certain conclusions, and found himself a marked man in consequence. From that moment he clung to his philosophy with the tenacity of a limited mind; and we may be quite sure the story is legendary that such a man admitted on his deathbed the triumph of a religious system which he had combated all his life.

Julian was brought up probably in Constantinople. As Emperor he did not a little to increase the pride and beauty of the city. Especially interesting to him were the constitutional rules which Constantine had set up in imitation of the old Rome, and he paid notable respect to the office of the Consul, and enlarged the powers of the Senate. Art and science he endeavoured to foster by endowments for teaching in the schools of the city, and in this he was followed by his successors. Julian died a disappointed man in 363, and his successors inclined to the Catholic party; but still Arianism was strong, and its strength was felt not least in Constantinople. Jovian proclaimed toleration, Valentinian followed him, Valens professed Arianism. While religions contended, the material prosperity of the city continued to grow. In 378, when the Goths drew near to besiege the imperial city, they turned back, it is said, at the sight of its increased size. Already people of every kindred and tongue poured into the great mart for commerce and pleasure. At length, says Sozomen, it far surpassed Rome both in population and riches, and Eunapius thus describes its importance in his day:—"Constantinople, formerly called Byzantium, allowed the ancient Athenians a liberty of importing corn in great quantities; but now not all the ships of burden from Egypt, Asia, Syria, Phœnicia, and many other nations can import a quantity sufficient for the support of those people whom Constantine, by unpeopling other cities, has transported thither." Already there began the custom, which has lasted so many centuries, of building houses on wooden piles thrust out into the sea. As the incursion of the barbarians became more dangerous many took refuge in the capital; and yearly the churches grew in importance, and the monasteries attracted more religious.

"There were many structures which Constantine had only commenced; and the completion of the fortifications of the city had been left to Constantius; Julian found it necessary to construct a second harbour on the side of the sea of Marmora;[1] Valens was obliged to improve the waterworks of the city by the erection of the fine aqueduct which spans the valley between the fourth and fifth hills. And how large a number of hands such work required appears from the fact that when the aqueduct was repaired, in the ninth century, 6000 labourers were brought from the provinces to Constantinople for the purpose."[2]

But while the magnificent aqueduct of Valens (364-378) still towers over the city, as one views it from the heights of Pera, no other great building was added till the reign of Theodosius the Great (378-395), which marks the triumph of Catholic Christianity and the great increase in the splendour of the patriarchal and imperial abode. A contemporary, Gregory of Nyssa, quaintly describes the results of the theological interests which now surrounded the throne. Not only did great preachers fill the churches with attentive crowds, but the poor took up the tale. "The city is full of mechanics and slaves who are all of them profound theologians, and preach in the shops and in the streets. If you desire a man to change a piece of money for you he informs you wherein the Son differs from the Father; if you ask the price of a loaf you are told by way of reply that the Son is inferior to the Father; and if you enquire whether the bath is ready, the answer is that the Son was made out of nothing." This was in the time of the Arian triumph. It was the work of great preachers, as well as of the orthodox Emperor, to recover the Church from the blows she had received in the house of her friends.

The three great saints of the Eastern Church in the fourth century were in different ways associated with Constantinople. S. Basil of Cæsarea in Cappadocia, (brother of S. Gregory of Nyssa) was a fellow-student of the Emperor Julian, and died in 379. He knew very little directly of the seat of empire; he probably only twice passed through it; but his writings, full in every page of lucid order and perspicuous exposition, did much to vindicate the position which the orthodox in Constantinople were struggling to retain. Probably it was before his death that the great preacher, S. Gregory of Nazianzus, was pleading in the imperial city, and vindicated by his great oration the worship of the Holy Trinity. The site of his first preaching was commemorated by the building of the Church of Anastasia, a name given to denote the rising again of the Catholic faith of Nicæa. The sixteenth century mosque of Mehmed Pacha, south-west of the Hippodrome, preserves the position of the church, which was destroyed in 1458. At first the mission of S. Gregory was conducted amid scenes of the greatest disturbance and at great danger to his own life. His church was profaned, he himself was stoned. But when Theodosius entered the city in triumph he gave to S. Gregory the great church of the Twelve Apostles, and himself sought to seat him upon the episcopal throne. Humble, and weakened by suffering, it was with reluctance that the saint entered upon the heritage of the church; but he records that when he entered the sanctuary the light that burst forth on the chill November day cheered him to give thanks before all the people for the benefits which the Blessed Trinity had bestowed. After a month of reluctance he was at length installed as bishop. In May 381 the second General Council of the Church was assembled by the order of the Emperor Theodosius at Constantinople. It reasserted the creed of Nicæa, emphasised the Catholic teaching of the Divinity of the Holy Ghost, and condemned the heresy of Apollinaris. Its claim to be ecumenical rests on its unanimous acceptance of "all the nations and all the churches of the Christian world."

By this council the precedence of the bishop of Constantinople in the Church was assigned as next after that of the Roman bishop, "because it is the new Rome."

S. Gregory, attacked by critics for his acceptance of the see, which he had so reluctantly received, withdrew to Nazianzus. "The title of a saint had been added to his name, but the tendencies of his heart, and the elegance of his genius, reflect a more pleasing lustre on the memory of Gregory of Nazianzen," says Gibbon in his inimitable way. The consecration of his successor, a senator named Nectarius, who when elected had not yet been baptised, is described by the same classic as "whimsical," but it served to bring peace to the Church of Constantinople. The conquests of Theodosius confirmed the security of the imperial throne, and under the rule of the orthodox Emperor the Church in the East regained her peace. By his order all churches were given up to the orthodox, and his edict condemned all those who taught heretical doctrines, and "who, though possessing a sound faith, form congregations separate from the canonical bishops." Under Theodosius the security of life and property in the imperial city tended to a great increase of wealth and population; and with that to a considerable extension of the area occupied.

"Should the zeal of the Emperor to adorn the city continue," said the orator Themistius, "a wider circuit will be required, and the question will arise whether the city added to Constantinople by Theodosius is not more splendid than the city which Constantine added to Byzantium."