While the Emperor and his friends were thus busy with trifles, and the government was in the hands sometimes of wise ministers such as Leichudes, sometimes of mere thieves, the throne was constantly threatened by revolts (of which the most famous was that of George Maniakes) and by direct attacks on the city, such as that of the Russians, and in 1047 of Leo Tornikos. This latter was nearly successful. Many of the citizens were ready to join him, and but for the military skill shown by Constantine (if we rightly read the rhetorical description of Psellus) Leo would probably have entered and found himself welcomed as Emperor.

In 1054 Constantine X. died, and the aged Theodora, the last survivor of the Macedonian house, came forth again from her convent and reigned with the aid of ministers who were at least capable and honest. On her death, after two years as sole ruler, the throne passed, by her wish, to an able but aged soldier, Michael Stratioticus.

Psellus shows that the accession of this sovereign marked a crisis in the history of the Empire. Constantine X. had reformed the Senate, opening it to all men of merit apart from their birth. Michael VI. thought he could rely entirely on the civil functionaries, but the army was still strong enough to dictate to the Emperor, and his unwise acts led to an alliance between the generals and the energetic patriarch Michael Cerularius. Michael attempted to negotiate with Isaac Comnenus, whom the army had chosen as their leader, and who was encamped at Nicæa (Isnik); but before the envoys, among whom was Psellus, had completed their mission, a rising in the city, led by some discontented senators, had dethroned and slain Michael, and the whole city was waiting to welcome Isaac as Emperor.

Constantinople in this revolution decisively chose her own Emperor. The Senate and the chiefs of certain "clubs" (the successors of the factions of the Circus so prominent four centuries before) guided, as seems probable, by the patriarch, carried the city with them. Isaac they summoned from Skutari: Michael departed to a monastery with the patriarch's kiss of peace.

The scene when Isaac was about to cross the Bosphorus to receive his crown was a dramatic one. He called Psellus, the envoy of his deposed rival, to him, and said, when the philosopher spoke of the enthusiasm of the people, "I liked thy tongue better when it reviled me than now when it speaks smooth words." But he began his reign by an amnesty, for he made Psellus president of the Senate, and Michael the patriarch—however much he may have distrusted him—he treated with the fullest confidence and honour.

While these political and dynastic changes had supplied the Empire with a new ruler almost every year, the growing alienation between East and West had been marked decisively by the separation of the Churches. Two great names embody in the East the final protest against Roman assumption. The Church of Constantinople had never abandoned its claim to equality with that of Rome, though it allowed to the ancient city the primacy of honour. Photius, who became patriarch in 858, and died in 891, owed his throne to an election which was not canonical, and though a council in 861 at Constantinople, at which papal legates were present, confirmed him in his office, Pope Nicholas I. declared that its decisions were illegal, and that Photius was deposed and excommunicated, while the Emperor himself was attacked in language of peculiar vehemence. The papal claim to decide between two claimants to the patriarchate was fiercely resented. Photius declared the equality of his see with that of Rome. To the Roman claim of jurisdiction, complicated also by assertions of supremacy over the Bulgarian Church, were added points of theological contention which the churches debated with as much eagerness, and it would seem, as little desire, to arrive at a reasonable solution. The addition of the words Filioque to the Nicene Creed, asserting the Procession of the Holy Ghost from the Father and the Son, was, and is, resented by the Greeks as an addition to "the faith once for all delivered to the Saints." The use of unleavened bread in the Holy Eucharist was regarded in the East as an heretical innovation. There were, and are, other points of dispute; but none, it is probable, but for the strong national feeling of Italy and of Greece, would have caused a final breach.

The position which Photius defended with skill and vigour in the ninth century was reasserted by Michael Cerularius in the eleventh. He regarded the teaching of the West on the doctrine of the Holy Trinity, says Psellus, as an intolerable heresy; and he was prompt to reassert jurisdiction over the churches of Apulia, now conquered by the Normans and made subject to Rome. The final breach came from Rome itself. On July 16, 1054, two legates of the Pope laid on the altar of S. Sophia the act of excommunication which severed the patriarch from the communion of the West, and condemned what were asserted to be seven deadly heresies of the Eastern Church.

But to return to the imperial revolution.

Isaac Comnenus, who was called to the throne in 1057, had been brought up in the palace, but he was none the less a warrior and a man of determination, who had served the Empire well. He reigned only for two years, and then retired to end his days in religion, in the famous and beautiful monastery of the Studium, which looks from a slight elevation over the Sea of Marmora, some half mile away, and whose half ruined walls are to-day among the most striking of the memorials of the past that Constantinople can show.

With the beginning of the dynasty of the Comneni the causes which brought about the fall of the Empire can clearly be traced. The imperial power, concentrated more and more in the imperial household, and finally in the Emperor himself, had come to be devoted chiefly, in the hands of feeble or self-indulgent emperors, to the maintenance of imperial dignity and pride in the city itself. The magnificent administration which had presented a coherent and effective government while the rest of Europe was in "the dark ages," was beginning to sink into a mere machine for the support of a luxurious Court. The Empire was neglected. The aristocracy of Byzantium was treated with severity or contempt. The officials of the State were the mere nominees of the Emperor. For their interest and for the pursuit of popularity among the people it was that government seemed to exist. Every year, as the defences of the Empire grew weaker, the shows of the Hippodrome, the festivals of the Church, the entertainments of the palace, grew more splendid. When the other States of Europe were yet in their cradle, when England as a Power had hardly begun to exist, the long history of the Empire was verging irresistibly towards decay.