Patriarch of the West, and _primus inter pares_ in relation to the other
spiritual heads of Christendom, the bishop of Rome had gradually
claimed, on the strength of his occupying the _cathedra Petri_, a
position which approximated more and more to that of supremacy over the
whole Church. This claim had never been admitted in the East, but the
appeals which were made from Constantinople to his judgment and
authority, both at the time of the iconoclastic controversy and
subsequently, lent some countenance to its validity.

But the great advance was made in the pontificate of Nicholas I
(858-867), who promulgated, or at least recognized, the _False
Decretals_. This famous compilation, which is now universally
acknowledged to be spurious, and can be shown to be the work of that
period, contains, among other documents, letters and decrees of the
early bishops of Rome, in which the organization and discipline of the
Church from the earliest time are set forth, and the whole system is
shown to have depended on the supremacy of the popes. The newly
discovered collection was recognized as genuine by Nicholas, and was
accepted by the Western Church. The effect of this was at once to
formulate all the claims which had before been vaguely asserted, and to
give them the authority of unbroken tradition. The result to Christendom
at large was in the highest degree momentous. It was impossible for
future popes to recede from them, and equally impossible for other
churches which valued their independence to acknowledge them. The last
attempt on the part of the Eastern Church to arrange a compromise in
this matter was made by the emperor Basil II, a potentate who both by
his conquests and the vigor of his administration might rightly claim to
negotiate with others on equal terms. By him it was proposed (A.D. 1024)
that the Eastern Church should recognize the honorary primacy of the
Western patriarch, and that he in turn should acknowledge the internal
independence of the Eastern Church. These terms were rejected, and from
that moment it was clear that the separation of the two branches of
Christendom was only a question of time.

Already in the papacy of Nicholas I a rupture had occurred in connection
with the dispute between the rival patriarchs of Constantinople,
Ignatius and Photius. The former of these prelates, who was son of the
emperor Michael I, and a man of high character and a devout opponent of
iconoclasm, was appointed, thr