It has been supposed by several ecclesiastical historians of repute that the Council of Nicaea expressly authorised the bishop of Alexandria to issue these preparatory notices to the authorities in the various churches of Christendom. The evidence for this opinion is lacking; but certainly, as a matter of fact, the judgment of Alexandria carried great weight. In the West, however, the general practice was that Metropolitans should determine the date, and announce the day to their suffragans. In the sixth century the Council of Orleans (A.D. 541) directs that if the Metropolitan were in doubt he should consult the Apostolic see (Rome), and act in accordance with its decision (can. 1). About one hundred years later it would appear from the fifth canon of the Council of Toledo (A.D. 633) that the Spanish Metropolitan bishops did not receive information as to the date of Easter from any external source. They are directed to enquire among themselves by letter three months before the Epiphany, and make the announcement; and the reason assigned for this canon is that erroneous Easter Tables had caused differences. To attempt anything like a detailed account of the varieties in the methods adopted for the determination of Easter which held their ground for a time, some in the East, some in the West, would be unsuitable in an introductory work like the present. The extraordinary persistence exhibited by the Celtic Churches of Britain and Ireland in maintaining for a long time their own method of computing Easter against the Roman method introduced by Augustine of Canterbury and his followers, is an important and interesting feature in the history of Christianity in these countries. It is enough here to say that the native Churches were not Quartodecimans (as has sometimes been incorrectly alleged), but were adhering to a cycle which they had received long before the Roman missionaries arrived in Britain[162]. We must here be content with briefly noticing some of the leading features in the history of the change which gradually led up to the adoption of the Nineteen-Year Cycle as modified and propounded by Dionysius Exiguus in the early part of the sixth century.