Concept
The controversy over the correct date for Easter began in Early Christianity as early as the 2nd century AD. Discussion and disagreement over the best method of computing the date of Easter Sunday has been ongoing ever since and remains unresolved. Different Christian denominations continue to celebrate Easter on different dates, with Eastern and Western Christian churches being a notable example. Quartodecimanism Quartodecimanism (from the Vulgate Latin quarta decima in Leviticus 23:5, meaning fourteenth) is the practice of celebrating Easter on the 14th of Nisan at the same time as the Jewish Passover. Quartodecimanism caused two schisms, one headed by Blastus in Rome and one headed by Polycrates in the East. First Council of Nicaea#Separation of Easter computation from Jewish calendar In 325 an ecumenical council, the First Council of Nicaea, established two rules: independence from the Jewish calendar, and worldwide uniformity. However, it did not provide any explicit rules to determine that date, writing only “all our brethren in the East who formerly followed the custom of the Jews are henceforth to celebrate the said most sacred feast of Easter at the same time with the Romans and yourselves [the Church of Alexandria] and all those who have observed Easter from the beginning.” Shortly before the Nicean Council, in 314, the Provincial Council of Arles in Gaul had maintained that the Lord's Pasch should be observed on the same day throughout the world and that each year the Bishop of Rome should send out letters setting the date of Easter. Synod of Whitby The Roman missionaries coming to Britain in the time of Pope Gregory I (590–604) found the British Christians adhering to a different system of Easter computation from that used in the Mediterranean basin. This system, on the evidence of Bede, fixed Easter to the Sunday falling in the seven-day period from the 14th to the 20th of its lunar month, according to an 84-year cycle. The limits of Nisan 14 – Nisan 20 are corroborated by Columbanus.