Editing Synod of Whitby (section)

==Background==
{{See also|Celtic Christianity|Computus|}}
In seventh-century Britain there were several differences between Roman and Celtic Christianity.  One of these was the method of calculating the date of Easter.  The Celtic practice was that of the Gaelic monks associated with the isle of [[Iona]] and its extensive network of daughter-houses, where the monks still observed an 84-year Easter cycle (as had earlier been the rule in Gaul and in Rome), whereas the newer tradition which was kept in Rome by this time was a 19-year cycle which had been adopted from the church of Alexandria.  

In the kingdom of [[Northumbria]], these two traditions coexisted, and each had been encouraged by different royal houses. [[Edwin of Northumbria]] had converted to Christianity under the influence of [[Gregorian mission|missionaries sent from Rome]] by [[Pope Gregory I|Pope Gregory the Great]] and thus had established the 19-year Easter cycle in his realm. However, following his death and a year of political instability, [[Oswald of Northumbria]] gained the throne. He had learned Christian practice from the monks of Iona during his stay there (while a political exile in his youth), and had encouraged Ionan missionaries to further the Christianization of Northumbria, especially the famous Bishop [[Aidan of Lindisfarne|Aidan]].

The [[Synod]] of Whitby was convened to settle a [[Easter controversy|controversy about the correct method of calculating the date of Easter]]. [[Early Christians]] had probably originally celebrated Easter concurrent with the Jewish [[Passover]] (see [[Christian observance of Passover|Passover, Christian holiday]]), which was held on the [[Quartodecimanism|fourteenth day]] of the first lunar month of the Jewish year, called ''[[Nisan]]'', the day of the [[Death and resurrection of Jesus|crucifixion]] according to [[Gospel of John|John]] 19:14.  However, the [[First Council of Nicaea]] in 325 decreed that Christians should no longer use the Jewish calendar but should universally celebrate Easter on a Sunday, the day of the resurrection, as had come to be the custom in Rome and Alexandria.<ref name=conlet>{{Citation| author  = Constantine| author-link = Constantine the Great| chapter = Letter on the Keeping of Easter to those not present at Nicaea| orig-date = 325| editor  = Eusebius of Caesaria| editor-link = Eusebius of Caesaria| title  = The Life of Constantine| volume = III| publisher = Signature Books| at = §18–20| date = 1996| isbn = 1-56085-072-8|chapter-url=http://www.ccel.org/ccel/schaff/npnf214.vii.x.html}}</ref> Calculating the proper date (''[[computus]]'') was a complex process (involving a [[lunisolar calendar]]), and different calculation tables developed which resulted in different dates for the celebration of Easter.

In the 660s, Ionan adherents chose to continue using the 84-year Latercus cycle invented by [[Sulpicius Severus]] c. 410. Meanwhile, the [[Papal Curia]] had commissioned [[Victorius of Aquitaine]] (AD 457) and later [[Dionysius Exiguus]] (525) to produce a new reckoning, in order to resolve the differences between the Roman method and the more scientific method of the Alexandrian Church. The three reckonings often resulted in different dates for the celebration of Easter. Neither the Victorian or Dionysian reckonings were without problems. Dionysius had simply translated the Alexandrian system into Latin without understanding it. The Victorian system, confusingly, produced double dates, relying on the pope to choose which date to use. Nevertheless, the Victorian table was accepted widely outside the area of Irish influence. Around 602, the Irish missionary [[Columbanus|St&nbsp;Columbanus]] had already been condemned by a synod of French clerics for ignoring their authority and following his homeland's Easter calculations (the Victorian table was declared official in Gaul in 541). About AD 600 Columbanus wrote to [[Pope Gregory I]]: "You should know that Victorius has not been accepted by our teachers and by the old Irish experts and by the mathematicians most skilled in the calculation of the computus, but was considered more worthy of ridicule and pity than of authority."<ref>G.S.M. Walker (ed. and trans.), ''Sancti Columbani opera'' (Dublin, 1957), p. 7.</ref> But in Ireland also, debate raged over the best option for calculating the date of Easter.

The proper date of the celebration of the most significant Christian feast had already resulted in visible disunity in the Northumbrian court: Queen [[Eanfled of Deira|Eanfled]] of Bernicia and her court observed Easter on a different day than did King [[Oswiu of Northumbria|Oswiu]]. While one royal faction was celebrating Easter, the other would still be fasting during [[Lent]]. Nonetheless, the disunity did not result in problems as long as the well-respected Aidan was alive. After his death, his successor [[Finan of Lindisfarne|Finan]] found himself challenged by a monk named Ronan, an Irishman who had been trained in Rome and who wished to see the Roman Easter established. It was only in the time of [[Colmán of Lindisfarne|Colmán]], the third Ionan monk elected Bishop of Northumbria, that the conflict required royal attention and resolution.