Easter

=== First Council of Nicaea (325 AD) ===
{{main|First Council of Nicaea}}

This controversy between those who advocated independent computations, and those who wished to continue the custom of relying on the Jewish calendar, was formally resolved by the [[First Council of Nicaea]] in 325, which endorsed changing to an independent computation by the Christian community in order to celebrate in common. This effectively required the abandonment of the old custom of consulting the Jewish community in those places where it was still used. [[Epiphanius of Salamis]] wrote in the mid-4th century:

{{blockquote|[T]he [[Constantine I|emperor]]{{nbsp}}[...] convened a council of 318 bishops{{nbsp}}[...] in the city of Nicaea{{nbsp}}[...] They passed certain ecclesiastical canons at the council besides, and at the same time decreed in regard to the Passover [i.e., Easter] that there must be one unanimous concord on the celebration of God's holy and supremely excellent day. For it was variously observed by people; some kept it early, some between [the disputed dates], but others late. And in a word, there was a great deal of controversy at that time.<ref name = Epiphianus>Epiphanius, ''Adversus Haereses'', Heresy 69, 11,1, in {{cite book | last = Willams | first = F. | title = The Panarion of Epiphianus of Salamis Books II and III | publisher = E.J. Brill |date=1994 | location = Leiden | page = 331}}</ref>}}

Canons<ref>Apostolic Canon 7: "If any bishop, presbyter, or deacon shall celebrate the holy day of Easter before the vernal equinox with the Jews, let him be deposed." ''A Select Library of Nicene and Post-Nicene Fathers of the Christian Church,'' Second Series, Volume 14: The Seven Ecumenical Councils, Eerdmans, 1956, p. 594.</ref> and sermons<ref>St. John Chrysostom, "Against those who keep the first Passover", in ''Saint John Chrysostom: Discourses against Judaizing Christians'', translated by Paul W. Harkins, Washington, DC, 1979, pp. 47ff.</ref> condemning the custom of computing Easter's date based on the Jewish calendar indicate that this custom (called "protopaschite" by historians) did not die out at once, but persisted for a time after the Council of Nicaea.<ref name="McGuckin 2011 p.223 ">{{cite book | last=McGuckin | first=John Anthony | title=The encyclopedia of Eastern Orthodox Christianity | publisher=Wiley-Blackwell | publication-place=Maldin, MA | date=2011 | isbn=978-1-4443-9253-1 | oclc=703879220 | page=223}}</ref>

[[Dionysius Exiguus]], and others following him, maintained that the 318 bishops assembled at Nicaea had specified a particular method of determining the date of Easter; subsequent scholarship has refuted this tradition.<ref>{{cite book|last=Mosshammer|first=Alden A.|title=The Easter Computus and the Origins of the Christian Era|date=2008|publisher=Oxford University Press|location=Oxford|isbn=978-0-19-954312-0|pages=50–52, 62–65}}</ref> In any case, in the years following the council, the computational system that was worked out by the church of Alexandria came to be normative. The Alexandrian system, however, was not immediately adopted throughout Christian Europe. Following [[Augustalis (bishop)|Augustalis]]' treatise {{lang|la|De ratione Paschae}} (On the Measurement of Easter), Rome retired the earlier [[octaeteris|8-year cycle]] in favor of Augustalis' 84-year [[lunisolar calendar]] cycle, which it used until 457. It then switched to [[Victorius of Aquitaine]]'s adaptation of the Alexandrian system.<ref name="Mosshammer 2008 239–244">{{cite book|last=Mosshammer|first=Alden A.|title=The Easter Computus and the Origins of the Christian Era|date=2008|publisher=Oxford University Press|location=Oxford|isbn=978-0-19-954312-0|pages=239–244}}</ref><ref name="Holford-Strevens, Leofranc 1999 808–809">{{cite book|last1=Holford-Strevens |first1=Leofranc |last2= Blackburn |first2= Bonnie |title=The Oxford Companion to the Year|date=1999|publisher=Oxford University Press|location=Oxford|isbn=0-19-214231-3|pages=[https://archive.org/details/oxfordcompaniont00blac/page/808 808–809]|url=https://archive.org/details/oxfordcompaniont00blac/page/808}}</ref>

Because this Victorian cycle differed from the unmodified Alexandrian cycle in the dates of some of the Paschal full moons, and because it tried to respect the Roman custom of fixing Easter to the Sunday in the week of the 16th to the 22nd of the lunar month (rather than the 15th to the 21st as at Alexandria), by providing alternative "Latin" and "Greek" dates in some years, occasional differences in the date of Easter as fixed by Alexandrian rules continued.<ref name="Mosshammer 2008 239–244"/><ref name="Holford-Strevens, Leofranc 1999 808–809"/> The Alexandrian rules were adopted in the West following the tables of Dionysius Exiguus in 525.<ref name="Declercq 2000 p.143-144">{{cite book | last=Declercq | first=Georges | title=Anno Domini : the origins of the Christian era | publisher=Turnhout |location= Belgium | date=2000 | isbn=2-503-51050-7 | oclc=45243083 | pages=143–144}}</ref>

Early Christians in Britain and Ireland also used an 84-year cycle. From the 5th century onward this cycle set its equinox to 25 March and fixed Easter to the Sunday falling in the 14th to the 20th of the lunar month inclusive.<ref>{{cite book|last=Mosshammer|first=Alden A.|title=The Easter Computus and the Origins of the Christian Era|date=2008|publisher=Oxford University Press|location=Oxford|isbn=978-0-19-954312-0|pages=223–224}}</ref><ref>{{cite book|last=Holford-Strevens |first1=Leofranc |last2= Blackburn |first2= Bonnie|title=The Oxford Companion to the Year|date=1999|publisher=Oxford University Press|location=Oxford|isbn=0-19-214231-3|pages=[https://archive.org/details/oxfordcompaniont00blac/page/870 870–875]|url=https://archive.org/details/oxfordcompaniont00blac/page/870}}</ref> This 84-year cycle was replaced by the Alexandrian method in the course of the 7th and 8th centuries. Churches in western continental Europe used a late Roman method until the late 8th century during the reign of [[Charlemagne]], when they finally adopted the Alexandrian method. Since 1582, when the [[Roman Catholic Church]] adopted the Gregorian calendar while most of Europe used the Julian calendar, the date on which Easter is celebrated has again differed.<ref>{{cite web |title=Orthodox Easter: Why are there two Easters? |url=https://www.bbc.co.uk/newsround/48067272 |publisher=BBC Newsround |date=20 April 2020 |access-date=4 April 2021 |archive-date=23 December 2021 |archive-url=https://web.archive.org/web/20211223235240/https://www.bbc.co.uk/newsround/48067272 |url-status=live }}</ref>

The Greek island of [[Syros]], whose population is divided almost equally between Catholics and Orthodox, is one of the few places where the two Churches share a common date for Easter, with the Catholics accepting the Orthodox date—a practice helping considerably in maintaining good relations between the two communities.<ref>{{cite news | title=Easter: A date with God | url=http://www.economist.com/node/18584376 | date=20 April 2011 | newspaper=The Economist | access-date=23 April 2011 | quote=Only in a handful of places do Easter celebrants alter their own arrangements to take account of their neighbours. Finland's Orthodox Christians mark Easter on the Western date. And on the Greek island of Syros, a Papist stronghold, Catholics and Orthodox alike march to Orthodox time. The spectacular public commemorations, involving flower-strewn funeral biers on Good Friday and fireworks on Saturday night, bring the islanders together, rather than highlighting division. | archive-date=23 April 2018 | archive-url=https://web.archive.org/web/20180423192921/https://www.economist.com/node/18584376 | url-status=live }}</ref> Conversely, Orthodox Christians in Finland celebrate Easter according to the [[Western Christian]] date.<ref>{{cite news | title=Easter: A date with God | url=http://www.economist.com/node/18584376 | date=20 April 2011 | newspaper=The Economist | access-date=23 April 2011 | quote=Finland's Orthodox Christians mark Easter on the Western date. | archive-date=23 April 2018 | archive-url=https://web.archive.org/web/20180423192921/https://www.economist.com/node/18584376 | url-status=live }}</ref>