Nowadays when people hear the words “moveable feast” they are likely to think of noted author Ernest Hemingway’s stories of his time in Paris in the 1920s. Moveable feasts, however, are very important in genealogy. Many dates in pre-eighteenth century documents are stated in terms of feast days. These are church holidays, many used to commemorate the various men and women the Church desired to honor. Started by the Catholic Church, it was continued by the Anglicans when they splintered from the Catholic Church.
Some of these feast days are fixed. Examples are the feast days for the Venerable Bede (May 25), Joan of Arc (May 30), and Mary Magdalene (July 22). Others are “moveable feasts.” These feasts occur on different dates, depending on certain variables. The most significant of the moveable feasts is Easter Sunday.
The date for Easter Sunday changes on every year. On any given year it can occur as early as March 21 or as late as April 25. The origin of this celebration lies with pagan celebrations of the goddess Eoster. The early Catholic church joined the stories of the Passion and Resurrection of Jesus to the pagan festivals honoring Eoster. Thus the date became locked to the lunar calendar. It falls on the first Sunday after the first full moon that occurs on or after the vernal equinox. The equinox usually falls on March 21.
Other feast days occur in relation to Easter. Thus the change of the date of Easter impacts Ascendsion Day, Whitsunday, and Trinity all change based on the date of Easter. Because of these moveable feasts, the dates on documents or mentioned in documents can vary widely. Whitsunday, for example, falls on Pentecost, that is, the seventh Sunday after Easter. In 2012 that was may 27, in 2013 it was May 19, and in 2014 it will be June 8.
When reading an old document, it is important to know whether or not a feast day named is moveable. If it is a moveable feast, you will have to determine what day the feast fell on by doing the calculations for determining the feast day.
You must be careful to calculate properly when converting from a moveable feast day reference to an actual date. When recording these dates in your family, it is best to record the actual stated reference, putting the translated date in square brackets afterwards. And example would be:
John Smith and James Jones appeared in court for an altercation that occurred between the two of them on Whitsunday [29 May], 1569.
Recording the date this way ensures that you have the correct date in your records.