MS 291 and the Computation of Easter

MS 291, f. 3r
MS 291, f. 3r

While today we simply have to struggle to adapt to the one-hour difference when the clocks change before enjoying a convenient bank holiday weekend, our medieval predecessors struggled to reach a consensus as to when Easter fell in the year, and how to pinpoint it. In the early Middle Ages, constructing a calendar was complicated not just by the need to make the lunar and solar calendars agree, but also to reach an accord between Roman and Jewish measurements of time, which were both crucial to knowing when Biblical events occurred in the year and across history.  In response to this, church scholars developed a combination of mathematics, theology and science, called computus, to determine the date of Easter, which was often the source of controversy among church leaders- perhaps most famously leading to the Synod of Whitby in 664.

CCCC MS 291 is a compilation of material concerning the reckoning of time, written at St Augustine’s, Canterbury in the late eleventh or early twelfth century.  Towards the end, it also contains a full Easter table for 1064 to 1595, a complete Dionysiac Great Paschal Cycle (532 years, the product of the 19-year lunar cycle and the 28-year cycle of days of the week).

One of the most influential computus texts throughout the Middle Ages, Bede’s eighth century work, De temporum ratione, is included in MS 291. In it, Bede discusses the solar calendar and how to calculate the Paschal tables. The text focuses on practical methods, and works through progressive mathematical concepts, beginning with basic methods of addition, multiplication, and division, and proceeding through different ways of counting time, including methods such as the Greek zodiac.

MS 291, f. 22r- Eostre
MS 291, f. 22r

Bede’s text is also the only witness to the name of the Anglo-Saxon deity who gave her name to the month of April: Eostre. Eostremonath was the original name of the closest temporal equivalent to the Roman month of April, and, according to Bede, was a time to honour the goddess. With the arrival of the Christian holiday, the Anglo-Saxon name was applied to the new holy event, while the Roman name gained precedence for the fixed month.

The texts contained in MS 291 thus cross through the disciplines of astronomy, myth, history, religion, science and maths- all in the pursuit of accurately celebrating Easter. Explore the manuscript yourself at Parker on the Web.

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