Bede

Northumbria in Bede's childhood had two churches keeping Easter on different Sundays. The Irish mission that had converted the north used an older table for calculating the date; the Roman mission used the Alexandrian nineteen year cycle. A king could be feasting while his queen was still fasting through Lent. The Synod of Whitby in 664 decided for the Roman reckoning, and the technical discipline behind that decision, computus, became Bede's life work.

Computus is astronomy done for a liturgical purpose. Easter is fixed to the first Sunday after the first full moon on or after the spring equinox, which means predicting lunar months against solar years indefinitely into the future. Bede wrote a short handbook, De temporibus, in 703, and then the full treatment, De temporum ratione, in 725. It covers finger reckoning, the divisions of time, the moon's course, the leap year, the ages of the world, and one section that has nothing to do with Easter at all: a correct account of the tides as following the moon, including the observation that the time of high water differs along a coast.

The same discipline produced the dating system. Dionysius Exiguus had proposed counting years from the incarnation two centuries earlier and it had gone almost unused. Bede adopted it in his Easter tables and then throughout the Ecclesiastical History, and also counted backwards before it, which is the first sustained use of a scheme now in worldwide civil use.

The preface to the Ecclesiastical History is addressed to King Ceolwulf and does something almost no other early medieval historian does: it explains where the book came from. Bede names Albinus, abbot at Canterbury, as his chief authority for Kent, and Nothhelm, a London priest who searched the papal archives in Rome and copied out letters of Gregory the Great for him. He names bishops and monasteries who supplied the material for their own regions, and he asks the reader not to blame him if the account is wrong, since he has followed the common report of reliable men.

He then prints the documents. Letters from popes to kings and bishops appear in full rather than in summary, which is why several of them survive at all. It is a working method recognisable to a modern historian, and it is the reason the Ecclesiastical History is still read as evidence rather than only as literature.

The limits are real and should be said. He is writing to a purpose, the unification of the English church under Roman practice, and the Irish tradition he came to disagree with is treated respectfully but as mistaken. He reports miracles in quantity where they support a saint's cult.

He died at Jarrow in 735. His pupil Cuthbert wrote an account of it, describing him dictating the last sentence of an English translation of John's Gospel and finishing it before he stopped. His remains were later taken to Durham, where they lie in the Galilee chapel of the cathedral, and Leo XIII declared him a Doctor of the Church in 1899.