Love Durham Cathedral?Donate now

Treasure of the Month

Highlighting some of our most precious historic artefacts, from manuscripts to jewellery.

June 2018 - Bede, De Ratione Temporum, Venice, 1505

Treasure of the Month for June, this Latin edition of Bede’s The Reckoning of Time, is the oldest printed copy of Bede’s works in Durham Cathedral’s Library collections: printed in Venice just over fifty years after the invention of Gutenberg’s press.


De Ratione Temporum was originally written in medieval Latin in the early 8th century and was referred to by Bede as his “little book about the fleeting and wave-tossed course of time”. The title is presumed to derive from the book’s prologue: “some time ago I wrote two short books in a summery style which were, I judged, necessary for my students; these concerned the nature of things and the reckoning of time”.


Although better known as a historian – and creator of the Ecclesiastical History of the English People – the Venerable Bede's greatest scientific achievement was undoubtedly the creation of the western calendar, based upon the tables which had originally been conceived by the sixth-century Egyptian Dionysius Exiguus. These tables were designed to be used in calculating the date of Easter according to a 19 year lunar cycle, after which cycle the same Easter dates would occur. Prior to Bede’s work, the date of Easter could be calculated using any one of a wide variety of different tables, each one based on a different criteria for what constituted a valid Easter date, or different projections of cyclic recurrence – or both.

Before Bede, calendar literature was characterised predominantly by these tables. Where text was included it typically took the form of a polemic defending the system against a rival interpretation. De Ratione Temporum was unique in establishing the credibility of a system by establishing it within a comprehensive manual and theory of time reckoning. Bede’s arguments were so effective that it was this way of calculating Easter which was chosen at the synod of Whitby in 664, rejecting the rival method of the Northumbrian Church and therefore bringing them into line with the rest of Europe. Bede adopted and authorised the Dionysian method and added 'Anno Domini' dates to it; thus, not only did he define for the future the Church's method for the calculation of Easter, but he also played a major part in establishing 'AD' as the normal system for dating in Europe.


Bede also used this work on the calendar and the seasons to assist his scriptural interpretation: he argued that the fourth of the six days of Creation, for example, must have been 21st March (the vernal equinox – as the sun and moon must have been created ‘perfect’); and that the darkening of the sun at the Crucifixion must have been a miracle and not an eclipse, as an eclipse would have been impossible at the time of the Passover full moon.


This fascinating book will be on display on Saturday 16th June in the Cathedral’s beautiful Refectory Library as part of our Treasures of Durham Cathedral Library: Inventors and Innovators event. More information and online booking for this event is available here: