[1] Continuing a tradition of Christian scholarship exploring the correct date of Easter, a generation later, Bede sought to explain the ecclesiastical reasoning behind the Synod of Whitby's decision in 664 to favor Roman custom over Irish custom.
[3] The treatise includes an introduction to the traditional ancient and medieval view of the cosmos, including an explanation of how the Earth influenced the changing length of daylight, of how the seasonal motion of the Sun and Moon influenced the changing appearance of the new moon at evening twilight, and a quantitative relation between the changes of the tides at a given place and the daily motion of the Moon.
[4] The Reckoning of Time describes the principal ancient calendars, including those of the Hebrews, the Egyptians, the Romans, the Greeks, and the English.
[5] The focus of De temporum ratione was calculation of the date of Easter, for which Bede described the method developed by Dionysius Exiguus.
According to the introduction by Faith Wallis in the 1999 English translated edition of The Reckoning of Time, Bede aimed to write a Christian work that integrated the astronomical understanding of computing with a theological context of history.
Here, Bede gives an exhaustive overview of the date of the Earth's creation, the months, the weeks and the Moon.
The Third Age is said to be 942 years long according to both the Hebrew Bible and Septuagint spanning from Abraham to David.