21. What day of the week it is on the kalends
THE RECKONING OF TIME
one would think ought to be the sixth according to the formula. This is because the Moon of the month of November loses a day and is considered complete with only twenty-nine [days] instead of the usual thirty.
/349/ In truth, all this is easier to teach by oral explanation than in writing. However, do not overlook the fact that some people begin this formula from September, giving the regular 5 to September, 5 to October, 7 to November, 7 to December, and for the rest, as we give it above. Because of the authority of the Egyptians,they act in a thoroughly reasonable manner so as to imitate, in the calculation of the beginning of the year, those from whom the art of calculation took its origin. But to others it seems much more appropriate and e⁄cient that all calculation, insofar as logical necessity presents no obstacle, should start from the beginning of their year, and continue onwards to the end of the year in a ¢xed and inviolable course: [this is the case] even among the Latins.
21. WHAT DAY OF THE WEEK IT IS ON THE KALENDS
They210 provide a handy formula, similar to [the previous] one, for ¢nding the [week]day of the kalends, so that by simply using another set of regulars, you may ¢nd the day of the week through the concurrents211 by means of this [formula], just as you found [the age of the Moon] through the epacts in the [previous formula].
January has a [solar] regular of 2, February 5, March 5, April 1, May 3, June 6, July 1, August 4, September 7, October 2, November 5,
December 7. These regulars indicate speci¢cally /350/ what the weekday of the kalends is in the year to which seven concurrents are assigned. For the other years, you add the number of concurrents noted for that particular year212 to the regulars of each month, and in this way you will ¢nd the day of the kalends without a mistake. Remember that when a leap year occurs, one of the concurrent days is dropped;
210 The Egyptians, presumably.
211 The concurrent is a number representing the weekday of 24 March. It is explained at greater length below, ch. 53. The concurrents function very much like the epacts
^ indeed, Bede also calls them ''solar epacts'' ^ in that they can be used with a monthly
''regular'' to determine the weekday of any date in the calendar. The ''regular'' is a number representing the constant di¡erence between the weekday of 24 March, and the weekday of the ¢rst day of the month in question.
212 These can be found in the Paschal table, or by using the formula given in ch.
54.