The latest possible date of Passover is the 18th of Nîsân. If full moon falls on this day, and it is a Sunday, the year is a leap-year, the new moon by which you calculate, i.e. the new moon of Adhâr Secundus, falls on the 5th of the Syrian Adhâr, and the 8th of the same month is that Monday which follows after this new moon and falls the nearest to it, because in this case the 1st of the Syrian Adhâr is a Monday. Therefore the beginning of Lent is the 8th Adhâr, which is at the same time the latest possible date for the beginning of the Terminus Jejunii.
If we were to go back upon the new moon of Adhâr Primus, we should find that it falls on the 5th Shubâṭ in a common year, whilst the 1st Shubâṭ is a Sunday. In that case the preceding Monday would be nearest to it (the 2nd Shubâṭ), which is the beginning of the Terminus Jejunii. Now, this day would be suitable to be the beginning of Lent, if it also corresponded to all the other conditions (but that is not the case); viz. if we make this day the beginning of Lent, Fast-breaking would fall about one month earlier than Passover; and this is not permitted, according to a dogma of theirs. And if the year were a leap-year, new moon would fall on the 4th Shubâṭ, and then the preceding Monday, being the nearest to it, would be the 1st Shubâṭ, and this date does not lie within the Terminus Jejunii (2nd Shubâṭ—8th Adhar). Therefore we must disregard this new moon and fall back upon the following one.
The followers of Christ wanted to know before-hand the Passover of the Jews, in order to derive thence the beginning of their Lent. So they consulted the Jews, and asked them regarding this subject, but the Jews, guided by the enmity which exists between the two parties, told them lies in order to lead them astray. And besides, the eras of both parties differed. Finally, many of the Christian mathematicians took the work in hand and made calculations with the various cycles and different methods. Now, that method which they at last agreed to adopt, is the table called Χρονικόν, of which they maintain that it was calculated by Eusebius, Bishop of Cæsarea, and the 318 bishops of the Synod of Nicæa.
