By Water & Blood

Chronology of the passion and lunar reckoning

And he suffers on the thirteenth before the Kalends of April, they having overshot by one evening—that is, in the middle of the night of the fourteenth of the moon.

For they anticipated and ate the Passover, as the Gospel says and as we have often said; they therefore ate the Passover two days before eating—that is, on the third evening, though it ought to have been on the fifth evening; for thus the fifth was the fourteenth.

And he is seized on that same third late in the day, which was the eleventh of the moon by night, the sixteenth before the Kalends of April; Thursday the thirteenth by day; by night the fourteenth, the fourteenth before the Kalends of April; the day before the sabbath, the fourteenth by day, the thirteenth before the Kalends of April; sabbath the fifteenth by day, the twelfth before the Kalends of April, as Sunday dawns, the fifteenth by night;

which was illumination of Hades and earth and heaven and equality of night and day, because of the fifteenth of the moon and the course of the sun; for both resurrection and equinox took place on the eleventh before the Kalends of April, about which the Jews, erring, made an intercalary day, as I said before.

And the reckoning of the fine calculation has hourly details, which falls every three years, a day being disputed among them;

for they add to the lunar course after the three hundred fifty-four days also four other hours each year, so as to make one day in three years.

Therefore among them five intercalary months are completed in fourteen years, because one hour is subtracted from the solar course of three hundred sixty-five days and three hours; for when the hours are added there become thereafter 365 days less one hour;

hence these, multiplying the fourteen years six times through the eighty-fourth year, in the eighty-fifth set one intercalary month, so that there are thirty-one months in the eighty-five years, which according to accuracy ought to be thirty-one months and twenty-one days and three hours.