I take it for granted that the passion was on Friday the 14th day of the month Nisan, the great feast of the Passover on Saturday the 15th day of Nisan, and the resurrection on the day following. Now the 14th day of Nisan always fell on the full moon next after the vernal Equinox; and the month began at the new moon before, not at the true conjunction, but at the first appearance of the new moon: for the Jews referred all the time of the silent moon, as they phrased it, that is, of the moon’s disappearing, to the old moon; and because the first appearance might usually be about 18 hours after the true conjunction, they therefore began their month from the sixth hour at evening, that is, at sun set, next after the eighteenth hour from the conjunction. And this rule they called Jah, designing by the letters * and * the number 18.

I know that Epiphanius tells us, if some interpret his words rightly, that the Jews used a vicious cycle and thereby anticipated the legal new moons by two days. But this surely he spake not as a witness, for he neither understood Astronomy nor Rabbinical learning, but as arguing from his erroneous hypothesis about the time of the passion. For the Jews did not anticipate, but postpone their months: they thought it lawful to begin their months a day later than the first appearance of the new moon, because the new moon continued for more days than one; but not a day sooner, lest they should celebrate the new moon before there was any. And the Jews still keep a tradition in their books, that the Sanhedrim used diligently to define the new moons by sight: sending witnesses into mountainous places, and examining them about the moon’s appearing, and translating the new moon from the day they had agreed on to the day before, as often as witnesses came from distant regions, who had seen it a day sooner than it was seen at Jerusalem. According to Josephus, one of the Jewish Priests who had ministered in the temple, tells us that the Passover was kept on the 14th day of Nisan, according to the moon, when the sun was in Aries.