Controversy Regarding the Calendar

As we discussed last year, there is no disagreement regarding the dates of the Jewish Holidays; this fact is, in itself, a remarkable indication of the steadfastness of the Rabbinic traditions. Throughout history, there have been only a few controversies about the calendar.

In the Jewish year 4683 (922 C. E.), the Nasi (head of court) of the Beis Din in Yerushalayim, took a strong stance regarding the dating of Rosh Hashanah. The Geonim in Bavel (Babylon) disagreed.

Background

a. The Geonim of Bavel (Babylon)

Nebuchadnezzer had taken thousands of Jews captive during the Babylonian seizure of Eretz Yisrael. Since the days of Daniel and Yechezkel (Ezekiel), a large and vibrant Jewish colony lived in Bavel (modern-day Iraq). After the destruction of the Second Beis Hamikdash, the great Yeshivos were located in Bavel, and the final version of the Gemara (Talmud) was written there. A few generations later, the period of the Geonim commenced. The Geonim were the brilliant heads of academies, to whom all of Jewry looked for direction.

b. The Calendar Rules: Dechiyos

Originally, the court in Yerushalayim had the duty of declaring the new month. Eventually, however, the court relinquished this responsibility, and made public the calculations for the calendar.

Remember that the Molad is a calculated estimate for the new moon. It is not meant to be exact, but only estimates the average time for the Molad. Also, there are several rules which cause the Chodesh (month) to be moved away from the calculated time for the Molad.

For example:

1. If the calculated Molad would occur after noon, the beginning of the month is pushed off one day. 2. If the Molad occurs on the first, fourth, or sixth day of the week, again, the Molad is pushed off a day. Sometimes, both rules apply, and the month is pushed off for two days. For example, if the calculated Molad would be after noon on the third day of the week, the first rule causes the month to be pushed off until the fourth day. The second rule then pushes the day further -- until the fifth day.

The Calendar Controversy

In 4683, Rebbe Aharon ben Meir was the Nasi in Yerushalayim. His account differed from the calculation of the Geonim significantly. He decided that the time had come to reassert the authority of the court in Yerushalayim, and declared that Rosh Hashanah would occur on a Tuesday. The account of the Geonim produced a Thursday!

From Egypt, Rebbenu Sadya, who would later become Rav Sadya Gaon, protested vigorously to Rebbe Aharon ben Meir. Rav Sadya was concerned that the debate would divide Jewry. His arguments were to no avail; for a time, pockets of the Jewish People kept the Yomim Tovim at different dates. In the face of the united front of Rav Sadya in Egypt and all the scholars of Bavel, the argument of Rebbe Aharon ben Meir was forgotten, and sole authority returned to the academies of Bavel.

A contemporary author has claimed that the gist of the debate was the mathematical innovation of Rebbe Aharon ben Meir, and that historians have investigated the political overtones, but overlooked the real innovation.

Whether mathematicians find this of interest remains to be seen; history, however, has certainly not indicated that the math was the essential debate. Rebbe Aharon ben Meir claimed to have his own tradition, one that varied from the traditions of the Geonim. He claimed that the rule which pushes off the commencement of the month if the molad occurs after the morning, was not dependent on noon, but noon plus 642 parts (out of 1040) of an hour. In the particular year of the debate, the argument made a significant difference. To the Geonim, the commencement of Rosh Hashanah was put off to Wednesday, then -- applying the second rule -- to Thursday. To Rebbe Aharon ben Meir, Rosh Hashanah was not to be put off at all.

Any mathematical argument of Rebbe Aharon ben Meir has not been bequeathed to posterity, but extensive writing and quotes of Rav Sadya Gaon remain intact, and the force of his thought is as clear as ever. The Geonim were the direct bearers of the Mesorah -- tradition -- from the Amoraim (authors of the Talmud), who, in turn, had received the Mesorah in uninterrupted succession from Moshe Rebbenu himself. Rav Sadya is quoted as saying precisely the idea we had written in the beginning: The fact that not a single dispute emerged for six hundred years -- from the time the court relinquished its responsibility of declaring the new month -- is remarkable indication of the unity of the Jewish People and the Torah.

We have quoted Rebbenu Bachya's comments in Parshas Bo several times. He quotes the opinion of the Geonim, that the account for which the calendar is established is exactly the same one that has been used from the Receiving of the Torah itself. This same account -- not the sighting of witnesses -- was, and has always been, the sole means of determining the calendar and the Yomim Tovim. (Rebbenu Bachya, Shmos 12:2 and 13:10.)

Although not everyone concurs with Rebbenu Bachya regarding the sighting of witnesses -- as we will soon see -- nonetheless, all agree that the calculation for the calendar has been handed down from Mount Sinai. (Cf. Chazon Ish, 138:4).