Rosh Hashanah 25

Calendars are political.

Futzing with the calendar is a dangerous business. Communities with mismatched calendars cannot come together at the most important moments, and people who observe festivals on the “wrong” day could be accused of serious violations. Perhaps because of these concerns, Rabban Gamliel, the leader of the rabbinical court, did not mess around. On calendrical matters, no dissent was allowed at all.

As we have discussed, a new month was declared when two witnesses came to the court and gave sworn testimony that they had seen the new moon in the night sky. The mishnah on today’s daf records a time when witnesses gave testimony about lunar observations that were clearly not physically possible: A new moon was seen one night, but on the next night there was no moon at all. Rabbi Dosa ben Horkinas scoffed at this testimony, saying: Can a woman give birth one day and be visibly pregnant the next?

But Rabban Gamliel declared a new month anyway. Why he did this is not clear; rabbis by this time did have calendrical calculations at their disposal, and Rabban Gamliel — the man who had moon charts in his attic — may have been using witness testimony as a way of legitimizing mathematical decisions he might have made anyway. Alternatively, he may have decided for the sake of deciding — either because the calendar was too important to mess with or because of his personality. Regardless of the reason, a showdown was about to take place.

When Rabbi Yehoshua challenged the ruling, Rabban Gamliel responded decisively. Rather than entertaining the alternate position, and doubtless knowing that what he had declared did not match the astronomical evidence, he ordered Rabbi Yehoshua to publicly denounce his own position by appearing before Rabban Gamliel with his staff and money on the day that, according to Rabbi Yehoshua, should have been Yom Kippur

In other words, Rabban Gamliel ordered Rabbi Yehoshua to violate Yom Kippur on the day that Rabbi Yehoshua and all their colleagues knew to be the “correct” date for that holiday.

What was the right thing to do? Two rabbis spoke with Rabbi Yehoshua and encouraged him not to resist — and offered him textual grounds for conceding to Rabban Gamliel. For Rabbi Akiva, the fact that the Bible says that festivals are what “you should proclaim” (Leviticus 23:4) suggests that calendrical power is vested in humans, not God — even if those humans are wrong. Even Rabbi Dosa, who had criticized Rabban Gamliel’s logic using the memorable analogy of a pregnant woman, admitted that the ruling should stand — because if it did not, what was to prevent a second-guessing of all rulings going back to Moses?

And so, Rabbi Yehoshua did what he was told:

Rabbi Yehoshua took his staff and his money in his hand, and went to Yavne to Rabban Gamliel on the day on which Yom Kippur occurred according to his own calculation. Rabban Gamliel stood up and kissed him on his head. He said to him, “Come in peace, my teacher and my student: my teacher in wisdom, and my student in accepting my position.”

The Talmud, in unpacking this story, dilutes it somewhat, suggesting that Rabban Gamliel was not making a case for the power of his personal authority over the movement of heavenly bodies, but simply enacting a different understanding of what was physically possible. At the same time, the Talmud also defends Rabban Gamliel by suggesting that leaders need not be great on an absolute scale; they just need to be the best that the era has to offer.

This wasn’t the first time we’ve seen Rabban Gamliel wield authority like a bludgeon, particularly against Rabbi Yehoshua. Remember Berakhot 27 and Berakhot 28? It didn’t end so nicely in that case. Nor was the fight we read about here the last of its kind in Jewish history. In 921 and 922 CE, a bitter calendrical dispute played out between the leaders of the Palestinian and Babylonian Jewish communities, in which latter disputed the calendar announced by the former.

The dispute seems to have been years in the making. The Palestinian rabbis had traditionally been responsible for the calendar, but over time the Babylonian academies — which were much larger — started to question that authority, perhaps under the influence of Abbasid astronomy, a discipline in which several rabbis of the era were actively engaged. Remnants of the dispute have been found in both the Cairo Genizah and the writing of Saadiah Gaon, who was once thought to have come to public prominence by means of this dispute. Previous studies suggested that the dispute ended in Tishrei 922 with a clear Babylonian victory, but recent scholarship led by Sacha Stern suggests that the truth is much messier: Saadiah was not the major player in this story, and the conclusion wasn’t really conclusive after all.

Read all of Rosh Hashanah 25 on Sefaria.

This piece originally appeared in a My Jewish Learning Daf Yomi email newsletter sent on November 3rd, 2021. If you are interested in receiving the newsletter, sign up here.

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Summary of Tractate Rosh Hashanah

Rosh Hashanah deals not just with the Jewish New Year, but also with questions of how the Jewish calendar is decided.