Gemara Clarity

Rosh Hashanah 21a

ראש השנה כ״א ע״א

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Topic

Keeping the calendar far from בית דין: two-day יום טוב, doubtful יום כיפור, leap years, and a moon-sign for burning חמץ

Overview

This amud is about how people far from בית דין kept the calendar. It opens by finishing an earlier point: two short months in a row would become well known. לוי came to בבל and saw people eating on the day that was really יום כיפור in ארץ ישראל. He would not testify, though, because he had not personally heard בית דין declare the month. רבי יוחנן ruled that places the ניסן messengers reach, but the תשרי messengers do not, must keep two days of פסח as a גזירה. He was upset when two of his students did not enforce it. Then come stories of doubt about יום כיפור: רבא fasted two days, and רב נחמן got news right at the end of his fast that he had to fast again. רב הונא בר אבין taught that a year is made a leap year if winter would last past the 16th of ניסן, based on "שמור את חדש האביב". Finally, רב נחמן gave sailors a moon-sign for burning חמץ, and the גמרא explains why it works on the 14th at sea.

Opening lines

תְּרֵי יַרְחֵי חַסִּירֵי

Two months that are made short

קָלָא אִית לְהוּ.

have a 'voice' to them, so it becomes known.

לֵוִי אִקְּלַע לְבָבֶל

Levi arrived in Babylonia

בְּחַדְסַר בְּתִשְׁרִי.

on the eleventh of Tishrei.

The steps (14)

  1. ResolutionTwo short months in a row would be well known
  2. Statementלוי sees the Babylonians eating on the real יום כיפור
  3. Statementלוי refuses to testify
  4. Statementרבי יוחנן's decree: keep two days of פסח where the תשרי messengers don't reach
  5. StatementTwo students see a town keeping one day and stay silent
  6. Conclusionרבי יוחנן gets upset and repeats his decree
  7. Statementרבא fasted two days of יום כיפור
  8. Statementרב נחמן hears that יום כיפור is tomorrow
  9. Statementרב נחמן's pained reaction
  10. StatementWhen to add a leap month
  11. ProofThe verse behind the leap-year rule
  12. Statementרב נחמן gives sailors a moon-sign for burning חמץ
  13. ChallengeThe full moon comes on the 15th, but חמץ is burned on the 14th
  14. ResolutionAt sea the moon already looks full on the 14th