Sunday, August 24, 2008

A Calendar for the whole Golah

Following up on the last post, we should ask, what does it mean that the Ibbur will become less during the stages before Moshiach's arrival, as it was during Galus Mitzraim?

Pirkei D'Rebbi Eliezer doesn't say that B'nei Yisrael did not practice Sod HaIbbur, it just says it was lessened. I would propose that the parallel between then and now could be the accuracy of our calendar.

Brief background: Our calendar is based on a 19 year cycle of lunar years, with 7 of these years having leap months. This is because 19 solar years is very close in length to 235 (19 * 12 + 7) lunar months. There is a set pattern of how we add leap months, and it created an accurate calendar, for its time, some 1600 years ago. Over time, however, the calendar has a drift, so that more and more years out of the 19 year cycle are too late.

In Rosh Hashanah 20b, Shmuel says that he can set up a calendar for the entire Golah. He doesn't mean the place; the calendar for Babylon and for Monsey are the same. Rather, Shmuel could make a calculation that would make a calendar that stays reasonably accurate until such time as a Sanhedrin could fix it. This is in our days.


  1. couldn't we say that the ibbur is nitma'et by the fact that the pre-ordained calendar (of Rabi?) is coming to an end?

  2. But what does that mean, coming to an end? It can go indefinitely, but more and more it will be against reality, in that leap years are supposed to be based on a relation to the Tekufat Nissan moment.

  3. the calendar in which kiddush haChodesh was done ahead of time..

    until when exactly does that calendar go?

    after that point, unless there's a sanhedrin, we won't be able to do kiddush haHodesh, which includes (i imagine) the actual act of ibbur.

    in other words we will know whether we should add a leap month, but we won't have the proper authority to do so.

  4. The calendar that we use has been in place since about 4119, 1649 years. It is based on a set cycle of leap years throughout the 19 year cycle. Mathematically speaking, these always met the rules laid down in the Gemara for leap years, at that time. Throughout the generations, error enters in, until the the situation that we have today. The calendar is still halachically valid, but that doesn't make it mathematically correct. The calendar can theoritically keep going indefinitely.

  5. Just curious - Did you mention this now due to the Pasuk of שמור את חדש האביב in Parshat Re'eh?

  6. It wasn't, but good guess regardless.