[Avodah] Yom Tov Sheni for Olim LeReget to the Beit Mikdash

[Micha Berger]

The way I see things, RRW and RZS take it as obvious that the first to
use any form of fixed calendar was when Hillel Nesi'ah and his Sanhedrin had
to provide for the future impossibility of Sanhedrin convening and
accepting eidim.

I was taught that too. Bar Ilan searching didn't turn up a maqor, so I
asked the chevrah if they had proof. Abayei, who gives the "minhag
avoseihem beyadeihem" statement was niftar in 335 CE, within Hillel
Nesi'ah's leadership -- 330-365. The window is possible, if Abayei was
discussing events he lived through toward the last 5 years of his life.
AND, that Hillel Nesi'ah's Sanhedrin established the calendar during the
first 5 years of its meeting, not the other 30 closer to the crisis
that closed it in 425 (90 years after Abayei's death).

I'm just repeating the uncertainty I wrote about on Sep 11th
<http://lists.aishdas.org/pipermail/avodah-aishdas.org/2009q3/013412.html>,
before that thread became a discussion of Adar sheini rather than when
was rosh chodesh.

However, I think I found a quote that actually addresses the question,
so that we don't have to rely on our own blank-slate reasoning.

Rabbeinu Bechaye on Shemos 12:2. A teaser, "umeiheikh hay qov'im
chadashim al pi re'iyas halevanan, ela vadai iqar hamitzvah bekasuv al
pi hacheshbon". Or, in case that was too much transliteration to follow,
"and from where [do you know] that they established the months according
to the sighting of the moon; rather certainly the iqar of the mitzvah
in the text is according to the calculation."

Clearly the calculation evolved during the period of Chazal. RRW brought
numerous examples, but I do not recall if they were on-list and just not
in the latest digest yet, or private email. So, I'll give one he didn't.
Megillah niqreis (Megillah 1:1) isn't compatable with "lo bedu Pesach",
since it allows for Purim to fall out on any day of the week.

However, R' Chananel appears to say that some calculation or another was
always the central way of determining Rosh Chodesh, and this is actually
the intent midiOraisa.

This still leaves room for sefeiqa deyoma, as people in Bavel may not
know the latest cheshbon in use, or whether it was changed. A weak
teirutz, but all I have so far.

Tir'u baTov!
-Micha

-- 
Micha Berger             Like a bird, man can reach undreamed-of
micha at aishdas.org        heights as long as he works his wings.
http://www.aishdas.org   But if he relaxes them for but one minute,
Fax: (270) 514-1507      he plummets downward.   - Rav Yisrael Salanter