What is the size of a grogeret as expressed relating to a kav? A beitza? Kzayit?
Morris Smith
Shalom, Morris.
See Ronnie Figdor's chart on our site, at http://www.dafyomi.co.il/useful-resources.htm . Look for footnote references #20 and #52, and refer to the chart above it for all comparisons.
In short, 9 Gerogeres is a Se'udah (Eruvin 80b), which is either 3 or 4 Beitzim (Machlokes Tana'im in Eruvin 82b). A Beitzah is generally either 3.3, 3, or 2 Zeisim (See Shulchan Aruch OC 368:3, 468:1, Vilna Gaon to Mishlei 22:9), and a Kav is 24 Beitzim.
Best regards,
Mordecai Kornfeld
Kollel Iyun Hadaf
Is there a remark in shas that a seuda in 1/9 kav or am i wrong?
Also-how do poskim deal with shabbas 91 where it clearly says that a zayis is smaller than a grogeres? Many of the permutations you offer in your response will yield a grogeres as a small or equal shiur to a zayis
Morris Smith
(a) Eruvin 80b - 18 Gerogeres = 2 Se'udos.
(b) That is an excellent point. Tosfos addresses this point in Eruvin 80b DH Agav, and the Magen Avraham and Bi'ur ha'Gra expand on it in Orach Chayim 486.
Tosfos concludes, based on your question, that we do not rule like the opinions that a Se'udah is 3 or 4 Beitzim. We rule like another opinion regarding the size of a Se'udah - that of Rebbi Meir or Rebbi Yehudah. These opinions also are mentioned in the Mishnah in Eruvin 82b, but the Mishnah does not state clearly the exact size they attribute to a Se'udah. Perhaps their Se'udah is 9 Beitzim (or 12 Beitzim - Bi'ur ha'Gra). This makes the Gerogeres 1/2 Beitzah (or 2/3 Beitzah - Bi'ur ha'Gra).
The Rambam, though, rules clearly that 2 Se'udos = 6 Beitzah = 18 Gerogeres. This is indeed the source of the Bi'ur ha'Gra (ibid.) who concludes that according to the Rambam, a Zayis must be less than 1/3 Beitzah (since a Gerogeres is equal to 1/3 Beitzah).
The Magen Avraham (ibid.) suggests another approach to the Rambam. Even the Rambam's Zayis is between 1/2 and 1/3 Beitzah, which is indeed larger than a Gerogeres - which is 1/3 Beitzah. The Gemara in Shabbos which says that a Gerogeres is bigger than a Zayis is referring to small Zeisim.
Best wishes,
Mordecai Kornfeld