1)

(a)Since Raban Yochanan ben Zakai instituted after the Churban Beis Hamikdash, that they would accept the witnesses all day, says Rabah, the Takanah of two days became Batel - in which case Rosh Hashanah became like every other Yom-Tov, and an egg that is laid on the first day, is permitted on the second.

(b)Abaye queried this from Rav and Shmuel - who lived after the Churban, yet they ruled that it is forbidden.

(c)We reconcile Rav and Shmuel with Raban Yochanan ben Zakai - by establishing the latter by the Bnei Eretz Yisrael, and the former to the Bnei Chutz la'Aretz, whose Minhag to keep two days was never broken, and who therefore continue to keep Yom-Tov as a Takanah (and not merely as a Safek).

2)

(a)Rav Yosef disagrees with Rabah - according to him, even after Raban Yochanan ben Zakai rescinded the Takanah of two days by Rosh Chodesh, the Takanah of two days by an egg remains, because it was a 'Davar she'b'Minyan' (something that was decided by a majority ruling), and a Davar she'b'Minyan cannot be rescinded by a second Beis-Din unless they are superior in knowledge and in number.

(b)Rav Yosef learns from the Pasuk in Yisro ...

1. ... "Lech Emor Lhem, Shuvu Lachem l'Oholeichem" (following "Heyu Nechonim li'Sheloshes Yamim, Al Tigshu el Ishah") - that something that was forbidden through a Beis-Din (in this case, it is Hash-m who issued the decree, and who then rescinded it) does not automatically become permitted, even when the reasons for the decree become obsolete, but need to be specifically rescinded.

2. ... "bi'Meshoch ha'Yovel, Heimah Ya'alu va'Har" (following "Gam ha'Tzon v'ha'Bakar Al Yir'u el Mul ha'Har ha'Hu" - the same Derashah as we learned from "Lech Emor Lahem, Shuvu Lachem l'Oholeichem". The proof from "Lech Emor Lahem ... " however, is inconclusive, since Hash-m's command there, might have been issued in the form of a command (to fulfill the Mitzvah of Onah with their wives - whereas the Heter to return to them did not perhaps, require a specific command).

(c)The indication that the prohibition to ascend the mountain ought not to apply anyway after the departure of the Shechinah (but which is nevertheless not automatically dissolved) - lies in the words "Gam ha'Tzon v'ha'Bakar Al Yir'u el Mul ha'Har Hahu", which implies that it is only forbidden to graze on the mountain as long as it is that mountain (i.e. whilst the Shechinah is on it, but not once It has departed).

(d)We learn that it is not the place of a person that honors him, but the person who honors the place - from the same Pesukim of "el Mul ha'Har ha'Hu" and "bi'Meshoch ha'Yovel, Heimah Ya'alu ba'Har", from which we see that Har Sinai was only holy as long as Hash-m's Shechinah was on it, but that the moment It departed, the Kedushah departed from the mountain, too.

3)

(a)The Torah gives the owner of Kerem Reva'i the option of - either bringing his fruit to Yerushalayim and eating it there b'Taharah, or of redeeming it, and of taking the money to Yerushalayim and spending it there.

(b)We learn this Din from a Gezeirah-Shavah "Kodesh" "Kodesh" from Ma'aser Sheni.

(c)Chazal instituted that - people who lived within a radius of one day's journey from Yerushalayim were obligated to take the fruit itself to Yerushalayim, and not to redeem it. The reason for this was in order to adorn the markets of Yerushalayim with fruit.

4)

(a)Rebbi Eliezer wanted to declare his vineyard Hefker for the poor - because the vineyard in question was east of Lud (which was the western extremity of one day's radius from Yerushalayim), and he could not take the trouble to take all the grapes to Yerushalayim.

(b)His disciples told him that his colleagues (meaning Raban Yochanan ben Zakai - his Rebbe) had already rescinded the decree to bring all the fruit to Yerushalayim (and that it was therefore unnecessary to declare the vineyard Hefker).

(c)We deduce from their words - that despite the fact that, after the Churban of the Beis Hamikdash, the reason for the decree no longer applied, it was nevertheless necessary to specifically rescind it (and that it was not automatically dissolved).

(d)We need this third proof that 'Davar she'b'Minyan, Tzarich Minyan Acher l'Hatiro' - to teach us that this principle extends even to Rabbinical decrees, too.

5)

(a)The egg remain Asur, according to Rav Yosef - because Raban Yochanan ben Zakai only rescinded the Takanah of Eidus (when the witnesses arrived after Minchah-time), but not that of the egg.

(b)Abaye objects to this, on the grounds that there was no specific decree regarding an egg - only that of testimony, and the Din of egg follows that of testimony. Consequently, once the decree of testimony has been rescinded, the egg on Rosh Hashanah automatically adopts the same Din as on every other Yom-Tov (like Rabah argues on Amud a).

(c)Rav Ada and Rav Salmon agree with Abaye, but rule like Rav Yosef, (though not for the same reason as him) - because, they say, we are worried that if we permit the egg this year when there is no Beis Hamikdash, then perhaps by next year, the Beis Hamikdash will be built, and people will think that just as last year, the egg was permitted on the second day, so too, will it be permitted this year. They will not of course realize that last year, since there was no Beis Hamikdash, the two days of Rosh Hashanah had two Kedushos, whereas this year, now that the Beis Hamikdash has been rebuilt, it only has one Kedushah.

(d)We are not by the same token, worried that if, at the time when there is no Beis Hamikdash (and there is therefore no Shir in which to err), the witnesses are permitted to testify all day, they may do the same after the Beis Hamikdash has been rebuilt - because testimony (unlike the Din of egg, which lies in the hands of each individual) is controlled by Beis-Din (who are unlikely to err).

6)

(a)Rava disagrees with Rabah, who contended that we should permit the egg nowadays from Raban Yochanan ben Zakai's second Takanah, because - even if he did reinstate accepting the witnesses after Minchah, who said that if they came after Minchah, the first day was Kodesh and not the second?! The truth of the matter is, that even after the Takanah - in order not to break with the original Takanah completely, they would still treat the second day as Yom-Tov (L'Chumra - even though originally, when this happened, it was the second day that was declared the real Yom-Tov, and the first day that was Yom-Tov only L'Chumra).