GEMARA

22b - Mishnah: A Sukah made on a camel is Kosher, but one may not go in it on Yom Tov.

23a: Our Mishnah is R. Meir:

Beraisa - R. Meir: A Sukah made on top of an animal is Kosher;

R. Yehudah disqualifies.

R. Yehudah learns from "Chag ha'Sukos Ta'aseh Lecha Shiv'as Yomim" - a Sukah that is not valid for all seven days is not a Sukah.

Question: What is R. Meir's reason?

Answer: He permits because mid'Oraisa it is valid. (Chachamim decreed not to use animals on Shabbos and Yom Tov lest one break off a branch while riding.)

27a - Beraisa - R. Eliezer: One may not go from one Sukah to another. One may not build a Sukah on Chol ha'Mo'ed.

Chachamim say, one may go from one Sukah to another, and one may build a Sukah on Chol ha'Mo'ed.

All agree that if a Sukah fell, one may rebuild it on Chol ha'Mo'ed.

R. Eliezer learns from "Chag ha'Sukos Ta'aseh Lecha Shiv'as Yomim" - a Sukah must be valid for all seven days.

Chachamim say, the verse permits to make a Sukah any time during the festival.

Question: Why must the Beraisa teach that all permit to rebuild on Chol ha'Mo'ed a Sukah that fell? This is obvious!

Answer: One might have thought that once it fell (according to R. Eliezer) the rebuilt Sukah is a new Sukah and it is not a Sukah for seven days. The Beraisa teaches that this is not so.

9a: Beis Shamai learn from "Chag ha'Sukos Ta'aseh Lecha Shiv'as Yomim" that a Sukah must be made l'Shem the Chag;

Beis Hillel use the verse to teach that one may make a Sukah during Chol ha'Mo'ed;

Beis Shamai hold like R. Eliezer, who says that one may not build a Sukah on Chol ha'Mo'ed.

RISHONIM

The Rif and Rosh (2:4) bring the Mishnah that permits a Sukah on a camel.

Ran (DH Masnisin): The Ritz Gei'us says that the Gemara establishes our Mishnah like R. Meir to teach that the Halachah does not follow it. The general rule is that the Halachah follows R. Yehudah against R. Meir. Others say that the Gemara merely shows that there is an argument. The Halachah follows a Stam Mishnah even when there is an argument in a Beraisa.

The Rif and Rosh (2:16) bring the argument of R. Eliezer and Chachamim.

Rambam (Hilchos Sukah 4:6): A Sukah made on a camel is Kosher, but one may not go in it on Yom Tov, for one may not go on an animal on Yom Tov.

Rambam (6:15): If one did not make a Sukah, whether he was Shogeg or Mezid, he makes one on Chol ha'Mo'ed. This is even if it is towards the end of the seventh day, for the Mitzvah applies all seven days.

Magid Mishnah: This is like Chachamim.

Ritva (23a DH Mai Taima): R. Yehudah agrees that the Isur to use animals on Shabbos is mid'Rabanan. Nevertheless, if there is any reason why a Sukah is not valid for all seven days, it is Pasul mid'Oraisa.

Ro'oh (brought in Hagahos to Ritva ibid., Mosad ha'Rav Kuk edition): It is like a Pesul mid'Oraisa.

Question (Sha'ar ha'Melech Hilchos Lulav 8:1 DH ume'Atah): According to R. Yehudah, how can the verse discuss a Pesul mid'Rabanan? Rather, R. Yehudah must expound like R. Eliezer, that the verse disqualifies mid'Oraisa a Sukah built during Chol ha'Mo'ed. He applies the verse to disqualify mid'Rabanan a Sukah on an animal. If so, why did the Gemara ask what is R. Meir's reason? He holds like Chachamim and Beis Hillel, who argue with R. Eliezer!

Answer #1 (Sha'ar ha'Melech, ibid.): The Beraisa did not establish the argument of R. Meir and R. Yehudah to be about whether or not the Sukah must be valid for seven days. This shows that this is not the argument.

Question (Sha'ar ha'Melech DH Ach): Why does the Ritz Gei'us rule like R. Yehudah against Beis Hillel, who permit to make a Sukah during Chol ha'Mo'ed?!

Answer to both questions (Aruch l'Ner 9a DH bi'Gmara): Beis Shamai transpose the verse and expound 'Sukah Ta'aseh l'Chag', make a Sukah l'Shem the Chag. Beis Hillel transpose it and expound 'Sukah Ta'aseh b'Chag', i.e. one may make a Sukah on Chol ha'Mo'ed. R. Eliezer holds like Beis Shamai. This enables him to learn from "Shiv'as Yomim" that a Sukah cannot be made during Chol ha'Mo'ed. Rather, it must be for all seven days. R. Yehudah and R. Meir hold like Beis Hillel, so they cannot expound this way. Rather, "Shiv'as Yomim" teaches that a Sukah must be valid for all seven days. Mid'Oraisa it excludes a Sukah that is Kosher only on Shabbos through Migo (since it is a wall for Shabbos, it is a wall for Sukah, e.g. Pasei Bira'os - 7a), or a Sukah that cannot stand in a normal wind (23b).

Ran (7a DH Garsinan): Anything prone to dry up within seven days to the point where it will give a minority of shade is Pasul even now (like air).

POSKIM

Shulchan Aruch (OC 628:3): A Sukah made on a camel is Kosher, but one may not go in it on Yom Tov.

Shulchan Aruch (637:1): If one did not make a Sukah, whether he was Shogeg or Mezid, he makes one on Chol ha'Mo'ed. This is even if it is towards the end of the seventh day.

Beis Yosef (DH v'Omrinan): Chachamim learn from "Chag ha'Sukos Ta'aseh Lecha Shiv'as Yomim" - one may make a Sukah any time during the seven days.

Rebuttal (Rashash 9a DH Gemara): If they learn from Shiv'as Yomim", why do they disagree with Beis Shamai, who expound "Chag ha'Sukos Ta'aseh", make a Sukah l'Shem the Chag! Rather, Chachamim also transpose the verse, but expound 'Sukah Ta'aseh b'Chag'. "Shiv'as Yomim" requires a Sukah to be valid for all seven days, like R. Yehudah and R. Meir. (R. Meir agrees that mid'Oraisa it must be valid - 23a.)

Shulchan Aruch (ibid.): One may go from one Sukah to another.

Rema (629:12): Anything that normally dries up within seven days is considered as if it is already dry. It is like air and disqualifies even from the side.

Mishnah Berurah (35): Since the Sukah cannot last for seven days, Chachamim decree to disqualify the Sechach immediately.

Eshel Avraham (13): The Levush says that we immediately disqualify anything that will dry within seven days until its shade will be a minority. We decree lest someone will be unable to make another Sukah and he will be Batel from the Mitzvah. It seems that this Pesul is mid'Rabanan. However, if it will dry and fall within seven days it is Pasul mid'Oraisa. Perhaps in the former case we do not decree at all, and it is Kosher as long as it is mostly shade (Mishbetzos Zahav 15).