(Mishnah - R. Meir): When the 14th falls on Shabbos (we cannot do Bi'ur at the proper time, the sixth hour on Erev Pesach), so we do Bi'ur before Shabbos;

Chachamim say, Bi'ur is done in its proper time. (Mishnah Berurah 444:15-21 - some permitted methods on Shabbos are scattering crumbs where they will be trampled on or swept, giving or selling it to Nochrim, Bitul and covering with a Keli [until after Yom Tov, when he will burn it], and casting it into a latrine.)

R. Eliezer bar Tzadok says, we Meva'er Terumah before Shabbos [only Kohanim can eat it - we are unlikely to find new people to eat it] and Chulin in its time.

(Gemara - Beraisa - R. Eliezer bar Tzadok): Once, my father was in Yavneh and the 14th was on Shabbos; Zunin, the appointee of R. Gamliel told us that it was time to do Bi'ur; I followed my father and we did Bi'ur.

(Mishnah): If one was on his way to a Mitzvah, i.e. to slaughter Korban Pesach, circumcise his son, or eat Seudas Kidushin (a meal celebrating engagement) in his father-in-law's house, and he remembered that he has Chametz in his house:

If he has time to return to his house, do Bi'ur, and return to the Mitzvah, he must do so;

If not, he does Bitul in his heart [and does the Mitzvah].

If Yisraelim are in danger on account of Nochrim, a raging river, a fire or a house that collapsed, and one is heading to save them, he does Bitul in his heart.

If one is going to make Shevisah (Rashi - Eruv Techumim, Tosfos - to lodge elsewhere on Yom Tov) of Reshus (not for the sake of a Mitzvah), he returns immediately.

Similarly, if one left Yerushalayim and remembered that he is carrying Kodesh meat (it became Pasul upon leaving):

If he already passed Tzofim (i.e. he is too far away to see the Mikdash), he burns it where he is;

If not, he returns to burn it in front of the Mikdash (alternatively - in Har ha'Bayis), from wood designated for the Ma'arachah (the fire on the Mizbe'ach).

Question: What quantity [of Chametz or meat] obligates one to return?

Answer #1 (R. Meir): The quantity for both of them is k'Beitzah;

Answer #2 (R. Yehudah): The quantity for both of them is k'Zayis.

Answer #3 (Chachamim): The quantity for Kodesh is k'Zayis, the quantity for Chametz is k'Beitzah. (Tosfos - we are more lenient about Chametz, for one can Mevatel it.)

(Gemara - Beraisa) Contradiction: If one was going to his father-in-law's house for Seudas Kidushin, or was heading to make Shevisah of Reshus, he returns immediately.

Resolution #1 (R. Yochanan): Our Mishnah is R. Yosi; the Beraisa is R. Yehudah:

(Beraisa - R. Yehudah): Seudas Kidushin is Reshus;

R. Yosi says, it is a Mitzvah.

(Rav Chisda): All agree that the first meal is a Mitzvah - they argue about the second meal [that is eaten with Sivlonos, i.e. nice Kelim that one sends to his betrothed].

This suggests another resolution.

Resolution #2: The Mishnah and Beraisa are both R. Yehudah - the Mishnah discusses the first meal, the Beraisa discusses the second.

(Beraisa - R. Yehudah): I only heard that Seudas Kidushin is a Mitzvah, but not Seudas Sivlonos;

R. Yosi says, I heard that Seudos Kidushin and Sivlonos are both Mitzvos.

(Beraisa - R. Shimon): A Chacham may not benefit from any meal which is not a Mitzvah.

Question: What is an example?

Answer (R. Yochanan): This is a meal celebrating the marriage of a Bas Kohen to a Yisrael (she should have married a Kohen; Maharsha - Chachamim are called Kohanim) or a Chacham's daughter to an ignoramus.

(R. Yochanan): Marriage of a Bas Kohen to a Yisrael will not go well.

Question: What will happen?

Answer #1 (Rav Chisda): She will be widowed, divorced, or will not have children (these are the three outcomes the Torah discusses for such a marriage).

Answer #2 (Beraisa): She will bury him [prematurely], or vice-versa, or she will lead him to poverty.

Question: But R. Yochanan said that one who wants to get rich should cling to the seed of Aharon - all the more so Torah [if he is a Chacham] and Kehunah will make one rich!

Answer: It is good for a Bas Kohen to marry a Chacham Yisrael, but not an ignoramus.

R. Yehoshua married a Bas Kohen and fell sick - he understood that he was punished because he was unworthy to marry the seed of Aharon.

Rav Idi bar Avin married a Bas Kohen and had two sons that were authorized to give Halachic rulings, Rav Sheshes and R. Yehoshua brei d'Rav Idi.

Rav Papa: Had I not married a Bas Kohen, I would not have become rich.

Rav Kahana: Had I not married a Bas Kohen, I would not have been exiled (Maharsha - out of humility, he did not consider himself to be a Chacham).

His Talmidim: But you were exiled to a place of Torah (Eretz Yisrael - this was beneficial)!

Rav Kahana: I was not exiled [to a place of Torah] like people normally are (willingly - he fled the kingdom).

(R. Yitzchak): Anyone who benefits from a meal of Reshus will ultimately be exiled - it says [about people who indulge in physical pleasures] "V'Ochlim Karim mi'Tzon...; Lachen Atoh Yiglu b'Rosh Golim."

(Beraisa): If a Chacham eats excessively, he will ultimately destroy his house, widow his wife (Rashi - he will abandon her to pursue income, making her like a widow), orphan his children, forget his learning, and have many arguments (because he forgot his learning; alternatively, with creditors);

His words are not heeded; he desecrates Hash-m's name, his Rebbi's name and his father's name; and he gives a bad repute to himself and his descendants for all generations.

Question: What is the bad repute?

Answer #1 (Abaye): They call him [or them] 'the one (Maharsha; Rashi - the son of the one) who [constantly] heats the oven [for his own consumption]'.

Answer #2 (Rava): They call him 'the one who dances in the pub [so people will give drinks to him]'.

Answer #3 (Rav Papa): They call him 'the one who licks (finishes all the food in serving) bowls'.

Answer #4 (Rav Shemayah): They call him 'the one who folds his garment and crouches [to sleep, for he is too drunk to walk home]'.

(Beraisa): One should sell all his property [if necessary] in order to marry a Chacham's daughter - even if he will die or be exiled, his children will [learn from her and] be Chachamim.

One should not marry the daughter of an Am ha'Aretz (here, this refers to an ignoramus) - if he will die or be exiled [from his house], his children will be Amei ha'Aretz.

(Beraisa): One should sell all his property in order to marry a Bas Chacham and to marry his daughter to a Chacham;

This is like [planting pits of] grapes of a vine with grapes of a vine - it is a nice match and yields proper progeny;

One should not marry a Bas Am ha'Aretz - this is like grapes of a vine with grapes of a shrub - it is repulsive and does not yield proper progeny (it is like Kil'ayim - Iyun Yakov).

(Beraisa): One should sell all his property in order to marry a Bas Chacham;

If he cannot, the order or preference for the girl's father is as follows - a great Tzadik; a head of the congregation; a treasurer of Tzedakah; a Rebbi of children;

He should not marry a Bas Am ha'Aretz, for an Am ha'Aretz is Sheketz and his wife is Sheretz (Rashi - not careful about Mitzvos; ha'Rif - issue of something Tamei is Tamei); regarding their daughters it says "Arur Shochev Im Kol Behemah" (they lack understanding; like animals).

(Beraisa - Rebbi): An Am ha'Aretz may not eat meat (Maharsha - because it has many prohibitions one must be careful about - slaughter, meat and milk...)

It says "Zos Toras ha'Behemah veha'Of" - only one who engages in Torah may eat meat of animals and fowl.

(R. Elazar): One may Nocher (tear the windpipe and esophagus) an Am ha'Aretz, even on Yom Kipur that is on Shabbos. (Tosfos - he intentionally angers Hash-m - he is prone to kill others; Maharsha - one may shame him, which is likened to murder, even on a day of Shalom amidst Yisrael; Ya'avetz, citing Sefer Chasidim - if he is pursing someone to kill him, anyone may kill him, even if he could be stopped by wounding him.)

Talmidim: Why don't you say that one may slaughter him?

Answer: One blesses on slaughter [of animals], but not on killing an Am ha'Aretz.

(R. Elazar): One may not accompany an Am ha'Aretz on the road - "Ki Hu Chayecha v'Orech Yomecha" - if he is not concerned for his own life (he does not learn), all the more so he is not concerned for another's life!

(R. Shmuel bar Nachmani): One may tear an Am ha'Aretz like a fish.

(R. Shmuel bar Yitzchak): He tears him from the back [to kill him immediately].

(Beraisa - R. Akiva): When I was an Am ha'Aretz, I used to say 'if you give me a Chacham, I will bite him like a donkey!'

His Talmidim: You should have said 'like a dog' (it is more wont to bite)!

R. Akiva: A dog bites but does not break bones - a donkey bites and breaks bones.

(Beraisa - R. Meir): Marrying one's daughter to an ignoramus is like tying her up in front of a lion:

Just like a lion tramples and eats [without waiting for his prey to die] without shame, an Am ha'Aretz hits his wife and has relations [without waiting for her to consent] without shame.

(Beraisa - R. Eliezer): If Amei ha'Aretz did not need the business of Chachamim, they would kill us!

(Beraisa - R. Chiya): Learning Torah in front of an Am ha'Aretz is [shameful to him] like having relations with the latter's betrothed in front of him - "Torah Tzivah Lanu Moshe Morashah Kehilas Yakov" - we read this it is as if said Me'orasah (engaged, to all Yisraelim).

Amei ha'Aretz hate Chachamim more than Nochrim hate Yisrael; their wives hate Chachamim even more (Pesach Einayim - because Chachamim's wives do not lend Kelim to them and distance themselves from them at a time when there is Taharah).

(Beraisa): A Chacham who ceased to learn hates Chachamim even more than wives of Amei ha'Aretz (he knows how much Chachamim despise him).

(Beraisa): Six laws were taught regarding an Am ha'Aretz:

We do not give testimony in front of him (Me'iri - with two other judges - we need not say that we do not summons him to be a witness, this follows from the next law), and we do not accept testimony from him;

We do not reveal secrets to him, we do not make him an overseer over orphans, or over Tzedakah, and one may not accompany him on the road.

Some add, if we find something which was surely lost by an Am ha'Aretz (it is clear from the object or location), we do not announce it [to return it].

The first Tana holds that we return it - perhaps he will have worthy children that will benefit from it - "Yachin v'Tzadik Yilbash."

(Mishnah): Similarly, if one left [Yerushalayim... R. Meir requires one to return for a k'Beitzah of Kodshim or Chametz; R. Yehudah says, for a k'Zayis].

Inference: R. Meir holds that k'Beitzah is an important amount, and R. Yehudah holds that even k'Zayis is important.

Contradiction: Elsewhere, they hold the opposite!

(Mishnah) Question: How much must one eat to be included in a Zimun (a responsive invitation to bless after eating)?

Answer #1: He must eat at least a k'Zayis (we assume that the anonymous first Tana is R. Meir);

Answer #2 (R. Yehudah): He must eat at least a k'Beitzah.

Resolution #1 (R. Yochanan): The opinions must be switched (in the other Mishnah - Tosfos Berachos 49B (R. Meir)).

Answer #2 (Abaye): We need not switch the opinions:- Zimun is learned from verses, Kodshim and Chametz depend on reasoning:

R. Meir expounds "V'Ochalta" refers to eating, which is normally a k'Zayis; "v'Sovata" refers to drinking (mid'Oraisa, one is obligated to bless only if he satisfied his thirst);

R. Yehudah expounds "V'Ochalta v'Sovata" - eating which satiates, i.e. k'Beitzah.

R. Meir holds that the Shi'ur to obligate returning for Kodshim and Chametz equals the Shi'ur for Tum'ah, i.e. k'Beitzah;

R. Yehudah holds that the Shi'ur for returning equals the Shi'ur for Isur, i.e. k'Zayis.

(Beraisa - R. Noson): The Shi'ur for both of these is two k'Beitzim.

Chachamim disagreed.