If there was a pile of Chametz, and a weasel took a piece and entered one of two checked houses, and we do not know which it entered, this is like the case of two paths:

(Mishnah - R. Yehudah): If Reuven and Shimon walked on two different paths; one of which is Tamei (there is Tum'as Mes underneath which is Metamei one who traverses it) and the other is Tahor, and we do not know which is Tamei, and they touched Taharos:

If they ask [about the Taharos] separately, we tell each of them that his Taharos are Tehorim (Safek Tum'ah in Reshus ha'Rabim is Tahor); if they ask together, we are Metamei the Taharos of both of them (we cannot Metaher both, for this cannot be; there is no logic to Metaher one and Metamei the other);

R. Yosi says, in either case both Taharos are Temei'im.

(Rava or R. Yochanan): If they ask at the same time, all agree that we Metamei both; if they ask at different times, all agree that we Metaher both;

They argue about when one comes to ask for himself and his friend - R. Yehudah compares this to asking at different times; R. Yosi compares this to asking at the same time. (Likewise, if the owners of the houses ask together, both must check; if they ask separately, both are exempt; Tana'im argue about when one asks for both of them.)

If a weasel took Chametz and we are unsure whether or not he entered a checked house, this is like the argument of R. Eliezer and Chachamim regarding a valley:

(Mishnah - R. Eliezer): If there was Tum'ah in a certain field in a valley, and one entered the valley in winter (few people go there then, it is considered Reshus ha'Yachid regarding Tum'ah) but does not know whether he entered that field, he is Tahor;

R. Elazar is Metaher Safek Bi'ah (we are unsure whether he even entered the place of Tum'ah - see note 11 in Appendix), but he is Metamei Safek Negi'ah (we are unsure whether or not he touched Tum'ah).

Chachamim Metamei [even a double Safek. Rashi - regarding Bedikah mid'Rabanan, all are lenient. Ba'al ha'Ma'or - even Bitul is not required - we are stringent about a double Safek only regarding Tum'ah.]

If a weasel took Chametz into a house and we checked and did not find Chametz, this is like the argument of R. Meir and Chachamim:

(Mishnah): [If a heap containing Tum'as Mes became confused with two Tahor heaps, and one or two were checked and found to be Tehorim, [it or] they are Tehorim, the other[s] are Teme'im;

If all three were checked and found to be Tehorim,] R. Meir [is Metamei all of them, for he] say that anything Muchzak to be Tamei keeps its Chazakah until we know where the Tum'ah went;

Chachamim say, one digs until he finds a big rock or virgin soil (we are not concerned for Tum'ah underneath it. Tosfos - they argue similarly about a mid'Oraisa Safek about Chametz, i.e. if Bitul was not done - but after Bitul Bedikah is a Safek mid'Rabanan, all are lenient.)

If a weasel took Chametz into a house and we checked and found Chametz, this is like the argument of Rebbi and R. Shimon ben Gamliel:

(Beraisa - Rebbi): If a grave was lost in a field, one who enters the field is Tamei;

If a grave was found in the field, one who enters[elsewhere in] the field is Tahor - we assume that it is the same one that was lost.

R. Shimon ben Gamliel says, the entire field must be checked (if not, one who enters is Tamei. Ba'al ha'Ma'or - in this and the coming cases, they argue similarly about Bitul, but all exempt from Bedikah mid'Rabanan; Ra'avad - the rule of Safek mid'Rabanan l'Kula does not apply to Bedikah, since it was enacted on account of Safek.)

If one left nine pieces of Chametz and later found 10, this is like the argument of Rebbi and Chachamim:

(Beraisa - Rebbi): If one left 100 Zuz [of Ma'aser Sheni] and later found 200, we consider it a mixture of Chulin and Ma'aser;

Chachamim say, it is all Chulin (we assume that the original money was taken and this is new money. Rashi - they argue similarly regarding Chametz - Chachamim assume that these are 10 new pieces and require Bedikah for the nine; the same applies to the coming case.)

If one left 10 pieces ofChametz and later found nine, this is like the Seifa:

(Beraisa - Rebbi): If one left 200 Zuz [of Ma'aser] and later found 100, it is from the initial money, and the other 100 was taken;

Chachamim say, it is all Chulin.

If one left Chametz in one corner and later found it in another corner, this is like the argument of R. Shimon ben Gamliel and Chachamim:

(Beraisa): If an axe was lost in a house, [every Keli in] the house is Tamei - we [are stringent to] assume that the person who entered and took it was Tamei [and he touched other Kelim, too];

R. Shimon ben Gamliel is Metaher - we assume that the owner forgot that he lent it to someone else or that he moved it from corner to corner.

Question: The first Tana does not discuss when it was found in a corner!

Answer: The Beraisa is abbreviated, it means as follows - if an axe was lost in a house, the house is Tamei - we assume that a Tamei person entered and took it;

If he left in one corner and found it in another, the house is Tamei - we assume that a Tamei person moved it;

R. Shimon ben Gamliel is Metaher - we assume that the owner forgot that he lent it to someone else or that he moved it from corner to corner. (Regarding Chametz, Chachamim assume that a mouse took it, and perhaps different Chametz is in the other corner, so the house must be checked; R. Shimon ben Gamliel exempts - we assume that the owner forgot that he himself moved it.)

(Rava): If a mouse entered a house with a loaf in its mouth and [later] crumbs were found, the house must be checked, for mice normally do not crumble bread (presumably, the loaf is elsewhere);

If a child entered a house with a loaf and crumbs were found, the house need not be checked, for children often crumble bread (presumably, these crumbs are the remains of the loaf).

Question #1 (Rava): If a mouse entered [a checked house] with a loaf and a mouse left with a loaf, what is the law?

Do we assume that it is the same [mouse and loaf, hence another Bedikah is not needed], or not?

Question #2 (Rava): If you will say that we assume that it is the same - if a white mouse entered with a loaf and a black mouse left with a loaf, what is the law?

We know that it is a different mouse [and presumably, a different loaf];

Or, perhaps the latter mouse cast it from the first and took it!

Question #3 (Rava): If you will say that mice do not take from each other - if a mouse entered with a loaf and a weasel left with a loaf, what is the law?

Surely, the weasel took it from the mouse;

Or, perhaps it is a different loaf - had it taken it from the mouse, the mouse would be in its mouth!

Question #4 (Rava): If you will say that had it taken it from the mouse, the mouse would be in its mouth - if the weasel left with a mouse and a loaf in its mouth, what is the law?

Surely, it is the same loaf;

Or, perhaps it is a different loaf - if it was the same, it would be in the mouse's mouth!

Or, perhaps [it really is the same -] the mouse was afraid and dropped it, and the weasel took it.

These questions are not resolved.

Question #1 (Rava): If a loaf is on the ceiling rafters, must one bring a ladder to get it down, or not?

Do we say that Chachamim did not exert someone so much - since [normally] it will not fall by itself, we are not concerned lest he eat it;

Or, since it could fall by itself, we are concerned lest he eat it!

Question #2 (Rava): If you will say that we are concerned lest it fall by itself - if a loaf is in a pit, must one bring a ladder to bring it up, or not?

Since it cannot come up by itself, we are not concerned;

Or, perhaps he will descend to do his needs in the pit and will [forget and] eat it!

Question #3 (Rava): [If you will say that perhaps he will descend for his needs and eat it -] if a loaf is in a snake's mouth, must one bring a snake charmer to remove it, or not? (Rashi deletes this from the text the bracketed words - he holds that this is an independent question.)

Perhaps Chachamim make a person exert himself, but they do not require him to spend money [for things he himself cannot do] - or perhaps he must even spend money!

These questions are not resolved.

(Mishnah - R. Yehudah): We check on the night of (before) the 14th, on the morning of the 14th, and at the time of Bi'ur (six hours of the day);

Chachamim say, if someone did not check on the night of the 14th, he checks on the morning of the 14th; if he did not check [at either time] on the 14th, he checks during the festival; if he did not check during the festival; he checks after the festival.

What one leaves over [to eat before Bi'ur] should be put in a covert place, so he will not need to check for it.

(Gemara) Question: What is R. Yehudah's reason [to require three Bedikos]?

Answer (Rav Chisda and Rabah bar Rav Huna): The three times of Bi'ur correspond to the three times the Torah commands to get rid of Chametz "V'Lo Yera'eh Lecha Chametz v'Lo Yera'eh Lecha Se'or," "Shiv'as Yomim Se'or Lo Yimatzei b'Vateichem," and "Ach ba'Yom ha'Rishon Tashbisu Se'or mi'Bateichem."

Version #1 - Question (Rav Yosef - Beraisa - R. Yehudah): If someone did not check at [one of] these three times, he does not check later.

This shows that they argue only about whether or not one checks after [the third time - but even R. Yehudah require only one Bedikah]!

Version #2 - Rav Masnah - Question (Rav Yosef - Beraisa - R. Yehudah): If someone did not check at one of these three times, he does not check later. (In this version, the Beraisa explicitly says that R. Yehudah requires only one Bedikah.)

This shows that they argue only about whether or not one checks afterwards. (end of Version #2)

Answer: R. Yehudah agrees that only one Bedikah is needed - they argue about whether or not we check after Chametz is forbidden:

R. Yehudah decrees not to check after it is forbidden, lest one find Chametz and eat it; Chachamim do not decree.