Explanation #3 (Ri): We learned that a valley is Reshus ha'Rabim for Tum'ah only if winter did not pass over it, i.e. over the Tum'ah that became known. Winter did not pass over from when he passed through, and he does not know whether he entered in summer or winter;

If he comes to ask in front of us, we should consider it Reshus ha'Rabim, for we follow the current time;

However, if winter passed over it, i.e. he did not find out whether he entered in summer or winter, and from when the Safek came winter passed over. Even if he comes to ask in summer, it is Reshus ha'Yachid for Tum'ah.

We should not follow the current time, since winter was closer.

Explanation #3 (cont.): "It is Reshus ha'Yachid for this and for this" means regarding Tum'ah, just like regarding Shabbos.

Support: Now it is fine that we bring here this matter, whether we follow the current time, which this Sugya discusses.

Explanation (Rashbam): Both according to R. Meir and Rabanan, [the Gemara] asks what proof [the recipient] must bring.

Rejection: Obviously, according to R. Meir he must bring a proof through witnesses! Also below, the Rashbam explained that R. Meir requires a proof through witnesses.

Question: Why does Rabah establish our Mishnah to discuss a proof through witnesses? He establishes Rabanan like R. Yakov, and R. Meir like R. Nasan;

Rabah himself holds like R. Nasan. He should establish [our Mishnah to discuss] validation of documents, and all hold like R. Nasan!

Answer #1: If we find in any place that [Rabah] holds that one who admits that he wrote (authorized) a document, [the bearer, i.e. the lender] need not validate it, this would be fine. Also if we would establish their argument regarding validation of documents, Rabanan would not hold like him.

Answer #2: It connotes to him that Rabanan's proof is like R. Meir's proof, i.e. through witnesses.

Question: According to the Havah Amina that the buyers were [interested in] checking him, whether or not he was an adult, how could it be that he appeared a minor in his lifetime, and he appears an adult after death?

Answer #1 (R. Tam): In his lifetime there were white hairs, and they were Shuma (not a Siman of adulthood), and now they blackened after death, and look like Simanim.

Rebuttal: We do not find anywhere regarding hairs being a Siman, a distinction between white and black! (Ramban - R. Tam learns from "until the black becomes the majority over the white" - Kesuvos 36a.)

Answer #2 (Ri): Perhaps in his lifetime there were no pores, and due to death there are pores, like we say in Nidah (52a) that pores, even though there are no hairs, are a Siman. (This Dibur continues on Amud B.)

Question: Why should we say that he was a minor, since he reached his years? We say in Nidah (48a) that a minor girl who reached her years, she need not be checked, for there is a Chazakah that she brought Simanim!

Answer: After he was an adult, i.e. he reached his years, he did not have Simanim of adulthood, therefore there is a Safek perhaps he was still a minor.

Explanation: Presumably, since he truly sold, they would find witnesses to validate their document;

Rather, this teaches that they needed to seek witnesses that he was an adult at the time of the sale, and like Rabanan, who say ha'Motzi me'Chavero Alav ha'Re'ayah.

Question: What was the difficulty? Rabanan said [he must bring] a proof through Kiyum of the document only because they hold like R. Nasan, who says that we follow the current state. If he is healthy now, we should say that then he was healthy. However, here no Chazakah applies!

Answer: We can say that the Chazakah that witnesses sign a document only if adults did it helps like the Chazakah that we follow the current state.

Explanation: The heirs wanted to take [the property] from [the buyer's] hands, and wanted to check if he is a minor.

Support: Now it is fine that [R. Akiva] told them that Simanim are prone to change after death. Even if you will not find Simanim, we can say that [the hairs] fell out after death.

Distinction: However, heirs are not allowed to disgrace him due to inheritance, for they did not give anything. Also, he is their relative.

Reference: Above (48b) I brought this matter regarding "our words were Moda'ah. (Rav Nachman holds that all Tana'im agree that witnesses are not believed to say that the document was Amanah or there was a Moda'a.)

Explanation: [They properly protested] due to the reason of Kiyum, but not due to the reason of witnesses [that he was an adult].

Implied question: Above, Reish Lakish challenged R. Yochanan from Bar Kapara's [version of the] Mishnah, and R. Yochanan said "I say that that if one admits that he wrote a document, [the bearer] need not validate it"!

Answer: [Now we hold that] he never said so. The entire Sugya above is not true according to this conclusion.

Support: We find like this in Yevamos (35b). R. Yochanan challenged Reish Lakish, and in the conclusion, we establish their argument about another matter, regarding one who does Chalitzah to a pregnant woman.

We find like this also in Chagigah (7a) regarding the Aron, and in Nidah (24a) regarding the face of a baby that was mashed.

Implied question: Above, R. Yochanan said to R. Yanai "doesn't our Mishnah teach this?!"

Answer: He did not ask from Rabanan's opinion, just he mentioned to him the Mishnah of the argument of Rabanan and R. Meir about this matter. (See also Tosfos Bechoros 4b.)