Explanation: This is like Rebbi, who says in Bava Kama (114a) that the owner despairs when something was taken by a Stam Ganav or Gazlan (covert thief or open robber).

Version #1: The text says "if the owner despaired, they are his (the finder's). We must say that the case is, he can save easily if he pursues at the time [that the river] overflows they are washed away;

If not, this is like a high tide. It is lost from him and from everyone. Regarding this, we would not say "Stam, no (he does not despair)";

Rather, the case is, he can save easily at the time of overflow, and even if there is no Siman, for rocks or stagnant places in the river will detain them, and he will take them.

And even if others will come first and take them, they will return them to him, for it is recognized that he is the owner, since he pursued immediately.

One might have thought that the case is, if the owner did not pursue immediately at the time of overflow, afterwards he cannot save at all;

The Seifa proves like this, for others will take them when rocks or stagnant places will detain them, and the finders will not return them, for there is no Siman in them.

Explanation: It means as follows. If the owner despaired, i.e. he was there at the time of overflow, and he did not pursue...

Even if he says that he does not despair, his words have no effect. Surely he despairs in his heart!

Stam, when the owner was not there at the time of overflow, and he did not despair until he knew that the river washed it away, and then he cannot save. [He despairs because] he does not have a Siman in them, no (the finder may not keep it).

This is because when he found them, they came to his hand b'Isur , for the owner did not yet know about the overflow. This shows that Yi'ush she'Lo mi'Da'as is not Yi'ush!

Explanation (cont.): The Gemara answers that [the case is,] he could save even after the overflow, e.g. there is a Siman on the Aveidah, so the owner does not despair when he finds out.

The Gemara asks "if so, [what will you] say [to explain] the Seifa? If the owner was pursuing..."

Why must we say that he was pursuing? Even if the owner was there at the time of overflow, and did not pursue, he must return it!

The Gemara answers that he could save even after the overflow with difficulty. Even though there is a Siman on it, he could save [only] through toil, for it will go very far, for the river takes it far away;

Therefore, if [the owner] was there at the time of overflow, and did not pursue, surely he despairs, for now he could save without difficulty, and he does not save.

Distinction: However, if he was not there at the time of overflow, he returns, for when the owner finds out, he will not despair, and he will save with difficulty.

Question: What is the source of this, that Stam he must return? Perhaps "he despaired" comes to exclude if [the owner] was there and pursued. Then, he must return!

Answer: If so, it should not teach "if he despaired." Rather, it should teach Stam "if a river washed away his beams, wood and rocks, they belong to [the finder]";

It is obvious that we do not discuss when [the owner] pursued at the time it overflowed, for the Seifa teaches "if the owner pursued, he must [return]!

Question: We could infer from the Seifa! [He must return] because [the owner] pursues, but Stam, the finder keeps it.

Answer: Really, I can say that the same applies to Stam, he must return. It mentions pursuing only to exclude when the owner was there at the time it overflowed, and did not pursue;

Through the Seifa, we know that we discuss when he cannot save.

Version #2: Rashi's text says "because the owner despaired."

Question #1: The words connote that it is obvious he despaired. If so, from the Reisha itself we can prove that we discuss when he cannot save. There was no need to bring the Seifa!

Question #2: What is the source that Stam, no (he may not keep it)? We can discuss even Stam!

The text: The text says "presumably this is correct, for if he did not make him a Shali'ach [he could not take Terumah]." It does not say "is this reasonable"?!

Explanation: Presumably, also from the beginning he intended for this [to separate high quality Terumah].

Question: We should say that now surely he is pleased with nice Peros, but initially, at the time [the Shali'ach] separated, had he known, he would not have been pleased, for it is not normal to separate high quality Terumah!

This is like we said above (21b) regarding a matter with a Siman. Even according to Rava, one must announce it. Even though he despairs now, this has no effect! (Likewise, his current satisfaction does not help, for initially he was not pleased!)

Answer: Here is different. Since we see that now he is pleased, we say that also initially he was pleased, due to the Mitzvah.

Question: In Kesuvos (99b), we say that a Stam Ba'al ha'Bayis separates one part in 50. If the Shali'ach separated from 10 less or 10 more than this (one part in 40 or 60), it is Terumah, for he can say "I estimated that you intended for this";

Also here, he can say so ["I estimated that you wanted to separate nice Peros"]!

Answer: There, all [of the possibilities] are a Shi'ur of Terumah. Some separate like this (one part in 40), and some separate like this (one in 60). Therefore, since [the owner] did not specify, he can say "I estimated that you wanted to give like this";

However, it is not normal to separate nice Peros. Therefore, he should not have separated from them at all without [the owner's] permission.

Question: Why didn't he eat? Rava said in Bava Kama (119a) that [one may buy Peros from a sharecropper, for] the sharecropper sells from the share he is entitled to!

Answer: There, the sharecropper brought from the house. Presumably, he brings from his share;

However, here he brought from the orchard. Mar Zutra was concerned lest at the time of division he not tell the owner of the orchard "take corresponding to what I gave to them."

Rav Ashi was not concerned for this. Therefore, he ate before Mari bar Isak came, because the sharecropper brings from his share;

Do not say that he relied on [an assumption] that Mari bar Isak will be pleased when he finds out, for the Halachah follows Abaye. Even though now he is pleased, initially he was not pleased.

Explanation: This that we permit when it is lost from him and from all people, you are forced to say that we do not need the verse when he knew and despairs. Even when it is available to all people, it is permitted [for the finder to keep it] through despair;

Rather, we need [the verse] only when he did not know. Even though when he finds out, he will not despair, even if there is a Siman, since it is lost from everyone (the finder keeps it);

Similarly, the case of Isur [to keep it], when it is available to all people, it is forbidden in such a case when we do not know that he despaired, whether or not there is a Siman;

We permit only when he despaired before it came to the finder's hand, [the case in] which the Torah permitted.

Explanation: [We ask that] granted, according to Rava, even though those under the tree or near the tree are forbidden, for their appearance proves about them [that they are from the tree]...

However, dates, which the wind blows far, "their appearance proves about them" does not help. Even if the owner thought that they will fall under the tree, in any case if they would know that the wind will take them far away, they would despair. (Therefore, they are permitted.)

However, according to Abaye, this is Yi'ush she'Lo mi'Da'as (which is not Yi'ush), for the owner thinks that they will fall under the tree, and travelers will not take them, because their appearance proves about them!

Explanation (cont.): We answer that those under the tree are permitted, even according to Abaye, in a place where vermin are common, for he despairs.

Observation: We must say that they often fall, like figs. If not, they would be forbidden according to Abaye, for this is Yi'ush she'Lo mi'Da'as, since he does not expect them to fall, since it is not common for them to fall;

This is like olives and carobs, which are forbidden according to Abaye, since it is not common for them to fall.

Explanation: This is not difficult for Rava, since when [the orphans] mature, they despair, also now it is called despair.

Assertion: Rava knew this Beraisa, like it connotes a little above (21b). It says "regarding a high tide, all agree that it is permitted, like we will say below;

However, he did not infer that the case of Isur is like the case of Heter.

Explanation: [We ask] if there was a fence around the tree, do we permit those that the wind takes over the fence to outside the fence?

The owner thinks that all will fall under the tree, and there they will be guarded from vermin. (Therefore, he does not despair now.)

Explanation #1: [We ask] why must the finder announce it, since the loser has no Siman to give?

We answer that [the finder] announces that the loser should give the Siman of the place it was lost.

Support: Similarly below (28a), it says [that at the end of the festival, in the Mikdash, a finder announces the Aveidah for seven days,] "so that [the loser] will go [back home] in three days, [and if he sees that he lost it] return in three days and he will announce for one day." I.e. the finder announces, and the loser gives a Siman.

Question: In Pesachim (49b), we say that we do not announce the Aveidah of an Am ha'Aretz. [If the finder announces,] how do we know that if it is of an Am ha'Aretz?

Answer: We discuss when he found in a place where Amei ha'Aretz are common.

Explanation #2 (Rashi): The finder announces the place. He says "I found an item in the place Ploni", and [the finder] says "I lost item Ploni", and he takes it.

Question - Citation (below, 28b - Mishnah): If [the loser] says the Aveidah, but he did not give Simanim, his words have no effect.

Inference: Saying the item [that was lost] is not a Siman!

Answer: Also there, it is not because he is suspected to lie, that he lost an item. Rather, [the finder] tells him "just like you lost, we can say that someone else lost [the same kind of item];

However, here we return it, for it is not common that two people lost an item like this in one place.

Observation: According to Rashi, here "he announces the place" is exactly like "he announces the number" above (20b. Even though the Gemara retracted, and said that he announces "documents", the Gemara initially said that he announces the number, just like Rashi says here that he announces the place.)

Explanation: Because Rabah holds that Makom is not a Siman, he needed to say that a Siman prone to be trampled is not a Siman. (The Mishnah obligates announcing bundles of sheaves in a Reshus ha'Yachid. If Makom is not a Siman, they themselves must have a Siman. In a Reshus ha'Rabim, he keeps them! He must hold that a Siman prone to be trampled is not a Siman.)