[bm 43b. We begin five lines from the bottom of 43a. Our mishna had presented Beit Hillel's ruling that a custodian who has misappropriated a deposit pays according to the value of the deposit "when it was taken."]
We learned (in our mishna): Beit Hillel says: (The custodian pays according to) the time it was taken. What does "the time it was taken" mean?
If you say "the time it was taken out of this world" [i.e., when it was destroyed], then how? If it had decreased in value (between the time that it was taken and the time it was destroyed), is there anyone who holds [that the robber should pay the decreased value rather than its original value]? Havn't we learned in a mishna that all robbers pay according to the time of robbery? And if it had increased in value, that is Beit Shammai's position (as well). [Thus, the dispute between Beit Hillel and Beit Shammai about "the time it was taken" can't refer to the time it was destroyed!]
Instead, it obviously must refer to the time it was taken from the owner's possession. [Rashi: The dispute would be in the case of increased value. Beit Shammai would hold the custodian liable for the increased value, but Beit Hillel would hold him liable only for its value at the time of robbery.]
[The gemara objects to this analysis:] Does that mean that Rabbah/Rava? [who, in our previous installment, ruled that if the value increased, the robber pays the increased value] rules according to Beit Shammai? [This is inconceivable; in disputes between Beit Shammai and Beit Hillel, the halakha almost always follows Beit Hillel.]
[The gemara now backtracks to its initial proposal, that "time it was taken" means the time it was destroyed.] Rabbah/Rava? would say: When it increases in value, everyone agrees [that the custodian pays the increased value]. When do they disagree? When the value decreases. Beit Shammai says that misappropriation does not depend on loss [i.e., as soon as the custodian took the item, he took on the status of a robber], and when it decreased in value it was in his possession [and he pays the value at the time he took it]. Beit Hillel holds that misappropriation does require loss [so that when the custodian took it, he did not acquire possession], and when it decreased in value it was (still) in the owner's possession. [Thus, the deposit came into the owner's possession only when he destroyed it ... but at that time its value had already decreased, so that the custodian pays only the decreased value.]
[The gemara rejects this analysis too:] But hasn't Rava said that misappropriation does _not_ depend on loss? [See bm41b.1] Are we to say that Rava holds according to Beit Shammai? [Again, this is inconceivable.]
Instead, what are we dealing with? For example, (a custodian) who moved (a deposited barrel to stand on) to reach pigeons. And they (Beit Shammai and Beit Hillel) disagree on borrowing without permission. Beit Shammai says that borrowing without permission is robbery, so when it decreased in value it was in his (the custodian's) possession [and he pays according to its value at the time of borrowing]. Beit Hillel says that borrowing without permission is borrowing, so when it decreased in value it was still in the owner's possession [and the custodian pays according to its value when he destroyed it].
[Again the gemara rejects this possibility:] But Rava said (Bava Batra 88a) that, according to the rabbis, a borrower without permission is a robber; shall we say that Rava rules according to Beit Shammai? [Inconceivable!]
[The gemara presents its final analysis:] Instead, they (Beit Shammai and Beit Hillel) disagree about (material) improvement of the robbed property. [The issue is not change in market value, but actual favorable changes in the deposited item. For example, a sheep might grow more wool, or become pregnant.]
Beit Shammai says that material improvements (accrued during the period that it was in the hands of the robber) belong to the owner. Beit Hillel says that (such) material improvements belong to the robber.
And this is a tannaitic dispute, as we learned in a b'raita: If someone acquired a ewe by robbery and sheared it, or it gave birth, he pays for it, and for its wool and for its offspring; these are the words of R. Meir. R. Yehuda says: it goes back as it is [i.e., the robber returns the ewe but keeps the wool and offspring]. [Thus, Beit Hillel in our mishna holds like R. Yehuda, and Beit Shammai holds like R. Meir. We might note that R. Yehuda's opinioins have priority over those of R. Meir (Eruvin 46b).]
And we can see this as well in a careful reading of our mishna: Beit Shammai says he suffers the increase or the decrease, but Beit Hillel says (he pays) according to the time it was taken." [Rashi: the mishna used the terms "increased" and "decreased" rather than "appreciated" or "depreciated.]
[The gemara finally accepts this:] We can indeed learn this [i.e., this analysis is correct].
[Our mishna had presented the ruling of of Beit Shammai [the custodian pays according to the value of the deposit at the time of misappropriation or destruction, whichever is greater], Beit Hillel [the custodian pays according to the value of the deposit at the time of its physical destruction], and R. Akiva [he pays the value at the time the claim was made.
After considerable discussion, the gemara concluded that there is no dispute in the case of the deposit's appreciation or depreciation. According to all opinions, the onus is on the robber. Rather, the difference of opinion refers to the case in which the deposited item has materially improved during the period between the misappropriation and its destruction. Beit Shammai awards the improvement to the original owner; Beit Hillel awards it to the robber.]
[The gemara now takes up the opinion of R. Akiva, who disagrees with both Beit Shammai and Beit Hillel.] [Citing our mishna:] R. Akiva said: according to the time of the claim.
Rav Yehuda said in the name of Shmuel: The halakha is like (the opinion of) R. Akiva.
And R. Akiva concedes that when there are witnesses [Rashi: who saw the misappropriation, and who can testify to the deposit's value at that time, that the custodian pays the value at the time of misappropriation.] Why? The Torah says (Lev 5:24) "To whom it belongs he will give it at the day of his guilt" [implying that he pays the value on "the day of his guilt]. But since there are witnesses, it is from that moment that he aquires guilt.
R. Oshaya said to Rav Yehuda: My teacher -- is that what you say?! But R. Asi said to R. Yohanan: R. Akiva disagrees with his colleagues even (in the case that) there are witnesses. Why? The Torah says (Lev 5:24) "To whom it belongs he will give it at the day of his guilt," and it is the court [not the witnesses] that establish his guilt.
R. Zeira said to R. Abba bar Pappa: When you go there [from Babylonia to Israel], take a detour to the ascent of Mount Tzur and visit R. Yaakov bar Idi and ask him if he heard from R. Yohanan whether the halakha is according to R. Akiva or not. He said to him [R. Yaakov bar Idi said to R. Abba bar Pappa]: This is what R. Yohanan said: The halakha is always according to R. Akiva.
[The gemara asks:] Always? Rav Ashi said: You should not say that this ruling [by R. Akiva] applies (only) where there are no witnesses, but not where there are witnesses. [In other words, "always" mean whether or not there are witnesses, the halakha is like R. Akiva.]
Or perhaps also, ["always" means that the halakha is like R. Akiva even] if he (the custodian) returned it to its place and it broke [afterwards, by accident rather than by negligence], to distinguish it from the position of R. Yishmael, who said that we do not need the owner's awareness [of the item's return to protect the custodian from liability]. R. Yohanan is telling us that the owner's awareness (that the item has been returned) _is_ required (in order to free the custodian of liability). [For the discussion of whether or not the owner's knowledge is required, see bm40b.]
Rava said: The halakha is according to Beit Hillel. [Thus, despite R. Yohanan's "always", Rava overrules R. Akiva's opinion in the present case, and - since Rava is a "later sage" - his ruling is halakhah.]
[We end at the mishna at the bottom of 43b.]