bm43a: We begin with the mishna at the top of the page. Some points to remember: An unpaid custodian is not liable for loss. A paid custodian is liable for loss and theft but not for unavoidable loss. A borrower is liable even for unavoidable loss.]
Mishna: One who deposits money with a moneychanger: If it (the money) was bundled, he (the moneychanger) cannot use it; therefore [since he is an unpaid custodian], he is not liable if it is lost. If (the money) was loose, he can use it; therefore [since the moneychanger can be regarded as either a paid custodian or as a borrower], if it is lost, he is liable. [The Hebrew for moneychanger is "shulkhani," derived from "shulkhan," a table. The English "banker" is, of course, etymologically derived from "banco," or bench!]
(If the money was deposited) with a private householder, whether it is bundled or loose, he cannot use it; therefore he is not liable if it is lost.
A storekeeper is like a private householder; these are the words of R. Meir. R. Yehuda says: A storekeeper is like a moneychanger.
Gemara: He (the moneychanger) cannot use the money because it is bundled?! [Why should bundling the money make a difference?]
Rav Assi said in the name of Rav Yehuda [a Babylonian amora of the second generation, not the tanna R. Yehuda in the mishna]: If it was bundled and sealed [clearly indicating that the owner did not want the moneychanger to use the deposited money].
Rav Mari said: If it was bundled with an unusual knot. Others say that Rav Mari asked about the law in the case of an unusual knot. [The gemara answers regarding the unusual knot:] Let it stand [i.e., there is no definitive ruling].
[The mishna said:] If it is loose he (the moneychanger) may use it [but is liable for loss]. Rav Huna said: (he is liable) even if it was lost through an unavoidable accident. But the mishna said "lost" (and did not use the term "unavoidable")? [Rav Huna thus regards the moneychanger as a borrower, wheras - on the face of it - the mishna regards him as a paid custodian.]
[The gemara answers:] It is consistent with Rabba, for, as Rabba said: "They were stolen" refers to an armed bandit; "they were lost" refers to when his ship sank at sea. [Thus, Rabba interpreted the term "lost" to refer even to inavoidable loss. Rabba's interpretation came up back in Chapter 2 (bm29a.1).]
Rav Nachman said: If the loss was unavoidable, he (the moneychanger) is not liable. [Rashi: As long as he didn't use the money, he is a paid custodian, and not liable for unavoidable loss.]
Rava said to Rav Nachman: According to you -- who holds that he is not liable if the money was lost through an unavoidable event -- he is apparently not a borrower. But if he is not a borrower, he is not a paid custodian either [since he never gained any profit, and -- like an unpaid custodian -- he should not be liable for _any_ loss].
Rav Nachman said to him: I admit [Rashi: that he is a paid custodian]. Since he benefits from the money, he must give benefit to the owner [in the case of loss]. The benefit he receives is that if a profitable purchase becomes available, he can take advantage of it [using the deposited money]; he is therefore a paid custodian. [Rav Nachman's position is that the benefit of having the money available is enough to make him a paid custodian. As soon as he actually uses the money, he takes on the status of a borrower, with even greater liabilty.]
[Rav Huna had said that the moneychanger was liable even for unavoidable loss.] Rav Nachman challenged Rav Huna (on the basis of a mishna [Me'ilah 21b]). [Money or property belonging to the Temple cannot be used for private profit; doing so is me'ilah (simony).] [The mishna in Me'ilah:] If one [presumably a treasurer of the Temple] deposited Temple money (inadvertently) with a moneychanger: If it was bundled, he (the moneychanger) cannot use it; therefore, if he (the moneychanger) spent it, he (the treasurer) is not guilty of me'ilah. But if it (the money) was loose, he (the moneychanger) can use it, and if he spent it, he (the treasurer) is guilty of me'ilah.
[Rav Nachman now makes his point:] If you say that the moneychanger is liable for unavoidable loss [Rav Huna's position above], why does the mishna specify "if he spent it?" Even if he did not spend it [the treasurer should be liable]! [Rav Huna's position that the moneychanger is liable for unavoidable loss seems to derive from the fact that as soon as he receives the money, he becomes a borrower. If that is the case, the treasurer should be liable as soon as the money is transferred to the moneychanger, for at that moment the money is transferred from the Temple to the moneychanger as a loan.]
He (Rav Huna) said to him (Rav Nachman): That is the law [i.e., the treasurer _is_ liable] even if the moneychanger did not spend the money. But since the first part of the mishna [dealing with bundled money that the moneychanger cannot spend] specified "spent" [to show that the treasurer is not guilty if the moneychanger misappropriated the deposit], the latter clause of the mishna also specified "spent."
[Although Rav Huna would seem to have had the last word, halakhah follows Rav Nachman.]
Mishna: A custodian who misappropriated a deposit: Beit Shammai says he (the custodian) suffers for its increase or decrease (in value).
[If it increased in value, he must pay the increased value. If it decreased in value, he must pay the original value. Rashi reminds us that a custodian who misappropriates a deposit has the status of a robber. If the deposit is still intact, he must return it, but if it was destroyed after the misappropriation, he must pay either the value at the time of misappropriation or the current value, whichever is greater.]
But Beit Hillel says that he pays according to (its value at) the time of its removal. R. Akiva says: according to (its value at) the time of the claim [Rashi: when he is brought to court; the gemara will explain these two positions].
Gemara: Rabbah [emended to Rava] said: One who robbed a keg of wine that was originally worth a zuz and is now worth four zuzim: If he broke it [the keg] or drank it [the wine], he pays four zuzim; if it broke incidentally [i.e., accidentally], he pays a zuz [its value at the time of the robbery].
What is the rationale? If it had remained intact [when the robber was ordered by the court to return it], it would have been returned intact to its owner. Now that he broke it or drank it, he has effectively robbed it, and we learned in a mishna [Bava Kamma 93b] that all robbers pay according to the time of the robbery [which now has been shifted from the time of the original robbery to the time when he broke the keg or drank the wine].
If it broke incidentally, he pays only a zuz. Why? Mow (at the time that it broke), he didn't do anything at all -- why should he be liable? He had become liable when he robbed the keg, which at the time was worth only a zuz [and did not incur any further liability when it broke].
[We end four lines from the bottom of 43a.]