The second perek of Massekhet Shekalim opens with a discussion of how the shekalim are delivered to the Temple. The Mishna on our daf clarifies that there was no obligation for every individual to bring half-shekel coins to the Beit haMikdash, rather they could be collected in every community, exchanged for larger coins and sent with a messenger to Jerusalem.
What if the money was lost or stolen en route to the Temple? The Mishna teaches that responsibility for lost or stolen money depends on when the money disappeared.
With regard to the residents of a town who sent their shekels to the Temple and they were stolen from the agent on the way or were lost, if the collection of the chamber had already been collected before these shekels arrived, the agents must take the oath of a bailee to the treasurers [gizbarin]. After the collection of the chamber, all the shekels that have been contributed become the property of the Temple, so the Temple treasurers who are in charge of this property become the opposing litigants of the agents. If the ceremony has not yet been performed and the contributions have not yet been collected into the baskets, the shekels are considered the property of the residents of the town, and therefore the agents must take an oath to absolve themselves to the residents of the town. Since those shekels are still considered the property of the residents of the town because the shekels never reached the Temple, they have not fulfilled their obligation. Therefore, the residents of the town must contribute other shekels in their place.
In order for the communal sacrifices that were brought in the Temple to be considered to have come from the entire nation, even before the half-shekel donations arrived in the Mikdash, money was set aside on Rosh Hodesh Nisan for the purchase of sacrifices. This money – called terumat ha-lishkah – was, in essence, a loan that was to be repaid when the half-shekalim arrived, as can be seen from the above Mishna.
One of the concerns of the Gemara is whether the messenger in the story is paid (a shomer sakhar) or a volunteer (a shomer hinam). The law of shomer sakhar, as described in the Torah (Shemot 22:9-12), understands that in exchange for payment the guard accepts a high level of responsibility for the object he is watching. In such a case he will have to replace the object if it was lost or stolen. A shomer hinam, on the other hand (see Shemot 22:6-8) can swear that he did not act irresponsibly and will not be responsible for it.
Although at first glace it appears that the case of our Mishna must be talking about a shomer hinam, who can swear and be free of any responsibility, the Gemara on our daf concludes that it could also be discussing the case of a shomer sakhar who can, in this case, swear that money had been lost or stolen because it was “lost” when the boat he was on sank or “stolen” by armed robbers. These cases are considered circumstances beyond the control of the guard, who is, therefore, not held responsible for the loss on any level.