Bava Metzia - Daf 45
- אסור ללוות דינר בדינר
The Gemara attempts to prove that Rebbe Yochanan is the opinion quoted on the previous Daf that Beis Shammai holds that gold coins are not considered currency at all (and one cannot be mechalel maaser sheni onto them). Rebbe Yochanan said: אסור ללוות דינר בדינר – it is forbidden to borrow a dinar for a dinar (i.e., to repay the same number of dinarim, whose value may be higher at payment, constituting רבית). Since all agree that silver dinarim are currency relative to themselves, he must be discussing gold dinarim, and saying that Beis Shammai considers them like produce (and not currency), even relative to themselves. The Gemara rejects this proof, saying that even if gold is currency relative to itself, such lending is still prohibited. Since gold is considered produce relative to silver (according to Beis Shammai), דאמרינן איהו ניהו דאוקיר וזיל – and we say that [gold] is what appreciates or depreciates relative to silver, payment will appear like ribbis if the gold has a higher value [Tosafos adds that lending silver would have the same issue according to Beis Hillel]. This is supported by Ravin, who quoted Rebbe Yochanan saying that one may be mechalel maaser sheni onto dinarim.
- גזרינן שמא ישהה עליותיו
The Gemara presents a second version explaining why Beis Shammai does not allow being mechalel silver coins of maaser sheni onto gold coins (according to the Amora that Beis Shammai agrees that gold is considered currency): Beis Shammai holds that the word "הכסף"– the money (of maaser sheni to be spent in Yerushalayim), כסף ראשון ולא כסף שני – it teaches that it must be the first money, and not the second money (i.e., one cannot be mechalel money of maaser sheni onto other money). Accordingly, Beis Shammai would even disallow being mechalel silver dinarim onto other silver dinarim. This version is eventually disproven, and the Gemara presents another: Beis Shammai holds the Rabbis prohibited being mechalel silver selaim onto gold dinarim: שמא ישהה עליותיו – because perhaps one might delay his ascents to Yerushalayim, if his silver coins of maaser sheni do not add up to a gold dinar, and he may not bring his silver coins with him. Beis Shammai agrees that one may be mechalel produce onto gold dinarim, because he will not delay redeeming them until he has enough for a dinar, since produce spoils.
- Machlokes if מטבע נעשה חליפין
The Gemara presents a machlokes between Rav and Levi if coins can be used to effect חליפין. One says: מטבע נעשה חליפין – a coin can be used to effect חליפין, and the other says it cannot. Rav Pappa explains the second opinion: משום דדעתיה אצורתא – because [the seller’s] mind is on the figure on the coin, וצורתא עבידא דבטלא – and the figure often becomes voided by the government. Therefore, a coin is not considered “whole,” which is a requirement for חליפין. The Gemara asks that the Mishnah, which taught that one party’s taking gold coins “acquires” silver ones for the other, seems to prove that חליפין can be made with coins!? The Gemara answers that the Mishnah’s case where the silver is given בדמים – as money payment, and not an exchange of חליפין. As such, the Mishnah should be understood as saying that acquiring the gold coins is מחייב – obligates the buyer to pay silver, because the purchase is complete, not that the seller owns the silver coins. This is supported by the Mishnah’s next case, that one party’s acquiring silver coins does not acquire gold coins for the other, which would not be true if the Mishnah was discussing חליפין.
