REDEEMING MA'ASER SHENI ONTO GOLD
Suggestion: The following shows that R. Yochanan holds that Beis Shamai forbid redeeming Peros onto gold.
(R. Yochanan): One may not lend a Dinar for a Dinar (lest this lead to Ribis).
Question: To which kind of Dinarim does he refer?
Suggestion: He forbids lending a silver Dinar for a silver Dinar.
Rejection: Surely, all agree that silver is a currency with respect to itself (and permit this)!
Answer: Rather, he forbids lending a gold Dinar for a gold Dinar.
Question: According to whom is this forbidden?
It is not like Beis Hillel. They say that gold is the currency!
Answer: Rather, it is like Beis Shamai. They must hold that it is never considered a currency (therefore, they forbid redeeming Peros onto gold).
Rejection: Rather, R. Yochanan says that Beis Shamai permit redeeming Peros onto gold;
Loans are different. Since regarding commerce gold is the commodity (with respect to silver), we consider its value to fluctuate, therefore also regarding loans, one may not lend it Dinar for Dinar.
Support (Ravin citing R. Yochanan): Even though one may not one may not lend a (gold) Dinar for a Dinar, one may use it to redeem Peros. (He explains the opinion of Beis Shamai, who forbid lending a (gold) Dinar for a Dinar.)
(We conclude that Reish Lakish says that Beis Shamai forbid redeeming Peros onto gold.)
Question (against Reish Lakish - Mishnah #2 - Beis Shamai): One may exchange a full Sela's worth of copper coins of Ma'aser Sheni for silver coins (to lighten his load for his trip to Yerushalayim);
Beis Hillel say, he may exchange half for silver, half he must leave as copper (lest the demand for copper coins in Yerushalayim inflate their price, and the silver coins of Ma'aser Sheni will decrease in value).
Summation of question: Beis Shamai permit redeeming (Peros) onto copper coins. All the more so, they permit redeeming onto gold!
Answer: No. In places where copper is used, it is more accepted than gold.
Version #2 (R. Yochanan or Reish Lakish): (In Mishnah #1,) Beis Shamai and Beis Hillel argue about converting Sela'im to gold Dinarim. Beis Shamai expound "ha'Kesef" - the first money (on which Peros were redeemed) must be brought to Yerushalayim, not second money (on which the first money was redeemed);
Beis Hillel hold that "ha'Kesef" is an inclusion. It permits second money.
All agree that we may redeem Peros onto (gold) Dinarim.
(The other of R. Yochanan and Reish Lakish): They even argue about redeeming Peros onto Dinarim.
(The following three questions are against the first opinion, which holds that they argue about second money.)
Question #1: The Mishnah should rather teach that they argue about redeeming Sela'im onto Sela'im (both of silver)!
Answer: If so, one might have thought that they only argue there, but Beis Shamai admits that one may redeem Sela'im onto (gold) Dinarim, for gold is currency with respect to silver. The Mishnah discusses Sela'im onto Dinarim, to teach that this is not so.
Question #2 (Mishnah #2 - Beis Shamai): One may exchange a full silver Sela in Yerushalayim for (copper) Perutos;
Beis Hillel say, he may exchange half for copper, but he must leave half in silver coins (lest he not spend all of it this festival, and incur a loss due to corrosion, or a second moneychanger's commission if he trades them back for silver).
Beis Shamai do not forbid exchanging silver for copper due to 'second money.' All the more so, they permit exchanging silver for gold, which is more important!
Answer (Rava): The law in Yerushalayim is different. There, "v'Nasata ha'Kesef..." (you will spend the money on any food you desire. Perutos are useful for buying food!)
Question #3 (Mishnah #3 - Beis Shamai): One may exchange a full Sela's worth of copper coins of Ma'aser Sheni for silver coins (before going to Yerushalayim);
Beis Hillel say, he may exchange half for silver, but he must leave half copper. (Beis Shamai do not forbid exchanging coins for coins due to 'second money.' This refutes the first opinion! Therefore, we reject Version #2.)
ANOTHER EXPLANATION OF THE MISHNAH
Version #3 (R. Yochanan or Reish Lakish): (In Mishnah #1) they argue about converting Sela'im to gold Dinarim. Beis Shamai decree lest one delay bringing his Ma'aser money to Yerushalayim (until he has enough to redeem onto a gold coin);
Beis Hillel do not decree. One would (not delay; he would) take the silver coins.
All agree that we may redeem Peros onto (gold) Dinarim. Since Peros rot, one would not delay until he has enough for a full Dinar.
(The other of R. Yochanan and Reish Lakish): Beis Shamai decree even about redeeming Peros onto Dinarim.
Support: According to Version #3, it is clear why Mishnah #1 says 'one may (or may not) convert' (l'Chatchilah), for mid'Oraisa, all agree that one may redeem. According to Versions 1 and 2, the Mishnah should say 'one can (or cannot) redeem' (for Beis Shamai say that even b'Di'eved, it is not redeemed)!
CAN MONEY BE USED FOR CHALIPIN?
(Rav or Levi): A coin can be used to do Chalipin (i.e. through transferring a coin, the seller or giver is Makneh his object to the buyer or receiver).
(The other of Rav and Levi): It cannot be used to do Chalipin.
(Rav Papa): The latter opinion disqualifies it because one relies on the mintage of a coin, and this is prone to be invalidated (the king may change the coins).
Question (against the latter opinion - Mishnah): Gold acquires silver.
Suggestion: The Mishnah implies that gold acquires silver through Chalipin (for then, the silver is truly acquired through transferring the gold. If the Mishnah referred to Kinyan Meshichah, transferring the gold would obligate the buyer to pay silver, but would not actually acquire the silver for the seller.)
Answer: No, it acquires through Meshichah.
Question: If so, it should rather say 'gold obligates silver'!
Answer: Indeed, that is the correct text of the Mishnah.
Support #1 (Reisha): Silver does not acquire gold.
We understand if the Mishnah discusses Meshichah. Gold is the commodity and silver is the currency, therefore silver does not acquire gold.
But if the Mishnah means Chalipin, both should acquire each other!
Support #2 (Beraisa): Silver does not acquire gold: if Reuven sold 25 silver Dinarim for a gold Dinar, even if Shimon did Meshichah on the silver, he does not acquire until Reuven does Meshichah on the gold.
We understand if the Beraisa refers to Kinyan Meshichah. Silver is the currency, therefore it does not acquire gold.
But if it means Chalipin, it should acquire!
Question (Reisha): Gold acquires silver. If Reuven sold a gold Dinar for 25 silver Dinarim, once Shimon does Meshichah on the gold, Reuven acquires the silver, wherever it is.
Granted, if it means Chalipin, he acquires the silver, wherever it is;
But if it means Kinyan Meshichah, why does it say 'he acquires the silver, wherever it is'? Shimon merely owes him the silver!
Answer (Rav Ashi): It refers to Kinyan Meshichah. It means that he acquires the silver, however they stipulated. If he agreed to give new coins, he cannot give old coins, even if they are better.
Question: What is the reason?
Answer: The seller can say that he needs new coins because he plans to keep them for a long time.
(Rav Papa): Even according to the opinion that a coin cannot be used (given) to do Chalipin, it can be acquired through Chalipin;
This is like Rav Nachman says about Peros. It cannot be used to do Chalipin, but it can be acquired through Chalipin.