1) REBBI RULED LIKE REBBI SHIMON WITH REGARD TO MUKTZAH
QUESTION: Rebbi Yehoshua ben Levi relates that when Rebbi went to Diyospera, he ruled that one is permitted to move a lamp while it is lit, in accordance with the opinion of Rebbi Shimon.
The Gemara on the previous page (45b) was in doubt whether Rebbi ruled like Rebbi Yehudah or like Rebbi Shimon. Why was the Gemara there in doubt if Rebbi Yehoshua ben Levi explicitly states that Rebbi ruled like Rebbi Shimon? (TOSFOS DH l'Devarav)
(a) The RAMBAN says in the name of TOSFOS that the Gemara earlier was unaware of this incident, and therefore it was in doubt as to how Rebbi ruled.
In a similar approach, the RASHBA says that the Gemara earlier meant that we cannot prove how Rebbi ruled from the Mishnah in Beitzah that it cites. The Gemara knew, though, that Rebbi ruled like Rebbi Shimon from the incident discussed by Rebbi Yehoshua ben Levi in the Gemara here (46a).
(b) The RAMBAN explains that the Gemara earlier knew that Rebbi ruled like Rebbi Shimon with regard to Muktzah Machmas Isur. The Gemara was in doubt whether Rebbi ruled like Rebbi Yehudah even when the object's status of Muktzah is due to the fact that it is not readily available for use (such as the animals that stay outside the city). The PNEI YEHOSHUA gives a similar answer.
(c) The PNEI YEHOSHUA suggests further that we find that it is possible for an object to be Muktzah with regard to eating (Achilah), but not with regard to handling (Tiltul). This implies that Muktzah with regard to eating is more stringent. The Gemara here says that Rebbi ruled like Rebbi Shimon with regard to Tiltul, while the Gemara earlier was in doubt whether Rebbi ruled like Rebbi Shimon regarding eating Muktzah, which is the topic of discussion there.
2) RAVA AND RAV AVYA'S ALTERCATION
QUESTION: The Gemara relates that when Rav Avya visited Rava, he removed his muddy shoes and placed them on Rava's couch. Rava wanted to harass Rav Avya in return by asking him a question he could not answer.
What was the intention behind their conduct? Why did these great Talmidei Chachamim behave in such a way?
ANSWER: RAV YECHEZKEL ABRAMSKY (in CHAZON YECHEZKEL on Maseches Shabbos) in the name of RAV YISRAEL YEHONASAN YERUSHALAYIMSKY suggests a brilliant explanation for the conduct of Rav Avya and Rava.
The Gemara later (124b) says that if a person finds a small shard in the courtyard, it is not Muktzah, because it is considered a Kli (since it can be used for covering pots or other utensils which are commonly found in courtyards, -Rashi DH b'Chatzer). Rava there teaches that even if one finds a shard in Reshus ha'Rabim, it is not Muktzah and may be handled, because had it been found in a courtyard it would have had a use as a Kli. (Since it is a Kli when it is in a courtyard, where pots are commonplace, it is considered a Kli regardless of where it is found, -Rashi). The Gemara there continues and says that Rava was once walking through Reshus ha'Rabim and his shoes became muddy. He picked up a shard and wiped off his shoes, consistent with his own opinion that a shard is not Muktzah in Reshus ha'Rabim.
Rav Avya, however, ruled like the Rabanan there that a shard in Reshus ha'Rabim is not considered a Kli. Accordingly, he wanted to show Rava that one may not use a shard in Reshus ha'Rabim to wipe off muddy shoes, because a shard is Muktzah. He therefore made a point of showing Rava that his shoes were still muddy when he entered Rava's home. Rava was upset that Rav Avya did not want to accept his opinion and that Rav Avya specifically acted in opposition to his opinion. Rava wanted to prove to Rav Avya that his opinion was correct. He therefore pointed out that if an object is considered a Kli because it could be used for covering a pot, then all of the pebbles in the courtyard should not be Muktzah either. It should follow that they should not be Muktzah even if they were in Reshus ha'Rabim (as Rava states on 124b).
(Rav Avya, though, merited Divine assistance and gave the correct answer to Rava's question. Even according to Rava's opinion, a pebble may not be used in Reshus ha'Rabim. Using an object as a cover for other utensils does not give it the status of a Kli; rather, it merely preserves the status of a Kli if the object was already one, such as a shard from a broken clay vessel. -M. KORNFELD)
3) MOVING A BURNING LAMP
QUESTION: The Gemara asks, "Why does Rebbi Shimon prohibit moving a burning lamp?"
What is the Gemara's question? The Gemara (45a) already taught that one is forbidden to move a burning lamp because it is Huktzah l'Mitzvaso, and because it is Huktzah l'Isuro! We know that it is Muktzah. Why, then, does the Gemara ask why Rebbi Shimon prohibits moving it?
ANSWER: TOSFOS (45a, DH v'Ela) explains that when an object is Huktzah for a Mitzvah, one is prohibited only from using it in a way that will detract from the Mitzvah for which it is designated (such as taking oil out of a lamp). Moving the object, however, does not detract from the Mitzvah. Therefore, the reason of Huktzah l'Mitzvaso does not prohibit moving the object according to Rebbi Shimon. (See also RITVA here, who explains this answer more clearly.)
The reason of Huktzah l'Isuro does not apply here because the Isur to which the Gemara earlier referred was that the lamp is a "Basis" to Muktzah (the flame), a concept which the Gemara at this point has not yet introduced. (That is, the lamp is considered Huktzah l'Isuro only according to the conclusion of the Gemara here.) (M. KORNFELD; see Chart #9, and see Insights to Shabbos 45:1.)