1) THE BRANCH FOLLOWS THE TREE
QUESTION: Rav Chisda (7b) says that it is not necessary for Hanachah to be done on an area of four by four Tefachim in order to be a valid Hanachah. The Gemara suggests that Rebbi agrees with Rav Chisda and does not require Hanachah on an area of four by four Tefachim. Rebbi's opinion is expressed in an argument with the Rabanan argue concerning the case of a person who throws an object from Reshus ha'Rabim into Reshus ha'Yachid and it lands on a small protrusion ("Ziz"). Rebbi says that he is Chayav, and the Rabanan say that he is Patur. The Gemara presumes that Rebbi does not require Hanachah on an area of four by four Tefachim, and that is why he says that one is Chayav even when the object lands on a protrusion less than four by four.
Abaye responds to the Gemara's suggestion and says that Rav Chisda is not necessarily following Rebbi's opinion, because Rebbi and the Rabanan are referring to a case of a tree whose branch was in Reshus ha'Rabim and whose trunk was in Reshus ha'Yachid, and a person threw an object from Reshus ha'Rabim onto the branch.
RASHI (DH Shadi Nofo) gives two explanations for the Gemara. According to the first explanation, Abaye is saying that Rebbi's opinion is not consistent with Rav Chisda, and both Rebbi and the Rabanan contradict Rav Chisda's opinion and require Hanachah on an area of four by four Tefachim. The reason Rebbi says that the person is Chayav when the object lands on a branch that is less than four by four is because he maintains that the branch acquires the properties of the trunk, and thus it is considered to have an area of four by four Tefachim.
According to Rashi's second explanation of the Gemara, neither Rebbi nor the Rabanan contradict Rav Chisda's opinion. They both maintain that in Reshus ha'Yachid, Hanachah does not need to be done on an area of four by four Tefachim (because the inside of a Reshus ha'Yachid is considered to be totally filled, as Tosfos writes). Similarly, they both maintain that in Reshus ha'Rabim, Hanachah needs to be done on an area of four by four Tefachim. They only argue whether or not the branch in Reshus ha'Rabim is considered to be an area of four by four Tefachim by virtue of its connection to the tree-trunk.
We may ask a basic question on the Gemara.
According to both explanations of Rashi, the argument between Rebbi and the Rabanan is whether the branch is considered to have an area of four by four Tefachim. Why, then, does Abaye explain that case is where the tree-trunk is in Reshus ha'Yachid and the branch is in Reshus ha'Rabim? The same argument will apply when the entire tree (branch and trunk included) is in Reshus ha'Rabim (according to Rashi's second explanation, or even when both are in Reshus ha'Yachid according to his first explanation)! Why does Abaye insist that the trunk is in Reshus ha'Yachid and the branch is in Reshus ha'Rabim?
(That is, the only thing that changed between the Gemara's initial suggestion and the conclusion is that initially, the Gemara assumed Rebbi and the Rabanan were arguing over whether it is necessary to have a Hanachah on an area of four by four. In the conclusion, they are arguing about whether the branch follows the properties of the trunk or not. If so, what Reshus each one is in is irrelevant!)
(a) TOSFOS (4b, DH b'Ilan) explains that the argument between Rebbi and the Rabanan is not whether the branch has an area of four by four by virtue of its connection to the trunk, but rather whether the branch is considered to be in Reshus ha'Yachid by virtue of its connection to the trunk. They do not argue whether a person who threw an object onto the branch from a distance of four Amos in Reshus ha'Rabim is Chayav for transferring an object four Amos in Reshus ha'Rabim, but rather they argue whether he is Chayav for transferring an object from Reshus ha'Rabim into Reshus ha'Yachid. Abaye explained that the branch and the tree are in two different domains, because that is the subject of their argument -- whether the branch in one Reshus follows the tree in another Reshus! (This is also the MAHARSHA's understanding of the second explanation in Rashi. It clearly is not consistent with the first explanation in Rashi. See also Rashi to 4b, DH Zarak.)
(b) It is true that the Gemara could have said that both the tree and the branch are in Reshus ha'Rabim (or both are in Reshus ha'Yachid). However, the Beraisa refers to a "protrusion," and the normal manner of a protrusion is to project into Reshus ha'Rabim from a Reshus ha'Yachid. Therefore, the Gemara describes the case in such a way. (Based on MAHARSHAL)
(c) We may suggest that the Gemara takes for granted that if the tree and the branch are both in Reshus ha'Rabim, the branch would certainly acquire the properties of the trunk and have an area of four by four Tefachim, because it is just a part of a large tree. The argument between Rebbi and the Rabanan must therefore be in a case in which the different parts of the tree are in different domains. (M. KORNFELD)
2) THROWING A BASKET INTO RESHUS HA'RABIM
OPINIONS: The Gemara says that if one throws a basket into Reshus ha'Rabim, he is Patur. Why is he Patur?
(a) RASHI (DH Rechavah) explains that one is Chayav only for throwing objects from one domain into another, and not for throwing domains. A basket is considered a domain and not an object, because it is ten Tefachim high with a diameter of six Tefachim. This condition is learned from the Melachah as it was performed in the Mishkan, where only objects were thrown from one domain to another but not domains. (TOSFOS YESHANIM points out that although they did not throw domains, they did carry domains from one domain to another, as we see that they carried the Aron and the Mizbe'ach. Apparently, Rashi maintains that one is exempt only for throwing a basket. If one carries a basket into another Reshus, he indeed would be Chayav.)
(b) TOSFOS (DH Rechavah) explains that one is Patur because when he picks up the basket it is a Reshus ha'Yachid, and when it comes to rest it is a Reshus ha'Yachid. His act, therefore, is viewed as an act of throwing the basket from one Reshus ha'Yachid into another, for which one is Patur.
According to this explanation, if the basket was originally lying on its side in Reshus ha'Rabim, one who throws it into a Reshus ha'Yachid is Chayav for Hotza'ah.
(c) The RASHBA explains that one is Patur because wherever the basket is, it is a Reshus ha'Yachid, even while it hurtles through the air. This also seems to be the understanding of the RIF. This explanation differs from that of Tosfos, because Tosfos says that it is a Reshus ha'Yachid only when it lands. Accordingly, even if one moves a basket four Amos along the length of Reshus ha'Rabim, according to the Rashba he will not be Chayav, because it is considered to have remained in its original Reshus. According to Tosfos, however, it should be considered an act of carrying from one Reshus ha'Yachid to another Reshus ha'Yachid through Reshus ha'Rabim, for which one is Chayav (this is the law of "Moshit"; TOSFOS, 2a, DH Pashat).
3) PUSHING A BUNDLE OF STICKS
QUESTION: Rav Yehudah says that one who pushes a bundle of sticks (Zirza d'Kani) in Reshus ha'Rabim is Patur. In what way is this ruling related to the Sugya, which is discussing the definitions of the different domains?
ANSWER: TOSFOS (DH Lo Mechayev) answers that since a person normally lifts up one side of the bundle of sticks and pushes it over the other side in order to move it, we might have thought that it is not considered Hanachah when it rests, the same way that it is not considered a Hanachah when a person puts down his load in order re-arrange it on his back (8a). Therefore, after one has walked four Amos and stops moving the bundle, he should be Chayav. Rav Yehudah teaches that he is Patur. Rav Yehudah's statement, therefore, is loosely related to the Sugya (8a) that discusses a pole which is nine Tefachim tall upon which people re-arrange their loads.
4) A DOORSTEP THAT LEADS TO RESHUS HA'RABIM
QUESTION: The Gemara discusses what the status of "Iskufah" mentioned in the Beraisa (6a) is. The Gemara says that it cannot be an Iskufah of Reshus ha'Rabim, because it would be prohibited for the person standing there to take the object from the Ba'al ha'Bayis in Reshus ha'Yachid, as he would be transferring from Reshus ha'Yachid to Reshus ha'Rabim.
RASHI (DH Iskupas Reshus ha'Rabim) says that the Gemara is referring to a doorstep in front of a Mavoy that does not have a roof beam above it or a Lechi on its outer side to make it part of the Mavoy.
Why does Rashi say that this doorstep is that of a Mavoy, instead of saying simply that it is the doorstep of a house?
ANSWER: The PNEI YEHOSHUA answers that since the Gemara later (9a) will explain (in its first answer) that the doorstep is in front of a Mavoy, Rashi introduces the concept to us here, since it is needed for the answer of the Gemara later in the Sugya.