1) A CLAIM OF "HEZEK RE'IYAH"
OPINIONS: The Rishonim rule in accordance with the second version ("Lishna Achrina") of the Gemara that Hezek Re'iyah is considered Hezek. Accordingly, when partners divide their property, one may force the other to build a wall between their portions.
What is the Halachah in a case in which partners divide the property but do not build a wall, and then a few years later one of the partners insists that the other one should share in the expense of building a wall to prevent Hezek Re'iyah? The Gemara later teaches that a person is able to procure a Chazakah to use his property in a way which disturbs his neighbor (6a; see Hagahah in Rashi, DH Achzik l'Hurdi). Will such a Chazakah work with regard to Hezek Re'iyah as well?
The Rishonim write that a Chazakah will not help to counteract a claim of Hezek Re'iyah, and they offer a number of reasons.
(a) The ROSH (1:2) and the RA'AVAD (cited by the Rashba) write that a Chazakah will not be effective because each of the neighbors damages the other in an equal manner. Therefore, each neighbor may claim that the reason he did not protest the Hezek Re'iyah earlier is "because I did not want to provoke my neighbor to protest the Hezek Re'iyah that I was causing, so instead I waited for him to register his protest of Hezek Re'iyah until I registered my protest." According to this explanation, if only one of the two neighbors is causing Hezek Re'iyah, such as where one's roof is adjacent to his neighbor's courtyard, where the owner of the courtyard suffers Hezek Re'iyah, then the perpetrator of the Hezek Re'iyah is able to make a Chazakah if the victim does not protest.
(b) The RIF (in a Teshuvah cited by the Rashba) and the RAMBAN write that there is no Chazakah for Hezek Re'iyah since it is a constantly occurring damage and it is not possible for one neighbor not to see what the other is doing. Therefore, it is comparable to causing smoke to go into his neighbor's property, a form of Hezek for which a person can never make a Chazakah.
(c) The RI MI'GASH writes that a Chazakah can be obtained only through an action, such as by building a window into one's wall opposite his neighbor's property. Hezek Re'iyah does not involve an action which changes the status quo, since both neighbors continue to use the Chatzer as it is, and therefore it cannot be considered a Chazakah.
The Teshuvas ha'Rif cites proof to the ruling that a Chazakah does not work in the case of Hezek Re'iyah from the first version ("Lishna Kama") of the Gemara. The Gemara (2b) asserts that if the word "Mechitzah" in the Mishnah means a wall, then the law that the neighbors must agree to build a wall (and cannot force each other to build it) is proof that Hezek Re'iyah is not considered Hezek, because otherwise they could force each other to build a wall. If a Chazakah can be made to counteract a claim of Hezek Re'iyah, then the Mishnah might be referring to a situation in which both partners do not protest the other's Hezek Re'iyah, and therefore they each have a Chazakah. Since they each have a Chazakah, that is why they do not have to build a wall unless both consent to do so. It must be that it is impossible to make a Chazakah for Hezek Re'iyah, and one neighbor can always force the other to help build a wall because of Hezek Re'iyah (according to the view that Hezek Re'iyah is considered Hezek).
The Rishonim do not seem to view this as an irrefutable proof. They do not explain, however, how the proof can be refuted.
REBBI AKIVA EIGER (2a) explains that the refutation might be from the second part of the Mishnah. The Mishnah says, "v'Chen b'Ginah," which means that in a Ginah, even if the partners do not agree to build a wall, they may force each other to do so because of "Ayin ha'Ra" (as the Gemara explains on 2b). If the Reisha of the Mishnah is discussing neighbors who each had a Chazakah to do Hezek Re'iyah and that is why they cannot force each other to build a wall, then why does the Mishnah differentiate between the wall of a Chatzer and the wall of a Ginah? It is clear that a person can obtain a Chazakah for Hezek Re'iyah in a Ginah as well! This might be why the Gemara assumes that the Reisha of the Mishnah is not discussing a situation in which a Chazakah was obtained, but rather it is discussing neighbors who are now dividing the Chatzer and have not made any Chazakah.
2) BUILDING A THIN WALL
OPINIONS: The Rishonim rule that Hezek Re'iyah is considered Hezek. Consequently, neighbors may force each other to build a six-Tefach thick wall between their two portions of land when that is the customary practice of that place ("Minhag ha'Medinah").
The Gemara discusses a case in which the partners build the wall equally on both of their portions of land. What is the Halachah in a case in which one of the partners offers to build the entire wall in his portion, but to make it much thinner than the local custom in order to save the land and expenses of building a thick wall?
(a) The ROSH (1:5) writes that one is permitted to build a thin wall (even a wooden fence) in one's own lot, thereby avoiding the expenses of a thick wall. He explains that the logic of why each of the neighbors may force the other to build a thick wall in accordance with the customary practice in that place is because he could say that he does not agree to give up space in his lot unless he feels that the wall be a strong and enduring one. If the wall is not being built in his yard, he may not protest the fact that the wall that his neighbor builds is not strong and enduring.
The Rosh proves this from the Gemara earlier (2b) that says that when a person has a roof adjacent to his neighbor's Chatzer, the owner of the roof must make a "Ma'akeh" four-Amos high. Why does the Gemara call this partition a "Ma'akeh" and not a "Kosel"? It must be that since only one person is building this partition (since the owner of the Chatzer is not damaging the owner of the roof with Hezek Re'iyah), he is not required to build it in accordance with the required thickness of the wall as described by the Mishnah.
The Rosh cites a second proof from the Beraisa which teaches that the owner of a wheat field may force his neighbor, the owner of a vineyard, to build a wall between the two fields. The Beraisa does not say that such a wall must be built according to the measurements described in the Mishnah. (This proof might be refuted by suggesting that there never was a Minhag ha'Medinah to build such thick walls in a vineyard.)
(b) The RASHBA writes that even if one neighbor builds the entire wall in his lot, he still must build it in accordance with the customary practice (i.e. six Tefachim thick). If that would not be the Halachah, but rather a person could choose to build a thin wall in his own property, then who would ever agree with his neighbor to build half (three Tefachim) of a thick wall on his lot when he could avoid the expense by building a very thin wall on his own property?
(The Rosh alludes to the answer to this question. A person might not want to build a thin wooden fence on his property, because ultimately he will not save money since it will collapse more easily and he will have to bear constant expenses to rebuild it.)
The Rashba defends his ruling on logical grounds. He says that if one neighbor wants to build a thin wall, the other neighbor may insist that a thin wall is not sufficient because it will easily collapse and he will constantly have to bring his neighbor to court to force him to rebuild it.
REBBI AKIVA EIGER (2a), in the name of his brother, cites proof for the view of the Rashba from the Gemara's first version ("Lishna Kama"). Why does the Gemara conclude that if partners must agree to build a wall then it must be that Hezek Re'iyah is not considered Hezek? Perhaps the Mishnah states that they must agree to build a wall because if they do not agree, it is not necessary to build it in accordance with the Minhag ha'Medinah, because one may build a thin wooden fence in his own portion of the Chatzer!
Rebbi Akiva Eiger refutes this proof in the same way that he refutes the Rif's proof (as mentioned in the previous Insight). If the Mishnah is discussing a situation in which one of the neighbors wants to build a thin wall in his own portion of land, then why does it imply that this would not be permitted in the case of the wall of a Ginah? If the neighbor of a Ginah agrees to build a wall in his own domain which is not in accordance with the measurements of the Minhag ha'Medinah, then he should be permitted to do so, just as he is permitted to build such a wall when two Chatzeros neighbor each other (according to the Rosh). Since the Mishnah does differentiate between a Ginah and a Chatzer, it is evident that it is not discussing a situation in which one of the neighbors wants to build the wall by himself.
3) DISMANTLING A "BEIS HA'KENESES"
QUESTION: The Gemara gives two reasons for the prohibition against destroying one Beis ha'Keneses before a new one is built. It is prohibited either because of the fear that the people will neglect rebuilding the new Beis ha'Keneses, or because they will not have a place to pray in the meantime. The Gemara then relates that Mereimar and Mar Zutra would dismantle and rebuild the summer Beis ha'Keneses in the winter and the winter Beis ha'Keneses in the summer.
Since they did not rebuild the new Beis ha'Keneses before they dismantled the old one, why were they not concerned that the synagogue that they dismantled might not be rebuilt?
(a) The TOSFOS YESHANIM (see MAHARSHA) explains that their construction project did not involve building a different Beis ha'Keneses. Rather, they made structural modifications to the existing building in order to accommodate it for the conditions of winter or summer as necessary. The Gemara says that when a weakness is found in the structure of a Beis ha'Keneses, it is permissible to dismantle it in order to correct the structural deficiency, even before building a substitute Beis ha'Keneses. Here, too, the fact that the present Beis ha'Keneses was not fit to tolerate the weather conditions of the season was considered as though the Beis ha'Keneses had a structural deficiency and thus they were permitted to dismantle it.
(b) The Tosfos Yeshanim suggests further that when there is another Beis ha'Keneses available, there is no concern that the people will neglect building a new one, since there is still a Beis ha'Keneses in which to pray. This answer is consistent with the Girsa cited by the Mesores ha'Shas, which states that there is concern for neglect even when there is a "place to pray," meaning an unoccupied house or other building (but not a Beis ha'Keneses). If, however, there is another fully-operative Beis ha'Keneses available, then there is no concern for neglect in rebuilding the old one.
This is also the answer of the RAMAH. The Ramah adds that even when there is no other comfortable place to pray, an existing Beis ha'Keneses should not be dismantled unless it is during a season in which it is not used. This is why the Gemara emphasizes that Mereimar and Mar Zutra dismantled the summer Beis ha'Keneses in the winter -- they would not have dismantled it in the summer when it was in use.
(c) The RASHBA and Tosfos Yeshanim suggest further that the opposite might be true. The concern for neglect applies only when there is another fully-operative Beis ha'Keneses in which to pray. Since the people already have another comfortable Beis ha'Keneses in which to pray, they might be neglectful about rebuilding the second Beis ha'Keneses. However, when the other Beis ha'Keneses is not as comfortable as the one that needs to be rebuilt, as in the case of Mereimar and Mar Zutra (where the existing Beis ha'Keneses would have been uncomfortable in the summer), there is no concern that the people will neglect to rebuild the old Beis ha'Keneses. (This is consistent with the other Girsa printed in the Gemara, which says that there is concern for neglect when there is "another Beis ha'Keneses," referring to a fully-operative Beis ha'Keneses.)
(The Tosfos Yeshanim suggests a fourth answer which the TORAS CHAIM strongly rejects.)
(d) The ROSH (1:4) writes that Mereimar and Mar Zutra indeed maintain that the only reason why a new Beis ha'Keneses must be built before the old one is dismantled is in order that there be a place to pray. Since they had another Beis ha'Keneses, they were permitted to dismantle the winter Beis ha'Keneses during the summer.
Is this the Halachic opinion? Is there indeed no concern for neglect when there is another Beis ha'Kenes in which to pray?
The Rosh and other Rishonim write that the Gemara later seems to favor the first opinion, that there is concern for neglect. Ravina suggests that perhaps it is permitted to dismantle a Beis ha'Keneses if the money and building materials for the new Beis ha'Keneses are already prepared. If the problem with dismantling the old Beis ha'Keneses is that there might not be a place to pray, then what difference does it make if the building materials are prepared? The problem with dismantling an old Beis ha'Keneses before building a new one is the concern that the rebuilding of the new Beis ha'Keneses will be neglected. That is why there is no concern for neglect when the construction of the new Beis ha'Keneses has begun (by preparing the building materials).
The RAMAH writes that the same conclusion may be drawn from the conclusion of the Gemara in which the Gemara says that Bava ben Buta was correct in telling Hurdus (Herod) to dismantle the Beis ha'Mikdash before reconstructing the new structure, since "Malchusa Sha'ani d'Lo Hadra Bei" -- the king does not change his mind. However, when the Beis ha'Mikdash was dismantled, there was no other place in which to offer Korbanos. What difference does it make if the king will not change his mind? It still should be prohibited to dismantle the Beis ha'Mikdash even temporarily, because there would be no place to offer the Korbanos in the interim! It must be that the concern is only for neglect in rebuilding it, and in the case of a king there is no concern for neglect.
The TORAS CHAIM and RASHASH do not agree with this reasoning. Even during the three years during which the Beis ha'Mikdash was dismantled, the Korban Tamid was still offered. The Gemara in Megilah (10a) teaches that "Makrivin Af Al Pi she'Ein Bayis" -- when building the Heichal it is permitted to offer the Korbanos as long as the Korbanos are brought in the place of the Mizbe'ach.
The Ramah might mean that although most Korbanos may be brought in the manner described in Megilah (10a), some annual Korbanos cannot be brought in that manner, such as the Par and Se'ir of Yom Kippur, the blood of which must be sprinkled in the Kodesh ha'Kodashim, on the Paroches, and on the Mizbe'ach ha'Ketores. At the moment that the Beis ha'Mikdash was dismantled, there was no place to bring those Korbanos until it was rebuilt.
4) THE WHIM OF ROME
QUESTION: The Gemara explains that Bava ben Buta permitted Hurdus to dismantle the Beis ha'Mikdash in order to rebuild it without first building a substitute, because "Malchusa Sha'ani d'Lo Hadra Bei" -- the king does not change his mind. Thus, there was no risk that Hurdus would not complete his plans.
How could they be so certain that Hurdus would finish the project that he started? The Gemara later relates that Hurdus was subject to the whims of the Roman Empire, and he was able to get away with the rebuilding the Beis ha'Mikdash only because he built it before Rome found out about it. It seems that the principle that a king does not change his mind is not applicable here, since Hurdus did not have unlimited power. (RASHASH)
ANSWER: The reason why a king always completes what he starts is that he realizes that if he does not keep his commitment, his power over the kingdom will be weakened. For this reason, Hurdus would never have begun a project unless he was absolutely certain that he would be able to complete it and that he would not be stopped by the powers in Rome. The Gemara means that Bava ben Buta felt comfortable leaving the decision to reconstruct the Beis ha'Mikdash in the hands of Hurdus, because he knew that Hurdus would not begin the project and dismantle the Beis ha'Mikdash unless he was absolutely certain that he would be able to complete the project and not risk weakening his power over the kingdom. (M. KORNFELD)