Please note that unless otherwise indicated, we follow the explanation of Rashi or Rashbam. Consequently, our notes and comments do not necessarily have any bearing on the practical Halachah.

1)

(a) Our Mishnah discusses the Din of partners who want to build a wall to partition their Chatzer - an area in front of the house, where people tended to conduct most of one's affairs.

(b) The Tana rules that, in such a case - they are both obligated to build the wall in the middle of their shared property (with each one supplying exactly half the space.

(c) They are obligated to follow local custom as regards which type of wall to build. If the Minhag is to build a wall of ...

1. ... G'vil - a building-stone six Tefachim thick (as will be explained later), each one must supply a space of three Tefachim; of Gazis, which is five Tefachim thick, then each one provides a space of two and a half Tefachim.
2. ... K'fisin - building bricks four Tefachim thick (as will be explained later), each one must supply a space of two Tefachim; of Leveinin, which is a three Tefachim thick brick, then each one supplies a space of one and a half Tefachim.

(d) Consequently, should the wall ultimately collapse - each takes half the bricks and half the space?

(a) The Tana says that a shared ...

1. ... vegetable-garden - has the same Din as a shared Chatzer, but not ...
2. ... a wheat-field (as will be explained in the Sugya).

(b) A partner who wants a wall in between his neighbor's wheat-field and his - must build it entirely in his own domain. To prove that the wall is exclusively his, he builds a Chazis (a projection along the length of the wall) jutting out in the direction of his partner's field).

(c) If they both want the partition wall - then they must build two Chazi'os, one jutting out in each direction.

(d) The two Halachic differences between the last two cases, should the wall subsequently fall down are - that in the first case, the partner who built the wall takes both the space on which the wall stood and the bricks; whereas in the second case, each partner takes half of each.

(a) The advantage of a dividing wall between Reuven's wheat-field and Shimon's vineyard is - that now Reuven may plant wheat right up to the wall, instead of having to leave a space of four Amos (for Avodas ha'Kerem).

(b) If such a wall collapsed, and after Shimon had rebuilt it, it fell down again, and although they asked him to repair it, he despaired from doing so - the moment the wheat increased by a two-hundredth.

(c) We prove from the Beraisa's choice of the word '*Mechitzas* ha'Kerem" - that 'Mechitzah' in our Mishnah means a stone-wall, too (just like it means there).

(d) Having proved that 'Mechitzah' means a stone-wall, we extrapolate from the Tana's use of the word 'ha'Shutfin *she'Ratzu* La'asos Mechitzah' - that if they do not both agree to build a Mechitzah, one cannot force the other to do so, which teaches us that 'Hezek Re'iyah La'av Sh'meih Hezek' (visual damage [in the form of being watched by one's neighbor as one works in the Chatzer] is not considered damage).

4)

(a) We suggest that perhaps 'Mechitzah' means a partition (halving the Chatzer in two, as in the Pasuk in Matos "Va'tehi Mechtzas ha'Eidah"), in which case the Tana would be coming to teach us - that the moment they agree to partition the Chatzer, they both obligated to build a wall, because 'Hezek Re'iyah Sh'meih Hezek'.

(b) We refute this suggestion however, on the grounds - that the Tana should then rather have said 'ha'Shutfin she'Ratzu La'chatzos'.

(c) We try to counter this by pointing out, that even if 'Mechitzah' means a wall, the Tana should have said 'Bonin Oso' (rather than 'Bonin es ha'Kosel'). We refute this Kashya however, on the grounds - that seeing as Mechitzah also incorporates a Mesipas (a thin wall), had the Tana merely said 'Oso', it would have sufficed to build a Mesipas, and not necessarily a stone wall.

(d) Even though the two partners agreed to build a wall, it is not so obvious that they must each provide half the space for a wall, because, the Tana is talking when Reuven talked Shimon into separating the Chatzer, and we might otherwise have thought that the latter can argue that he only agreed to partition the Chatzer, with a Mesipas, but not a Mechitzah (and that if Reuven now wants a Mechitzah, then he must move back into his own domain and build it).

(a) We reconcile our conclusion (that our Tana holds 'Hezek Re'iyah La'av Sh'meih Hezek') with the continuation of the Mishnah 've'Chein be'Ginah' (which we will later explain to mean that a S'tam Ginah is considered a Makom where the Minhag is to divide it [Tosfos]), by citing Rebbi Aba Amar Rav Huna Amar Rav - who forbids standing in one's fellow-Jew's vegetable-garden when the vegetables are fully-grown, and where Hezek Re'iyah is stronger than that to a wheat-field (see Tosfos 'Ginah Sha'ani').

(b) Even though a wall in a vegetable-garden is more of an obligation than in a Chatzer, as we just explained, the Tana says 've'Chein be'Ginah', implying that they are the same, because he is referring specifically to the type of wall that one is obligated to build ('G'vil or Gazis ... ), and not to the obligation itself.

(c) We reconcile 'Hezek Re'iyah Lo Sh'meih Hezek' with the Mishnah later 'Kosel Chatzer she'Nafal, Kofin Oso Li'vnos ad Arba Amos' - by confining it to a wall that was originally built jointly, and then collapsed (as the Tana specifically says).

(d) The answer seems obvious. When we asked the Kashya however, we understood that the Tana presented the case of a wall that fell down, rather than the original one (even though the Din is the same in both cases) - because of the Seifa, which absolves them from building it higher than four Amos, even though it had been higher before it collapsed.

(a) The Mishnah later obligates each member of the Chatzer to pay towards building a small hut and a little door at the side of the main gate (as will be explained there). The purpose of the side door and the hut - were to prevent people from peeping into the Chatzer and to hire a guard to stop them from doing so, respectively.

(b) We reconcile this with the Tana of our Mishnah, who holds 'Hezek Re'iyah La'av Sh'meih Hezek' - by differentiating between the Hezek Re'iyah of an individual and that of the public.

(c) The Mishnah later implies that if a Chatzer is large enough for each partner to receive four Amos, then one partner can force the other to partition it. If, as we currently hold, 'Hezek Re'iyah La'av Sh'meih Hezek', it will only need to be partitioned - with a Mesipas.

(a) The Mishnah later requires a member of the Chatzer who decides to build a wall in his section of the Chatzer to ensure that it is at least four Amos higher and four Amos lower than all the windows, and four Amos away from them. It needs to be ...

1. ... four Amos higher - to prevent the owner of the wall from leaning on his wall and looking in his neighbor's window.
2. ... four Amos lower - to prevent him from standing on the wall and looking in.
3. ... four Amos away - to prevent him from depriving his neighbor of light.

(b) We reconcile this with our Mishnah which holds 'Hezek Re'iyah La'av Sh'meih Hezek' - by differentiating between the Hezek Re'iyah of a Chatzer and that of a house, where one tends to need more privacy.

(c) In spite of the fact that 'Hezek Re'iyah La'av Sh'meih Hezek', Rav Nachman Amar Shmuel requires Reuven, the owner of a roof that adjoins Shimon's Chatzer, to build a parapet four Amos high at the edge of his roof - because it is more difficult for Shimon, who uses his Chatzer at regular hours, to anticipate when Reuven intends to use his roof, which one tends to use at more erratic times.