Rava permitted Rebbi Yashiyah and Rav Ovadyah to open a store in Mechuza selling women's trinkets (even though it did not conform with the Halachah that we just learned) because they were Talmidei-Chachamim, and house to house sales would have involved Bitul-Torah.

And Ravina authorized out-of-town basket-sellers (or pot-sellers) to sell their wares in Bavel, in spite of the locals' objections - because they restricted their sales to people from out-of-town.

He only permitted this however - on market-day and in the market (but not via house-to-house sales).

When Rav Kahana, following complaints from the local residents, forbade the wool-merchants to sell their wool in Pum-Nahara they replied that - they had already sold their wool on credit and needed to collect their debts.

He therefore permitted them - to sell sufficient wool to enable them to cover their needs until they had collected their debts (but not a moment longer).

When the Resh Galusa heard that Rav Dimi from Neherda'a was coming to sell his died figs, he instructed Rava to find out whether he was a Talmid-Chacham, and if he was, to give him the authority to sell his goods first.

Rava sent Rav Ada bar Aba with instructions ('T'hi beih be'Kankaneih') to test him, which literally means - 'Smell the jar (to determine whether the wine is good or not [since Torah is compared to wine]).

But Rav Ada was unable to answer the She'eilah that Rav Ada asked him, namely, whether, if an elephant swallowed a wickerwork basket and subsequently let it out as droppings, it is considered digested ...

... in which case it is no longer subject to Tum'ah, or not.

When Rav Dimi asked Rav Ada whether he was Rava, he replied that although he personally was far from the level of Rava, he (Rav Ada) was his (Rav Dimi's) Rebbe, and Rava was his Rebbe. To demonstrate that he did not consider him significant, Rav Ada tapped Rav Dimi on his sandal with his stick.

Rav Dimi came before Rav Yosef following Rav Ada's refusal to grant him the right to sell his goods first, to complain of the bad treatment that he had received.

Rav Dimi from Neherda'a's dried figs - subsequently turned bad.

Rav Yosef reacted to Rav Dimi's complaint - by quoting the Pasuk in Amos which describes how Hash-m did not forgive Mo'av's fourth sin of burning the King of Edom's bones to lime, in order to humiliate him ...

... and if He took the side of the King of Edom, He would certainly take his (Rav Dimi from Neherda'a's) side.

When Rav Ada bar Aba died, many Amora'im (Rav Yosef, Rav Dimi, Abaye, Rava and Rav Rav Nachman bar Yitzchak claimed responsibility for his death them (see Tosfos DH 'Ana'). It is obvious as to why Rav Yosef made this claim. Rav Dimi claimed responsibility because it was due to Rav Ada's refusal to grant him permission that his figs went bad.

The reason that ...

... Abaye claimed responsibility for Rav Ada's death was - because (with reference to Rava's superior Shi'urim), he (Rav Ada) used to invite the Rabbanan to 'come and eat nice juicy meat' at Rava's house (Beis-Hamedrash rather than 'drag bones at the house (Beis-ha'Medrash) of Abaye' .

... Rava claimed responsibility was - because when Rav Ada would go to purchase meat at the same time as Rava's Shamash, he would demand to be served first, since he was greater than him.

Rav Nachman bar Yitzchak too - who would revise with him [Rav Ada bar Aba] his daily D'rashah, before delivering it to the public, claimed that he was responsible for Rav Ada's death.

Rav Nachman bar Yitzchak was once late for the D'rashah, because he was waiting for Rav Ada in order to revise it with him first. The latter was delayed - by Rav Papa and Rav Huna b'rei de'Rav Yehoshua, who wanted details of Rava's Shi'ur on Ma'aser Beheimah, which, for some reason, they had not attended.

When the Talmidim asked Rav Nachman bar Yitzchak why he was late for the D'rashah - he replied that he was waiting for Rav Rav Ada's coffin to arrive.

We finally pin the responsibility for Rav Ada bar Aba's death - on Rav Nachman bar Yitzchak.

Our Mishnah requires a distance of - four Amos between two walls (what exactly the Tana means will be explained shortly).

The Tana also requires Reuven's wall to be at least four Amos away from Shimon's window - incorporating higher than the windows, lower than them, and four Amos away horizontally (as we learned in the first Perek).

Shimon's windows must have been in existence - for at least three years, for this ruling to take effect.

The Tana's statement 'Mi she'Hayah Koslo Samuch le'Kosel shel Chavero, Lo Yismoch lo Kosel Acher Ela-im-Kein Hirchik mimenu Arba Amos' is wrong - because who permitted Reuven to build the first wall within four Amos of Shimon's.

Rav Yehudah's suggestion that the Tana is really coming to prohibit Reuven from building a wall within four Amos of Shimon's existing one is unacceptable - because from the Tana's words it is clear that there was a wall there before, and that he is speaking about a second one.

Rava therefore interprets the Tana's words to mean that - if Reuven's original wall that fell was four Amos away from Shimon's, he must rebuild it not less than four Amos away from Shimon's ...

... because four Amos allows easy access to people to walk between the two walls, and the constant treading strengthens the walls (a Chazakah which Shimon has a right to demand).

Rav restricts the four-Amah gap between the walls to walls of vegetable-gardens (where people do not tend to walk much); walls of Chatzeros, he maintains, do not need it - because people walk on the other side anyway.

Rebbi Hoshaya - requires a gap of four Amos even between walls of Chatzeros.

In fact they do not argue, says Rebbi Yossi b'Rebbi Chanina - because Rebbi Hoshaya is talking about Chatzeros of a new city, which have not yet been trodden in (to which Rav concedes).

We learned in our Mishnah that Reuven's wall must be at least four Amos higher than all the windows, to prevent the owner of the wall from leaning on his wall and peeping in, or four Amos lower, to prevent him from standing on the wall and doing the same, as the Beraisa explains. And the reason for the Mishnah's ruling that Reuven distances his wall from Shimon's, says the Tana of the Beraisa is - to prevent him from blocking Shimon's light.

We can infer from this that - the distance between the two walls is purely a matter of light (and not of treading the earth in between, posing a Kashya on what we just learned ...

... which we resolve - by establishing this Mishnah by an adjacent wall, rather than a parallel one (in which case it is only the corner where the two walls meet that would need to be trodden (too small an area to warrant an enforcement of this law).

Rav Yeiva the father-in-law of Ashi'an bar Nidbach quoting Rav requires the edge of Reuven's wall to be - a distance of at least the width of the window from Shimon's window.

If the wall is as close to the window as that, we are faced with the problem of Hezek Re'iyah (seeing as Reuven is now able to use the top of his wall to peep into Shimon's window). Rav Z'vid dispenses with this problem by - requiring Reuven to slant his wall at the top, bringing it to a point, which prevents him from either standing on it or leaning against it.

We reconcile Rav Yeiva's Shi'ur of 'the width of the window' with our Mishnah which actually gives the distance as four Amos (see Tosfos DH 've'Ha Anan T'nan') - by establishing the former by one wall, whereas the latter speaks about where Reuven builds two walls adjacent to Shimon's window (one on either side) where the Rabbanan are more stringent (see Rabeinu Gershom).

We are about to learn the Mishnah which requires Reuven to build his wall four Amos away from Shimon's gutter - so that Shimon should have room to place his ladder against the gutter and climb up ...

... a Kashya on Rava - who attributes the Shi'ur of four Amos to 'Davsha' (walking in that area and hardening the ground).

To accommodate Rava we therefore establish the Mishnah - by a gutter that is attached to a sloping roof, that protrudes from the wall of the house, leaving four Amos underneath it for walking.

The same Mishnah requires Reuven to place his ladder (next to the wall of the Chatzer) not less than four Amos away from Shimon's dovecote - for fear that a marten might use it to jump at the doves in the dovecote.

When we suggest that the author of our Mishnah cannot be Rebbi Yossi, we mean Rebbi Yossi, who holds - 'al ha'Nizak Leharchik es Atzmo min ha'Mazik', which permits the Mazik to do as he pleases in his own domain (as we discussed above).

To reconcile Rebbi Yossi with our Mishnah, Rav Ashi in the name of Rav Kahana explains that Rebbi Yossi agrees with the Chachamim by 'Giri Dilei', by which he means that - if 'the Mazik's arrows' do the damage [i.e. where he does the damage directly]), then even Rebbi Yossi concedes that the onus is on him to move.

The case of the ladder is considered 'Giri Dilei' - there where the damage is done simultaneously with the placing of the ladder (i.e. where a marten is hiding in a hole in the wall, and as Reuven is placing the ladder, it pounces).

Considering that Reuven did not actually throw the marten, and this is surely no more than G'rama be'Nizakin, Rav Tuvi bar Masni extrapolates from our Mishnah that - 'G'rama be Nizakin (or Garmi, according to those who exempt Garmi from payment), is nevertheless forbidden.