One who comes to place a wall close to his neighbor’s wall may place that wall close to the neighbor’s wall only if he distances his wall four cubits from the existing wall. Accordingly, the mishna is discussing one constructing a wall close to his neighbor’s wall the first time. Rava objects to this explanation: But the mishna teaches: One whose wall was near the wall of another, which indicates that there had already been a wall there.

Rather, Rava said that this is what the mishna is teaching: In a case of one whose wall was near the wall of another at a distance of four cubits and it fell, he may not place another wall close to his neighbor’s wall unless he distances the wall four cubits from it. What is the reason that this distance must be observed? The reason is that walking here benefits there, i.e., the ground is strengthened by people walking on the land in the area between the walls.

Rav says: They taught that one must leave a space of four cubits between his wall and that of his neighbor only if he builds it alongside the wall of his neighbor’s garden, where people do not usually walk due to the seeds. But with regard to the wall of a courtyard, where people walk, if he comes to place his wall close by, he may place it close by. By contrast, Rabbi Oshaya says: With regard to both the wall of a garden and the wall of a courtyard, if one comes to place his wall close by, he may not place his wall close by.

Rabbi Yosei bar Ḥanina said: And the two amora’im do not disagree, as they are referring to different cases. This statement of Rav is referring to an old city, whose ground is well trodden and stable, and that statement of Rabbi Oshaya is referring to a new city, where even the wall of a courtyard requires walking on its adjacent ground to strengthen it.

With regard to the claim that the halakha of the mishna is due to the need for space for people to walk on the ground between the walls, the Gemara asks: We learned in the mishna: And one who desires to build a wall opposite the windows of a neighbor’s house must distance the wall four cubits from the windows, whether above, below, or opposite. And it is taught in a baraita with regard to this ruling: Concerning the requirement of a distance above, the wall must be high enough so that one cannot peer into the window and see into the window; concerning the requirement of a distance below, the wall must be low so that he will not be able to stand on top of it and see into the window; and concerning the requirement of a distance opposite, one must distance the wall from the windows so that it will not darken his neighbor’s house by blocking the light that enters the house through the window.

The Gemara analyzes this statement: The reason that distance is required opposite the window is so that he will not darken his neighbor’s house by blocking the light that enters the house through the window, but it is not due to the fact that walking will strengthen the ground. The Gemara answers: With what are we dealing here? We are dealing with a wall that is positioned to the side, i.e., perpendicular to the wall with the window in it, and therefore it blocks the light from entering the house through the window but does not prevent walking along the length of the neighbor’s wall.

The Gemara asks: And how far must one distance his wall if it is perpendicular to the other wall? Yeiva, the father-in-law of Ashyan bar Nidbakh, says in the name of Rav: As much as the full width of the window. The Gemara asks: But why is this sufficient? Can’t he still peer into the window if he is that close? Rav Zevid says: This is referring to one who slopes his wall, i.e., he fashions an incline on the upper surface of the wall so that he will not be able to stand on top of it and look through the window.

The Gemara asks: But didn’t we learn in the mishna that one must keep the wall four cubits away from the window? The Gemara answers: This is not difficult; here, he builds the wall on one side of the window, whereas there, in the mishna, he builds walls on two sides of the window. In the latter case, if he builds the walls any closer he will block the light from entering the house through the window even if they are perpendicular.

The Gemara suggests: Come and hear a further difficulty from the mishna below with regard to the claim that the requisite gap between the walls is for the purpose of walking, as the mishna teaches: And one must distance his wall four cubits from a roof gutter so that his neighbor can lean a ladder in the empty space to clean and repair the gutter. The Gemara analyzes this statement: The reason this distance is required is due to the fact that he will be able to lean a ladder, but it is not due to the fact that walking will strengthen the ground. The Gemara answers: With what are we dealing here? We are dealing with a sloping roof gutter, which protrudes beyond the boundary of the wall. As in this case, if the reason for distancing the wall is due to walking, one can walk back and forth beneath it. Nevertheless, a distance of four cubits from the roof gutter is required so that repairs can be performed.

MISHNA: One must distance his ladder four cubits from a neighbor’s dovecote so that a mongoose will not be able to jump from the ladder to the dovecote and devour the birds. And one must distance his wall four cubits from a roof gutter, so that the neighbor can lean a ladder in the empty space to clean and repair the gutter.

GEMARA: Let us say that the mishna is not in accordance with the opinion of Rabbi Yosei, as, if it were in accordance with the opinion of Rabbi Yosei, doesn’t he say with regard to planting a tree next to a neighbor’s cistern: This one digs within his land, and that one plants within his land, and neither individual need consider what is happening in the property of the other?

The Gemara answers: You may even say that the mishna follows the opinion of Rabbi Yosei, as didn’t Rav Ashi say: When we were studying in the study hall of Rav Kahana, he would say to us that Rabbi Yosei concedes with regard to his arrows, i.e., he concedes that one must distance himself if his actions will cause damage to his neighbor. Here too, sometimes when he places the ladder, the mongoose might be sitting in a hole and will immediately jump up and climb the ladder to the dovecote. The Gemara challenges: But that is indirect damage, as he is not the immediate cause. Rav Tovi bar Mattana said: That is to say that it is prohibited to cause even indirect damage.

The Gemara relates: Rav Yosef had certain small palm trees [talei], and