Literary critic Adam Kirsch is reading a page of Talmud a day, along with Jews around the world.In a week dominated by news of President Donald Trump’s planned border wall, the ethics of walls have been much debated. “Good fences make good neighbors,” the saying goes; but Robert Frost thought otherwise. In his poem “Mending Wall,” he describes walking the length of a stone wall that divides his land from his neighbor’s. The neighbor is a stickler, insisting that the wall be solid, but the poet is doubtful: “Something there is that doesn’t love a wall,” he observes, noting the tendency of walls to topple over, as if Nature wants us to live together, not apart. Walls are made for privacy, and for private property; but what if privacy is not a right, as we like to think? What if it is just a mean kind of anxiety, which keeps us from genuine connection with others? “Before I built a wall I’d ask to know/ What I was walling in or walling out,” Frost writes.This week, Daf Yomi readers began a new tractate, Bava Batra, which begins by considering these same questions about walls. Who builds them, who is responsible for them, and what purpose do they serve? Bava Batra, “the last gate,” is the third tractate in the series that began with Bava Kamma, “the first gate,” and Bava Metzia, “the middle gate.” Originally all three formed a single super-tractate, before being divided for convenience’s sake, and together they cover the subject of damages, or nezikin, which is the title of the seder in which they appear. Bava Kamma focused on personal injury, while Bava Metzia dealt with laws governing property and contract disputes.Now Bava Batra comes to complete the exposition of laws about property ownership and the responsibilities it entails. The introduction to this tractate in the Koren Talmud, which, as always, I am reading in English, explains that Bava Batra differs from its predecessors in one crucial respect. While the earlier tractates based their extensive regulations on biblical commandments—such as the law against theft or enjoining prompt payment of wages—Bava Batra is composed mainly of original rabbinic legislation. The rabbis try to solve disputes based on their intuitions about fairness and justice, and on established custom in the Jewish community.How this happens can be seen in the first mishna of the tractate. Say two people jointly own a courtyard, and they decide to divide it by building a partition. In accordance with basic fairness, the rabbis say that they should divide the land equally, building the wall right down the middle, so that each partner gives up the same amount of land for the wall to stand on. As for what the wall should be made of, here the rabbis leave it up to precedent: “Everything is in accordance with the regional custom,” says the mishna in Bava Batra 2a. They prescribe different thicknesses depending on the building material: The wall should be six-handbreadths wide if it is made of ordinary stones, while it can be just three-handbreadths wide if it is made of closely joined bricks. Each partner is responsible for contributing half the building material.So far, matters are entirely straightforward. The difficulty, and the source of legal interest, arises when one partner wants to build a wall and the other partner does not. Can one compel the other to build the wall, or to pay for its construction? The Gemara points out that what is at stake here is whether there is such a thing as a right to privacy. Does one neighbor have the right to be shielded from the observation of the other neighbor? If he does, then he can force the latter to build a wall, even against his will?Can one compel another to build a wall, or to pay for its construction?Of course, the Talmud does not use the language of rights, which belongs to another era. Instead, it characteristically reduces an abstract concept to a concrete physical problem: Is “damage caused by sight called damage?” That is, can I claim that being observed in my courtyard against my will is a form of injury, which demands redress? The Gemara offers arguments on both sides of the proposition. According to Rav, “It is prohibited for a person to stand in another’s field and look at his crop while the grain is standing.” The reason for this is that the rabbis believed very seriously in the “evil eye,” a Jewish folk belief that persists to the present day. An envious look cast at a neighbor’s flourishing crop might cause it to wither. By this logic, there is such a thing as damage caused by sight, and so one neighbor can compel another to build a wall.But, the Gemara asks, does the logic that applies to a field also apply to a garden, which is used not for growing crops but for recreation? One possible answer comes by analogy with another law, which states that neighbors can compel one another to build a joint gatehouse to a public courtyard, to prevent it from lying open to the gaze of passers-by. If so, it stands to reason that “damage caused by sight is damage”: People have an interest in not being observed. But, the Gemara asks, are the cases really analogous? Maybe there is a difference between the gaze of the general public and the gaze of one neighbor—the former could be considered damage, while the latter could not.Then the Gemara tries a different tack. There is a law that one cannot build a house in such a way that its windows are directly level with the windows of the house next door: The new windows must be four cubits away in any direction. Clearly, the rationale here is to prevent people from being observed inside their own home, so apparently, damage caused by sight is damage. But again, the rabbis raise the possibility that “a house is different.” Perhaps there is an expectation of privacy inside a house that does not apply outside, in a garden. Each assertion is met with a rebuttal, and in the end, it is not clear which side the law takes.The question of whether neighbors must accommodate one another returns a little later in Bava Batra 7a, where the Gemara raises the case of a two-story house that begins to sink. This clearly affects the owner of the ground floor, who will find the ceiling descending on him, but it doesn’t immediately bother the owner of the top floor, whose living space is unaffected. Can the owner of the ground floor compel his upstairs neighbor to demolish the building and rebuild it on a secure foundation? Or can the upstairs neighbor simply say that it is not his problem?The answer is that even if the downstairs neighbor offers to assume all the expenses of the construction, and even if he offers to pay for the upstairs neighbor to rent a new house while the construction goes on, the upstairs neighbor does not have to accept the offer. He can coldly reply, “Crawl on your stomach to go in, and crawl on your stomach to go out.” This would be cruel, but not illegal, according to Rav Huna. But this is only true “when the beams supporting the second story have not reached lower than 10 handbreadths of the ground.” If the second story has sunk to within 10 handbreadths of the ground, it has encroached on the domain of the owner of the first floor, and so the latter has the right to demolish the building. This is one of those cases where good fences—or, perhaps, good foundations—do make good neighbors.***Adam Kirsch embarked on the Daf Yomi cycle of daily Talmud study in August, 2012. To catch up on Tablet’s complete archive of more than four years of columns, click here.