Literary critic Adam Kirsch is reading a page of Talmud a day, along with Jews around the world.What is the proper relationship between Jews in the Diaspora and Jews in the Land of Israel? For much of Jewish history, that question didn’t have to be asked; from the dark ages until the late 19th century, the Jewish population of Eretz Israel was tiny enough to be ignored by Jews living elsewhere. But in our own time, the question has returned to the center of Jewish life. Every month, it seems, another American Jewish writer publishes a book about Israel, either to praise or, more often recently, to condemn; and these books are in part arguments about the validity of Diaspora Judaism. As Liel Liebovitz explained recently in Tablet, there is a core of nationalism in the Jewish faith that Diaspora Jews always have to wrestle with. Whenever Jews in America discuss Israel, we are implicitly staking a claim about the validity of our own Jewish identity.This complex of questions was raised, in a different form, in this week’s Daf Yomi reading. For the Jews of the Talmudic era, the relationship between Judaism in the Diaspora—which meant, primarily, in Mesopotamia, where the Babylonian Talmud was compiled—and Judaism in the Land of Israel presented itself as a problem not of politics but of jurisprudence. Much of Jewish law is only effective inside the Land of Israel—the rules relating to agriculture, for instance. Yet by the third and fourth centuries C.E., Jewish life in what was then called Palestine was oppressed and impoverished, and the center of Jewish legal thought had moved to the academies in what is now Iraq. But how could the rabbis of Babylonia justify laying down the law to rabbis in the Jewish homeland?Reish Lakish addressed this issue in Sukka 20a, in the course of a discussion about whether reed mats are acceptable for use as sukkah coverings. The rule about valid sukkah roofing, as we saw last week, is that it must be made of plant matter detached from the ground; but it can’t be made of edible plants or of materials fashioned into vessels or utensils, since these things are capable of conveying ritual impurity. Reed mats present a problem because, while reeds themselves are acceptable roofing, a mat that is meant for sitting on is capable of becoming tamei—for instance, if a man who has recently had a seminal discharge, a zav, sits down on it. The rabbis distinguish, therefore, between small soft mats, which are clearly intended for sitting on, and large coarse mats, which are presumably meant only for use as roofing material.In the course of this debate, the Talmud has one of those moments of linguistic slippage that reveal the cultural gap between the Hebrew-speaking Tannaim of the Mishna and the Aramaic-speaking Amoraim of the Gemara. The Mishna uses the term hotzalot and the Gemara queries it: “What is the meaning of hotzalot?” Reish Lakish says it means simply “mats,” but Rabbi Abba translates it with the Aramaic word mezablei, a kind of leather feed bag for animals. There is a pathos hidden in this small exchange: The rabbis of Babylonia are slowly losing touch with the everyday words of the Holy Land.At this point, Reish Lakish—who was born in Syria but moved to Palestine as an adult—offers a brief but pointed statement about the relationship between Babylonia and Israel. “Initially, when Torah was forgotten from the Jewish people in Eretz Israel, Ezra ascended from Babylonia and reestablished it,” he explains. When the Torah was “again forgotten, Hillel the Babylonian ascended and reestablished it.” And when the law was forgotten for a third time, in the Tannaic period, “Rabbi Chiyya and his sons ascended and reestablished it.” Reish Lakish goes on to cite the teaching of Chiyya on the question of reed mats.This little genealogy of Diaspora relations sends a powerful message, reminding us that the question of the Diaspora has existed for nearly as long as Judaism itself. It was the Babylonian Exile, following the destruction of the First Temple in 586 B.C.E., that established the first Jewish Diaspora community, one that lasted until the disruptions of 1948. Without Ezra, a leader of the Babylonian Jewish community, the Second Temple would never have been built; without Hillel and Chiyya, Babylonian-born rabbis, the Jews of Israel would have allowed the proper interpretation of the law to be forgotten. Judaism, Reish Lakish shows, always strives to be established in the Land of Israel, but its authentic traditions may survive best in exile. The Diaspora is a resource that Eretz Israel cannot live without.This large insight comes at the end of a chapter largely devoted to technical matters. In discussing the proper way to build a sukkah, the rabbis rule on a variety of different building styles and materials. The key to the sukkah is that it must be purpose-built—otherwise, it does not fulfill the biblical command to remember the tents of the Israelites wandering in the desert. But there is a natural tendency to build the sukkah using materials already at hand, and the rabbis have to decide exactly how different a sukkah must be from an ordinary house.Can you, for instance, roof your sukkah with wooden boards? The Mishna on Sukka 14a is inconclusive, but in the Gemara, Shmuel says that it depends on the width of the boards. Boards that are four handbreadths wide resemble ordinary ceiling planks and can’t be used; but boards that are narrower than this “are merely reeds,” and so they count as valid roofing. This does not apply, however, if the four-handbreadth-wide board is directly adjacent to the wall of the sukkah. In that case, the Talmud invokes the principle of “curved wall,” which allows you to count the board as simply an extension of the wall, and not part of the roof itself. And Rabbi Yehuda notes that an exception to the four-handbreadth-rule was made during “a time of danger”—a legal category that occurs sadly often in the Talmud—when Jews would use ordinary ceiling boards in order to disguise the sukkah, making it look like merely an addition to the house.In Sukka 15a, the rabbis consider another possibility. Imagine the ceiling of your house is already made of boards, with no coating of plaster holding them in place. Could these boards be considered a valid sukkah roof? The answer is no, because of the principle of “Prepare it, and not from that which has already been prepared”: that is, the sukkah must be built especially for that purpose, and not simply an adaptation of an existing structure. However, the rabbis are content if this principle is merely honored by a token observance. Thus if you remove one of the boards of your existing roof and replace it with sukkah roofing—or, according to Beit Hillel, if you merely rearrange the boards of your roof—you can create a valid sukkah. The roof doesn’t actually have to be purpose-built from scratch, so long as something is done to it to mark its new function.Later in the discussion, the rabbis return to a concept that we already met in Tractate Eruvin: lavud or “joining.” According to this principle, a gap in a wall that measures three handbreadths or less is considered legally insignificant; the law treats it as if the segments of the wall were joined together to make an unbroken surface. On Shabbat, this has implications for where you can carry; on Sukkot, it means that there can be a small gap between the roof of the sukkah and the wall. In fact, as Avimi points out, a sukkah that is 10 handbreadths high—the minimum measure—requires only four handbreadths of wall in the middle; the gaps of three handbreadths at the top and bottom are considered joined up by lavud. This principle also has implications for sukkot with skylights, and also for sukkot made from porticoes with columns instead of solid walls. By the end of Chapter 1, we have learned just about everything we need to know about how to build a sukkah. Next week, in Chapter 2, the rabbis will teach us what we actually do in it.***Like this article? Sign up for our Daily Digest to get Tablet Magazine’s new content in your inbox each morning.Adam Kirsch is a poet and literary critic, whose books include The People and the Books: 18 Classics of Jewish Literature.