Literary critic Adam Kirsch is reading a page of Talmud a day, along with Jews around the world.“You shall dwell in booths seven days; all that are home-born in Israel shall dwell in booths; that your generations shall know that I made the children of Israel to dwell in booths, when I brought them out of the land of Egypt: I am the Lord your God.” These verses from Leviticus 23 are the basis for the holiday of Sukkot, one of the three major festivals on the Jewish calendar. In Temple times, Jews would celebrate Sukkot, along with Shavuot and Passover, by making a pilgrimage to Jerusalem. That part of the holiday is now obsolete, but Jews continue the ancient custom of building a sukkah—the word translated as “booth” in the verses above—and eating meals in it for a week. For city-dwellers, this is a chance to recapture in symbolic form the time when the Israelites were a nomadic people, wandering for 40 years in the desert.This week, Daf Yomi readers began Tractate Sukkah, which lays out the rules for the proper celebration of Sukkot. As always, the Talmud thrives on the gap between what is written in the Torah and the actual practices of Judaism. “You shall dwell in sukkot,” the Bible commands: But what exactly is a sukkah? It is clearly something different from a house, but what constitutes the difference? Does any temporary structure qualify, or does the sukkah have to meet certain specifications about height, seating capacity, and building materials?These are the questions the rabbis take up in the first pages of the tractate. The opening mishna lays out one clear rule: “A sukkah that is more than 20 cubits high is unfit.” (A cubit is roughly 18 inches, which would mean that we are talking about a sukkah 30 feet tall.) But the mishna also notes that Rabbi Yehuda disagreed with this ruling, deeming even a very tall sukkah to be valid. Here is an example of the Talmud’s concern for dissenting opinions: What we have is not just a law but a dialogue, which the Gemara tries to explain. Why exactly did the rabbis and Yehuda disagree about the maximum height of the sukkah?The Gemara gives several possible explanations for the 20-cubit rule. According to Rabba, it is because the verse in Leviticus gives the sukkah a memorial function. We dwell in sukkot to remember the years of wandering in the desert; but for this to happen, we have to be consciously aware that we are in a sukkah, rather than simply outdoors. For this to happen, Rabba reasons, a person in the sukkah has to be able to catch sight of the roof whenever he looks around. But a roof that is more than 20 cubits high is too far up to be seen without craning your neck, and so it doesn’t give you the sense of being in a sukkah at all times.This explanation makes more sense as the discussion continues and it becomes clear that, in a sukkah, the walls do not necessarily have to extend all the way up to the roof. Imagine that the walls extended only 10 cubits high, and then there were poles reaching up another 10 cubits to support the roof. In such a sukkah, the open space could create the illusion that you were sitting outdoors, since so much light would come in; and so you would not necessarily remember that you were performing the mitzvah. But in a sukkah whose walls extend all the way to the roof, this would not happen. Your gaze would follow the walls directly up to the top, leaving no doubt that you were sitting in an enclosed sukkah. In that kind of sukkah, then, the Gemara agrees with Yehuda that the roof can be even higher than 20 cubits.But Rabba’s is not the only explanation for the disagreement between the rabbis and Yehuda over the 20-cubit rule. In Sukkah 2a, Rabbi Zeira offers a different biblical verse to explain the matter, this time from the Book of Isaiah, which reads, “And there shall be a sukkah for shade in the daytime from the heat.” This implies that a sukkah is not valid unless its roof gives shade from the sun. But if the walls of a sukkah are more than 20 cubits high, Zeira reasons, then someone sitting inside is not actually in the shade of the roof; he is in the shade cast by the wall itself, which is so high that it blocks out the sun. For this reason, the tall sukkah fails to do its job.These are all theoretical arguments, based on speculative interpretations of Torah verses. But the Talmud gives great weight to the actual practices of leading sages, who are assumed to be living guides to the law; and Rabbi Yehuda has an example of this kind on his side. It involves Queen Helena of Adiabene, the ruler of a small kingdom in what is now Syria, who converted to Judaism sometime around the year 30 C.E., according to the Jewish historian Josephus. Helena became a zealous Jew and a generous patron of the Temple: We met her once before in Tractate Yoma, where it’s related that she donated splendid golden candlesticks to the Temple.According to Rabbi Yehuda, “there was an incident involving Queen Helena in Lod where her sukkah was more than 20 cubits high, and the elders were entering and exiting and did not say anything to her.” Presumably the extra-tall sukkah must have been valid, or else the elders would have spoken up and told Helena to lower it. But the rabbis challenge this conclusion. After all, Helena was a woman, and women are not obligated to build a sukkah; perhaps the elders simply kept quiet because Helene’s sukkah was extra-statutory, and so it didn’t matter whether it was built properly. But Yehuda parries this objection by pointing out that Helena had seven sons, and for their sake the sukkah had to be valid. If the elders didn’t object to it, then a tall sukkah must be permitted.As the discussion continues in this fashion, with each point proposed and debated in detail by various rabbis, a whole series of sukkah specifications emerges. A sukkah must be large enough to hold a man’s head, most of his body, and his table—this is the view of Beit Shammai, which in this case enjoys a rare triumph over the view of Beit Hillel, who believed that a table didn’t have to fit. (In the course of this discussion, we learn the general rule that a house has to be at least four cubits by four cubits to qualify as a legal dwelling—structures smaller than that don’t require a mezuzah.) Furthermore, a sukkah can’t consist of just four posts driven into the ground with a covering on top; it must have two full-length walls and at least a rudimentary third wall.If a sukkah has a maximum height, it stands to reason that there must be a minimum height as well, and indeed the mishna holds that “a sukkah that is not 10 handbreadths high” is unfit. It sounds like just another regulation; but in explaining the biblical basis for this rule, the Gemara ends up speculating on the most sacred matter of all, the nature of God’s presence on Earth. The Divine Presence, the rabbis conclude, never reaches the surface of the Earth; it descends from heaven and stops 10 handbreadths from the ground. Likewise, human beings never reach Heaven, since there is a fixed gulf between God’s region and the human world below. Whenever the Torah seems to suggest otherwise—for instance, when it says that Elijah “went up by a whirlwind heavenward”—we have to conclude that it speaks figuratively. Even Elijah never got closer to Heaven than 10 handbreadths from the ground.The sages deduce this rule by bringing together two seemingly unrelated Bible verses. In Psalm 115, we read, “The heavens are the heavens of the Lord, and the Earth he gave to the children of man.” This establishes the idea of two domains, God’s and man’s, that are spatially separate and nonoverlapping. But how do we know where to draw the line? Here the rabbis turn to the description of the ark in Exodus 25. God, the Torah says, speaks to the Israelites “from above the ark cover.” Now, if you add up the height of the ark and its cover, you get a figure of 10 handbreadths. God’s presence, then, must have hovered at that height. And if God came no closer to the ground than 10 handbreadths in the Ark itself, it stands to reason that he never came lower anywhere else.It is highly characteristic of the Talmud that this cosmic principle should be announced with so little fanfare, in the course of a mundane discussion about the height of the sukkah. It is also a reminder of how differently our ancestors conceived of physical space than we do today. For them, it was quite impossible to ever get higher than 10 handbreadths above the ground (or above the roof of a building, which counted as the ground): You couldn’t jump that high, and there was no machine to take you there. For us, accustomed as we are to jetting around at 30,000 feet, the heavens are neither so inaccessible nor so divine. They are just another region of empty space. If God exists, he must keep withdrawing as we keep reaching higher.