Literary criticAdam Kirschis readinga page of Talmud a day, along with Jews around the world.As best I can recall, in my Talmud reading so far there has been only one reference to the Messiah. This came in Tractate Berachot, where one sage was cited as saying that the deeds of the Messiah would not be supernatural, but political—that the only difference between our world and the messianic age would be the restoration of Jewish sovereignty. And it makes sense that messianism should not, at least so far, be a major concern of the Talmud’s rabbis. After all, they are not theologians but legislators, concerned with how Jews should live in the here and now.In this week’s Daf Yomi reading, however, the subject of the Messiah returned, in an utterly unexpected and roundabout fashion. To see how, let’s return to the subject of the Shabbat boundary, which continued to dominate this week’s reading. In Chapter 3 of Eruvin, the rabbis discussed the rules of the techum, the boundary beyond which it is forbidden to walk on Shabbat. That limit, as we have seen, is 2,000 amot, or about 2/3 of a mile. Now, in Chapter 4, they turn to the question of what happens if a Jew ends up outside his techum on Shabbat. The rabbis don’t envision this happening deliberately—as always, the question of what happens to a Jew who deliberately violates Shabbat law goes more or less unanswered. Rather, the Mishnah on Eruvin 41b imagines “One whom gentiles removed from his techum, or an evil spirit”: that is, someone who is made to transgress the boundary without conscious consent.The terms used here seem to conjure a dire picture of Jewish-gentile relations in Talmudic times: Were kidnappings and abductions such a regular feature of Jewish life that they had to be legislated for? But it’s also possible, I think, that this is simply a rhetorical device for illustrating an abstract question: What happens if somehow you end up outside your techum? Likewise, the reference to “evil spirits” doesn’t necessarily mean that Jews were regularly possessed by demons. Rather, it could mean a kind of mental disturbance or distraction that took someone’s mind off the observance of the techum.In any case, the Mishnah instructs that once you are beyond your 2,000-amot boundary, your personal domain becomes a mere four amot—about three square feet, barely enough to move in. This is the minimum necessary to define a “place” in Talmudic terms. However, for Shabbat purposes, any enclosed space, including a house, a corral, or even a city, also qualifies as a place. So, if you are abducted beyond your techum and deposited in a city, you are able to move around anywhere in that city without violating Shabbat. Such, at least, is the lenient view of Rabban Gamliel and Elazar ben Azaryah. Yehoshua and Akiva, on the other hand, would not allow you to move beyond the four amot, even in a city or enclosed place.The Talmud goes on to illustrate this disagreement, and draw out some of its implications, with a story about these four sages—a story that may be less a historical report than a thought experiment. Evidently, the four rabbis were on a ship traveling from a city called “Plandrasin” or “Prandisin”—which the Schottenstein Edition’s notes suggest might be Brindisi, in southern Italy. When Shabbat began, their ship was in port, so that their legal Shabbat residence was established in the city. But then the ship started to move out to sea, putting them more than 2,000 amot from where they started out. The question now became: Were the sages free to move around anywhere in the ship, on the theory that it is a single place? Or were they restricted to the four-amot personal zone? Opinion split along the lines suggested above. Rabban Gamliel and Elazar moved around the ship, while Yehoshua and Akiva “wished to be strict with themselves” and did not move.When the Gemara comes to discuss this incident, in Eruvin 42b, it holds that the law follows the more lenient interpretation of Gamliel and Elazar. There are two possible reasons for this. One, advanced by Rabbah, is that “he established his Sabbath residence within the walls of the ship while it was still day.” That is, because the passenger was on the ship when Shabbat began, the ship itself, rather than the port city, became his Shabbat residence, so he could move anywhere within it.But Rabbi Zeira proposed another explanation, one that invokes principles of physics and mathematics. The passenger is indeed restricted to a four-amot zone, Zeira holds; but since the ship is constantly in motion, the location of that zone is constantly changing with it, being carried along the surface of the sea. As a result, it would be impossible for the passenger ever to leave his personal zone, since as soon as he takes a step, the zone has already shifted with him. (As I mentioned last week, it’s easy to see how this discussion of ships might apply to airplanes today.)Continue reading: The Messiah’s timingDoes it matter whether we accept Rabbah’s explanation or Zeira’s? In either case, the law is the same. But, typically, the Talmud does think the reasoning behind the law matters, because it can have unexpected collateral effects. What happens, for instance, if you are onboard a ship whose walls are less than 10 tefachim high—about two and a half feet? (Whether such a ship could actually exist is another, less important question.) It takes a wall of 10 tefachim to create a legally distinct space on Shabbat. So, if the ship’s walls were shorter than that, the Gemara reasons, Rabbah’s answer would have to change: The ship would no longer qualify as a place, and Rabbah would compel the passenger to stand still in his four-amot zone. Whereas Zeira’s explanation, which is based on the motion of the ship, would still be valid; Zeira would continue to allow the passenger to move about the ship, on the theory that his four-amot zone was in constant motion with him.From this discussion of the height of walls, the Talmud now pivots to a related question: Does a techum boundary extend only 10 tefachim from the ground, or does it continue up in an imaginary straight line? One might think this is a wholly abstract point, because any human being walking on the ground would come in contact with the barrier even if it is only two feet high. Only someone who can fly through the air would have to worry about whether the techum extends indefinitely upward. And in an age before airplanes, no one could fly that high.Except that one person could: the Messiah, who would come down through the sky from heaven. In this way, the Talmud introduces the Messiah into the discussion—not in order to ask questions about redemption or the world to come but simply to answer a technical problem about the imaginary height of a boundary line. For it turns out that the question of whether a techum extends more than 10 tefachim upward has important consequences for when the Messiah might arrive on Earth. If he is coming down from heaven, the rabbis reason, he would have to move more than 2,000 amot, which means that if he came on Shabbat he would be violating his techum. Ergo, it is impossible for the Messiah to come on Shabbat (or on a holiday). Thus, the Gemara says, if a man swears an oath that he will not drink wine once the Messiah comes, he can safely drink on Shabbat, knowing that the Messiah can’t come that day.But this is only the case if the techum does indeed extend upward into the sky. If it does not, if it’s only valid for 10 tefachim from the ground, then the Messiah can simply fly above it. That means he could come on Shabbat as easily as on any other day. And yet there is a tradition, the Talmud acknowledges, that the Messiah will not arrive on Shabbat; and the sages are very reluctant to challenge what seems to be merely a folk belief, on the grounds that if so many Jews believe something, it stands a good chance of being true.If it’s not because of the techum, then, how can we be so sure that the Messiah will not come on Shabbat? It is because, the rabbis explain, the Messiah will be heralded the day before his arrival by the Prophet Elijah. And if Elijah arrived the day before Shabbat, the ensuing uproar would make it impossible for Jews to prepare for Shabbat properly. To preserve the sanctity of Shabbat, then, Elijah and the Messiah will time their arrival so that they come during the week.The collision of the sublime and the pragmatic in this discussion struck me as peculiarly wonderful. It demonstrates the indefatigability of the Talmudists, who were not dazzled by the presence of the Messiah in their argument, but simply took him into account while pursuing their original legal problem. The Messiah becomes one of several variables in the equation they must solve—no more, no less. This is not to say, of course, that if the Messiah did come, the rabbis would not have greeted him in ecstasy. But in the meantime, we need to know how far we can walk on Shabbat, and what time in the morning to say the Shema.***Like this article? Sign up for ourDaily Digestto 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.