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Why the Talmud Draws Imaginary Lines All Around Us—and Over Our Heads

Daf Yomi: Our literary critic ambles over rooftops, ruins, and ships, in search of meaning in Jewish commentary

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(Photoillustration Tablet Magazine; original photo Powerhouse Museum/Flickr)
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This week’s Daf Yomi reading brought us to Chapter 9 of Tractate Eruvin, an exceptionally dense section, in which some of the previously established rules about eruvs are seemingly overturned. Until now, it had been my understanding that it was only permitted to carry on Shabbat from one private domain—what the Talmud calls a reshut hayachid—to another when they are joined in an eruv. Thus the different houses adjoining a courtyard, or chatzeir, would create an eruv chatzeirot to enable the residents to carry items through their courtyard from house to house.

But in Eruvin 89a, we learn that things are not so straightforward. Take the example of two attached houses, which share a common wall. Each house counts as a separate reshut hayachid for Shabbat purposes; but what about their roofs, which are shared in common between them? Should we consider the whole roof a single domain, or should we draw an imaginary line to extend the common wall between the houses upward, dividing the roof so that each house’s share constitutes a separate domain? And what if the two houses are not the same size, so that one has a larger share of the roof than another: Does that affect how the reshut hayachid is defined?

According to the first mishnah, there are two Tannaitic opinions on this problem. According to Rabbi Meir, “All adjoining roofs of the town are one domain.” Imagine a row of Manhattan townhouses: According to Meir, if you were up on the roof of your house, it would be all right to carry an item all the way down the row of houses to the end of the block, since the whole row constitutes a single reshut hayachid. But this is only the case, Meir specifies, if all the roofs are at the same elevation—“provided that one roof is not 10 tefachim higher or lower.” If a roof is more than 10 tefachim (about two and a half feet) higher or lower than its neighbor, then it constitutes a separate domain, and you can’t carry onto it.

Meir has previously been described as one of the most brilliant and authoritative Tannaim, but in this case, his ruling does not carry the day. Instead, the halacha follows the majority of Sages, who rule that “each roof is a domain unto itself.” This seems like common sense: A roof is in some sense an extension of the house it covers, and so it ought to be considered a separate area, rather than part of a continuous plane of roofs.

But then Rabbi Shimon adds another wrinkle: “Adjoining roofs … are one domain in regard to utensils that began Shabbat in one of these areas, but not in regard to utensils that began Shabbat in the house.” The same holds true of adjoining yards and unenclosed areas. By this logic, if you had a chair on your roof when Shabbat began, it would be permitted to move it to your neighbor’s roof. And if you had a chair in your house when Shabbat began, it would be OK to bring it up onto your own roof, since your house and your roof constitute a single domain. But you could not bring a chair from your house to your roof, and then from your roof to your neighbor’s roof, since your house and your neighbor’s roof constitute two separate domains. (This is always assuming, remember, that you did not create an eruv; if there was an eruv in effect, everything would be different.)

These various rulings of Meir, Shimon, and the Sages are the starting point for a long and complex argument in the Gemara. It is notable that the Amoraim, the rabbis of the Gemara, are just as interested in understanding the logic of Meir’s position as that of the Sages, even though Meir’s ruling does not have the force of law. In a rabbinic argument, every possibility must be thought through, whether it affects actual practice or not. Thus Abaye bar Avin and Chanina bar Avin (their names seem to suggest they are brothers) wonder why Meir insisted that roofs of different heights count as separate domains.

Abaye—a different, more famous Abaye—overhears their conversation and supplies the answer. Meir’s ruling is an example of a law enacted to protect another law. In a public domain, a reshut harabim, anything that protrudes 10 tefachim high and four tefachim wide—such as a post or a hillock—counts as a separate, private domain, so it is forbidden to place anything on top of it on Shabbat. You can’t, for instance, put down a bundle you are carrying and rearrange it on top of a post, then pick it up again. Meir, Abaye explains, did not want Jews to forget this principle, so he applied the same rule to roofs of different heights, as a reminder that a 10-tefachim difference constitutes a difference in domains. His ruling is “a safeguard against doing the same on an elevation in the reshut harabim.”

Soon the Gemara moves on to another problem, involving the rule of gud asik, that is, “extend and raise up.” As we have seen, the Sages allow us to “extend and raise up” the walls of a house in an imaginary line, to create a partition of the roof above. But there is a disagreement between Shmuel and Rav about how to interpret this rule. Gud asik allows you to partition a common roof area into a series of separate spaces, one for each house. This means you cannot carry from one part of the roof to the other.

But what about carrying within each partition? Rav, who “does not apply gud asik,” holds that the roof area does not really have the status of a private domain. Rather, it is a karmelit, a kind of intermediate zone, in which you can carry for no more than four amot at a time (about six feet). Shmuel, who does apply gud asik, holds the reverse: Each roof constitutes a private domain, so you can carry in it without restriction.

But wait, the Gemara objects. First we hear that the Sages do consider each house’s roof a separate domain—that is, they do apply gud asik. Then we hear that Rav does not apply gud asik. How can this be? This is the kind of disagreement between sources that the Gemara loves to examine and, if possible, resolve, and so it is here. To find out what Rav meant, the Gemara consults the traditional teaching “in the academy of Rav,” which preserved his interpretations. According to this school, the Mishnah itself holds that it is only permitted to carry four amot on a rooftop. When it says “each roof is a domain unto itself,” this means simply that the four-amot radius cannot extend from one domain to the other. That is, “one may not carry an object two amot on this roof and two amot on that roof.” In this way, Rav and the Mishnah can both be held to be correct.

This, one might feel, is complicated enough. But in fact, everything I’ve discussed so far is found in just one daf, Eruvin 89a-b—with room left over for a debate about what happens with adjoining asymmetrical roofs, in which one house’s share is bigger than the other. The pages that follow expand, amplify, digress, and complicate. Can you carry from the roof of a house onto the roof of a ruin? What about a ship—do its walls count as the walls of a house, or are they just partitions to keep out the water? What if you were to take the ship out of the water and turn it upside down—then how would the walls be categorized? What about a pavilion, which has a roof but no walls? What if you wore, rather than carried, a hat or scarf from your house into the courtyard, and left it there, and then someone picked it up and carried into another courtyard—would that be an illegal transfer? By the end of this week’s reading, I was left a little dizzy—a condition that never, it seems, troubled the indefatigable Sages.


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Facebook User says:

I definitely hear what Adam is saying about being dizzy… I’ve been studying Talmud for years, and I also found these pages a bit of a hard slog. We Jews are never known for taking the easy way out, though…

One correction: the law actually follows Rabbi Shimon’s view, not that of the majority sages. (This is in keeping with a previously established rule – I think Adam mentioned it in one of his previous columns – that “the law follows the more lenient opinion regarding eruvin.”)

It is also worth noting a short passage on 91a, in which Rabbi Yehudah – a contemporary of Rabbi Shimon – tells of a time when the latter’s opinion was needed in practice: “It happened during a time of religious persecution that we had to carry a Torah scroll from a courtyard to a roof, from a roof to another courtyard, then from the courtyard to an enclosed area – to read from it.” It’s nice to be able to carry beach chairs, but far more important is to be able to preserve Jewish practice no matter what.

Michael Mayer says:

My Talmud teacher R’Breitowitz currently senior lecturer at Ohr Sameach in Jerusalem would tell he class “the last place to find practical ideas if you are erecting an Eruv is the Tractate Eruvin .” As for the textual complexity my Talmud class at T.A. in Baltimore was given by R’ Bobrovsky O’H’ in Yiddish from Aramaic, later discussed in English and Rashi from Hebrew to English. This quadrilateral dialogue was quite daunting at first but it must have sharpened the mind for today I speak seven languages and working on the eighth. I found Mr. Kirsch’s interpretation very impressive in its logic and command of the salient topics and I am looking forward to more forays into the Talmudic world for it is truly a rare talent.

    Isabel Herron says:

    as Dennis responded I cant believe that you able to get paid $6134 in 4 weeks on the computer. did you see this web page w­w­w.K­E­P­2.c­o­m

41953 says:

Too bad Einstein studied physics rather than Talmud. He could have broken new ground on the crucial topic of eruvim.

If I have trouble falling asleep, I will re-read the column.

    Grigalem says:

    Yeah. We got it.

    We got it the first time you made your pointless point, the second time, the third time, the fourth time, the fifth time, the sixth time …………

    Once burned, twice shy, son. From now on you will simply be voted down … and otherwise ignored.

      41953 says:

      Why does Grigalem try to censor opposing voices? Let free speech prevail.

        Facebook User says:

        I can tell you that Grigalem aside, your comments do have at least one reader – me. (Although I had no particular reason to comment in reply, until now.)

        Grigalem says:

        Censor opposing voices?????

        Mentioning that we got it the first time you made your pointless point, and the second time, the third time, the fourth time, the fifth time, the sixth time, etc. is not “censorship”. Just boredom, contempt, dismissal, sarcasm, and like that.


        When you make up new definitions for words just to picture your self as an oppressed minority, you got more problems than we can deal with on a comments section about Kirsch’s summary of the Daf.

          41953 says:

          You are being obnoxious.

          If you are so upset by my viewpoint ignore it.

          Grigalem says:

          Upset? Is this more of your victimology?

          I am moderately annoyed by your posts … because they add nothing to the discussion of the Daf, and they give no one any insight into Adam Kirsch’s reading of the Daf.

          They are just a big fuck you to his entire process of reading the Daf, studying the Daf, analyzing the Daf, arguing with the Daf, and learning what we modern seculars might get out of it if we looked at it his way.

          Frankly, there is enough fuck you in this world, so we don’t need yours.

      Facebook User says:

      Actually, 41953 has made two very good points!

      It is perfectly true that if Einstein had applied his talents to Torah study, we would have gained a great deal in a deeper understanding of eruvin and of many other aspects of Judaism.

      And since what you think about before going to sleep has an effect on your dreams and on the next day – why, then, a column about the Talmud is a great way to prepare for sleep!

      You see, Grigalem, there’s no need to jump on other people and accuse them of “pointless points”; as Pirkei Avot puts it, “Don’t mock any person… for there is no person who does not have his moment.”

        Grigalem says:

        You know what he meant and I know what he meant.

        Being in on the joke and telling everybody that you are in on the joke doesn’t really get you much of anywhere.

          Facebook User says:

          I’m not a mind reader, so no, I don’t claim to “know what he meant.” Indeed, there is the idea in Judaism of dan lekaf zechus, judging others favorably – and looking for the good side of what they say and do – even when the surface evidence points to the contrary.

          (There is also a difference between belligerence, as in some of the comments on last week’s article, and indifference; each of those calls for a different approach. Also, as the Talmud (Beitzah 20b) points out, even when an argument is called for, one has to be careful not to escalate it.)

          Grigalem says:

          You know EXACTLY what the ZIP code meant. Don’t play games.

          Speaking of which, Beitzah 20b is about hens and eggs and holidays. Nothing about escalating arguments.

          Facebook User says:

          Hens and eggs, no (those are discusseed earlier in the tractate); holidays, yes. Well, batting .333 ain’t too bad. :)

          The discussion in Beitzah 20b is about korbanos (offerings in the Holy Temple), and which ones may and may not be brought on holidays. Specifically, one of the issues is whether one may perform semichah (“leaning the hands” on the head of the animal, as per Lev. 1:4); the School of Shammai forbids this, while the School of Hillel allows it.

          The story, then, is that one time a disciple of Hillel was performing semichah on an offering when he was accosted by a disciple of Shammai who challenged him, “What is this semichah (mah zu semichah)?” To which the Hillelite answered, “What is silence (mah zu shesikah)?”

          On which Abayei comments: “Thus we see that a Torah scholar who is confronted with a challenge shouldn’t reply with something beyond what the other said” – in other words, don’t escalate the argument verbally.

          And, as you probably remember from earlier in Eruvin, “Why did the School of Hillel merit to have the halachah established according to them? Because they were gentle and willing to accept insults, and respected the views of the Shammaites by mentioning them ahead of their own.”

          Grigalem says:

          For some reason I went to Beitzah 2b instead of 20b.

Chaim Ehrlich says:

Very well constructed Adam; I enjoyed reading that. Perhaps “Tannaic” is better than “Tannaitic” in the anglicising of Aramic adjectives #alliteration

41953 says:

Grigalem is now dropping the f-bomb. Please see a competent psychologist to deal with your anger issues. Or maybe you can find guidance on how to act like a mentsh in the Talmud. Hillel maybe?

    Grigalem says:

    Your posts add nothing to the discussion of the Daf, and they give no one any insight into Adam Kirsch’s reading of the Daf.

    They ARE just a big fuck you to his entire process of reading the Daf, studying the Daf, analyzing the Daf, arguing with the Daf, and learning what we modern seculars might get out of it if we looked at it his way.

    YOU are saying fuck you to Adam Kirsch and to everyone else … even though you aren’t using that word. We all know a fuck you when we see one. And we don’t need a psychiatrist to recognize one, either.

    There IS enough fuck you in this world, so we don’t need yours.

    Um, you aren’t trying to censor me, are you?

      Facebook User says:

      Grigalem, you surely say Shema at least twice a day, right? Please look at how Yoma 86a explains “Ve’ahavta es Hashem Elokecha” – “sheyehei sheim shamayim mis’aheiv al yadcha.” Also see Taanis 4a, lines 4-13 – especially Ravina’s comment at the end there.

        Grigalem says:

        Rather than spending all of your life evaluating me, my prose style, my language choices, my psychological make-up, my grammar, my knowledge of Talmud, my knowledge of Jewish ethics, my hair style and the color of my kippah ….

        why don’t you worry about Adam Kirsch’s reading of the Daf?

        You know – something other people might be interested in?

          Facebook User says:

          That’s me you’re quoting, not dan. But thank you for the compliment.

          I agree that it would be much better if 41953 was interested in the material being discussed. But you tell me: what’s better – for him to be the Haggadah’s “she’eino yodeia lish’ol” (the one who doesn’t know how to ask, not because he doesn’t know enough to do so but, on the contrary, because he’s indifferent), or the “fifth son” who doesn’t even show up at the Seder? And all four of the children there deserve an appropriate answer.

          In any case, as vital as the study of Torah is, even more vital is to do so in a way that brings about a kiddush Hashem and not, G-d forbid, the opposite. It’s not my place to analyze you and your hairstyle, etc., but I plead with you to consider what the average person is going to think of the Torah, and its students and practitioners, when they come across this page.

          Grigalem says:

          If you think he deserves an appropriate answer than give it to him. I gave him the one I think is appropriate.

          His marrying a non-Jew tells us what seat he is occupying at the Seder – the one in front of the TV or at a poker table.

          You know and I know that no one on Earth is following our conversation … and if they are they are not “the average person”. And if they ARE here they are interested in comments on Adam Kirsch’s take on the Daf …. not what a “fuck all of you time-wasting twits” jerk has to say every week.

          BTW – I spent two months convincing my Talmud teacher (Sanhedrin) to look at this site. It was actually HIS designation of ZIP code’s missives as a “big fuck you”. (He used to be a prison chaplain).

41953 says:

Dear Grigalem,

I know the Talmud better than you do. Calm down and stop your harangues.
Emulate Hillel, not Shammai.


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Why the Talmud Draws Imaginary Lines All Around Us—and Over Our Heads

Daf Yomi: Our literary critic ambles over rooftops, ruins, and ships, in search of meaning in Jewish commentary

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