I have several questions on the gemara at the end of 44b, shavas bama'arah:
(a) It seems that if someone dwells in a cave, the top of the cave is not (automatically) included in his techum. Why is that? Is it different from the roof of a house?
(b) In the gemara's case, where the roof of the cave is less than 4000 amos from one entrance to the other, the gemara says that one needs the principle of "havla'as techumin" in order to allow walking across the whole roof from one end to the other. In other words, if we didn't hold by havla'as techumin, if one walked out the south entrance and walked 2000 amos north on the roof, he would be required to reenter the cave and go out the north entrance to continue on the roof (Rashi) - even though when he had gone 2000 amos from the south entrance, he was already standing in the (overlapping) techum from the north entrance. Why is that? What does it have to do with "havla'as techumin"; why isn't it sufficient that he is now actually standing inside the techum from the north entrance?
(c) Why does the gemara give a case where the base of the cave is 4000 amos (and it slants in at the top)? That seems to have nothing to do with it. Couldn't we have picked a case of a 3000 amos cave bottom and top just as well?
(d) Is this cave case brought by the poskim (I didn't see anything marked in the gemara), and if not why not? It seems to be the halacha, and apparently not all that obvious.
Michoel Reach, Baltimore USA
Dear Michoel,
Thank you for the interesting questions on an interesting Gemara.
I have answered the questions below in the order you asked them.
(a) The reason that the roof of the cave is not included automatically in the Techum of the cave -- in the same way that the roof of a house is included in the Techum of the house -- is that it is lacking Mechitzos Nikaros. The only reason that the roof of a house is permissible is because it has Mechitzos Nikaros. Even in a regular house, the Gemara (Eruvin 92) says that if the roof extends out beyond the walls of the house, that the roof has the status of a Karmelis and not a Reshus ha'Yachid, because the walls are not visible from the roof. According to this, in our case even if it was not a cave but rather a large pit that the owner had dug and then covered the pit with a flat roof that was even with the ground, the roof would not be considered a Reshus ha'Yachid, because the walls of the pit cannot be seen.
The Gemara says that if there is a sky light in the roof then the roof -- even if it has an overhang -- is considered a Reshus ha'Yachid because the sky light gives the roof the status of Chorei Reshus ha'Yachid. One might ask: perhaps the entrances of the cave give the roof of the cave the status of Chorei Reshus ha'Yachid? One possible answer to that is that the sky light to the roof is designed so that people can get to the roof and use it and therefore the roof becomes a Reshus ha'Yachid. But the entrances of the cave are there to get in and out of the cave, not to use the roof of the cave. Another possible answer is that even if it is considered a Reshus ha'Yachid, it is not Mukaf l'Dirah and therefore would not be considered like four by four Amos regarding Techumim.
(b) Why should standing in the Techum of the north entrance help anymore than standing in the original Techum in the case of the Mishnah? Havla'as Techumim is a Chidush that combines two Techumim into one big Techum. Without that Chidush it does not help to be standing in the intersection of the two Techumim. Just because both the Techum of the south entrance and the Techum of the north entrance are related to one property (the cave) doesn't mean that they should combine together into one big Techum if they happen to overlap.
(c) The Gemara could have used a case of 3000 Amos to illustrate the concept of Havla'as Techumim (and then the entrances to the cave would not have to be dug at a slant), but the Gemara wanted to use the most extreme case -- a case where a person could walk almost 8000 amos using two Techumim -- the most a person could possibly walk using Techumim.
(d) The case of the cave is not codified in the Rambam and Shulchan Aruch presumably because the case of Havla'as Techumim of the Mishnah is codified and it is a bigger Chidush than the case of the cave -- even though the second Techum did not exist Bein ha'Shemashos it can still combine with his original Techum; certainly the two Techumim of the cave which both existed Bein ha'Shemashos can combine.
Kol Tuv,
Yonasan Sigler
This is not a Psak Halachah
Thank you for very much for the answer(s). I see that they involved time and effort, and I appreciate it. A few questions or comments on some of the answers:
(b) I still don't understand this; I don't see why you would need combining techumin. As an example just "l'saber es ha-ozen", imagine a person walking west out of a city 1000 amos, turning north, circling the city at a distance of 1000 amos, and coming to the eastern side of the city 1000 amos distant. Would anyone say that he has taken advantage of "combining the east and west techumin"? Or would we say, I don't know what you're talking about; he never went more than 1000 amos from the city, so he is of course still inside the techum. He is within 1000 amos of the city; what more is there to say? Here too, he is within 2000 amos of the (entrances to the) cave at all times. Both sides are "his techum". I see that this argument is wrong, but I'm not sure what replaces it.
(c) I don't see why this has to do with choosing the most extreme case. What does the size of the base of the cave have to do with anything? Would the din not be exactly the same if the base were as wide as the roof, a little less than 4000 amos? Or if it were even less wide? The base's width seems to be completely irrelevant, so why tell us?
(d) I guess I'd ask here what's the general practice in the Rambam and Shulkhan Oruch. Do they not normally bring all dinim mentioned in the gemara, even those described as "p'shita" or as being a smaller chiddush than some other din?
Thank you again for your attention.
Michoel Reach
Dear Michoel,
(Answers are according to order of questions:)
(b) The case you give is not a case of two Techumim. It is one Techum that, like all Techumim, extends in all four directions. The case of the Me'arah, however, is two Techumim -- a Techum for each entrance. We agree that if one of the entrances was peramanently closed (filled in with dirt, for example), then there no longer would be that 4000 Amos of area around that entrance to walk in (whereas closing one entrance to the city will not effect the size of the Techum). Therefore, we need the concept of Havla'as Techumim to fuse the two Techumim together.
(c) Let me turn the queation back to you: Why does Rashi (DH Rav Shimi Savar), when discussing the concept of Havla'as Techumim (before getting to the case of the cave), mention the idea of being able to walk 8000 Amos on Shabbos by way of two fused Techumim? Wouldn't it have sufficed to say that one could walk more than 4000 Amos using the concept of Havla'as Techumim? Why specifically 8000? It would seem that using the case of 8000 Amos -- which is the extreme case -- drives home the power of Havla'as Techumim: that it can almost double a person's range of walking on Shabbos. Therefore, in the same vein, the Gemara uses the case of a cave that is 4000 Amos across.
(d) The question is, at most, on the Rambam. The Shulchan Aruch makes no claim to collecting together all the Dinim of the Gemara. The Shulchan Aruch, in fact, following the lead of the Rif and the Tur, is very selective about what Halachos it records. The Rambam, however, makes the claim that when one stocks his library, he can suffice with a Chumash and a copy of his Sefer (see Hakdamah to Yad ha'Chazakah). The Rambam, however, never makes the claim that he is going to record every single Din mentioned in the Gemara. He just says that he will record all of the Dinim necessary to understand all of the Torah she'Ba'al Peh. The Din of the Me'arah is not necessasry to round out one's understanding of Techumim. If ones knows the Din from the Mishnah -- that Havla'as Techumim Milsa Hi -- then the Din of the Me'arah follows in a straightforward manner.
b'Yedidus,
Yonasan Sigler
This is not a Psak Halachah
Thank you again for your reply. Concerning your answer to (a), Why is the roof of the cave not included, I see that your answer is maybe hinted at in the Tosefta Eruvin, Chapter 4, Mishnah 8: [Why is the roof of a building considered as part of the houses in the techum, and the roof of a cave is not?] The roof of a cave is like flat ground, and the roof of a building is like the city.
Ya'asher kochacha.
Thanks,
Michoel Reach
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