1) SUMMARY: PLACING AN ERUV IN A WALL OR IN A "MIGDAL"
OPINIONS: The Beraisa discusses cases of acceptable and unacceptable Eruvin. First, the Beraisa mentions a case in which a person placed food of an Eruv Techumin in a wall with intent to be Koneh Shevisah in a Reshus ha'Rabim. If the Eruv is at a point in the wall higher than ten Tefachim, the Eruv is not valid, because it is in a Reshus ha'Yachid while the person who put it there is in a Reshus ha'Rabim. If the Eruv in the wall is below ten Tefachim, then it is valid.
The Beraisa then discusses a case in which a person intended to be Koneh Shevisah at the top of a Migdal (a large cupboard) that stands in a Reshus ha'Rabim. If the Eruv was placed ten Tefachim or higher in the Migdal, it is valid, and if it was placed below ten Tefachim, it is not valid (as will be discussed below). The Gemara explains that if the Eruv is above ten Tefachim, even if one tips over the Migdal to bring the top of the Migdal to within ten Tefachim of the ground, the Eruv will not be valid.
RASHI gives two explanations for these cases in the Beraisa. According to both explanations, the person intends to make his Makom Shevisah at the top of the Migdal. The difference between the cases is where he actually placed the food of the Eruv.
(a) According to Rashi's first explanation, the person placed his Eruv in the Migdal (that is, on a shelf or compartment that was lower than the one on which he was Koneh Shevisah), either ten Tefachim high in the Migdal or below ten Tefachim. If the shelf on which he placed the Eruv is below ten Tefachim from the ground, then it is in a Karmelis, which is a different domain than the one in which he was Koneh Shevisah (because the top of the Migdal is a Reshus ha'Yachid). If the shelf on which the Eruv was placed is above ten Tefachim, then it is in the same domain as his Makom Shevisah (Reshus ha'Yachid).
An Eruv placed in the Migdal below ten Tefachim is not a valid Eruv because, in order to have a valid Eruv, the food must be in the same place as one's Makom Shevisah. When the Eruv is lower down in the same Migdal as the person's Makom Shevisah, there are three conceivable ways for him to get the food to the place (the top of the Migdal) at which he was Koneh Shevisah:
1. He could raise the food to his Makom Shevisah at the top of the Migdal through internal chimney-type holes which pass through the shelves, from the top shelf to the bottom shelf. This is not possible here because there are no holes in the shelves ("d'Les Lei Kavsa u'Misnah").
2. He could extend his hand, from the top, over the side of the Migdal to reach his Eruv and bring it out to him. This, too, is not a workable solution because it involves the Isur of Moshit (transfer of an object to a Reshus ha'Yachid over a Reshus ha'Rabim).
3. The third way that he could get the food is if he would go out of the place in which he was Koneh Shevisah and bring himself to the food. Rashi says that this will work only when his Makom Shevisah is in the same Reshus as the food. Here, however, the food is in a Karmelis, while his Makom Shevisah is in a Reshus ha'Yachid. If he goes to the food, he will no longer be in the same Reshus in which he was Koneh Shevisah.
Since none of these three options is available in this case, the Eruv is invalid.
When the Gemara suggests that the Eruv (which is below ten Tefachim) should be valid because he could tip over the Migdal, it is using the logic of "Ho'il": since he could tip over the Migdal and thereby move his Makom Shevisah (i.e., the top of the Migdal) into a Karmelis, he is able to bring the food (which is also in a Karmelis) to his Makom Shevisah without a transgression of a Torah prohibition, thus his Eruv should be valid. (This logic is based on the suggestion of Rebbi Yirmeyah (33b) who says that if the location of the food could be altered so that it would be available to him in his Makom Shevisah, the Eruv would be valid. Here, the Gemara suggests a change in the location of the Makom Shevisah, and not in the location of the food, in order to make the food available at his Makom Shevisah.)
The Gemara responds that the logic of "Ho'il" will not validate the Eruv. The Migdal is so tall that if he were to tip it over, the location of his Makom Shevisah (the top of the Migdal) would be moved more than four Amos away from its original location. "Ho'il" validates an Eruv only when the Makom Shevisah could be moved to within the same general vicinity as the original Makom Shevisah, but not if it must be moved farther than four Amos away.
(This is the most straightforward way of understanding Rashi's first explanation. It is the way Tosfos understands the Gemara based on Rashi's first explanation.)
(b) According to Rashi's second explanation, the food of the Eruv is placed in a wall adjacent to the Migdal (and not on a lower shelf of the Migdal), in such a way that it is possible to carry directly from the wall to the Migdal with no Reshus ha'Rabim in between (thus avoiding the problem of Moshit).
(The difference between Rashi's two cases is that in this case, one's Makom Shevisah is in a Reshus ha'Yachid (the top of a Migdal), while in the previous case his Makom Shevisah is in a Reshus ha'Rabim. This causes a reversal of the rulings for an Eruv that is above ten Tefachim and an Eruv that is below ten Tefachim.)
If the food placed in the wall is higher than ten Tefachim from the ground, then it is in a Reshus ha'Yachid and he may transfer the food directly to his Makom Shevisah, which is also in a Reshus ha'Yachid. If the food is below ten Tefachim (such as nine Tefachim high, which is considered part of a Reshus ha'Rabim), then he will have to transfer it from a Reshus ha'Rabim to his Reshus, a Reshus ha'Yachid, which is forbidden. The Eruv is therefore invalid.
The Gemara asks that the Eruv should be valid because he has the ability to tip over the Migdal so that his Makom Shevisah is within ten Tefachim from the ground. He could then bring the food from the Reshus ha'Rabim (the wall) into a Karmelis (the top of the Migdal after it is tipped over). The Gemara answers that the Migdal is so tall that the Makom Shevisah will be four Amos or more away from the original Makom Shevisah after it is tipped over. (According to this explanation of Rashi, the Gemara's answer is the same as in the first explanation.)
(Alternatively, Rashi explains that when one tips over the Migdal, the Eruv remains invalid, because the food in the wall will be four Amos away from the Makom Shevisah at the top of the Migdal, and one may not carry four Amos in a Reshus ha'Rabim; see next Insight.)
2) CARRYING FOUR AMOS IN "RESHUS HA'RABIM" FOR THE SAKE OF MAKING AN "ERUV TECHUMIN"
QUESTION: RASHI earlier (33a, DH v'Hu) writes that even when one's Makom Shevisah is in a Reshus ha'Rabim four Amos or more away from the food, the Eruv is still valid, because he may carry the food to his Makom Shevisah if he walks less than four Amos at a time. To carry in such a manner is not forbidden mid'Oraisa, but only mid'Rabanan, and therefore it is permitted during Bein ha'Shemashos (see Insights to Eruvin 32:3).
However, in his second explanation here (DH Lishna Acharina; see previous Insight), Rashi explains that if one tips over the Migdal, it still will not help to make the Eruv valid because his Makom Shevisah will then be four Amos away from the food, and one may not carry four Amos in a Reshus ha'Rabim.
The TOSFOS HA'ROSH and RITVA point out that Rashi's words are difficult to understand for two reasons:
(a) Rashi seems to contradict himself. Earlier, Rashi writes that an Eruv is valid even if the food is four Amos or more from his Makom Shevisah, because he can carry the food in distances less than four Amos at a time, which is only an Isur d'Rabanan, and bring the food to his Makom Shevisah. Here, however, Rashi says that the Eruv is not valid because the food is four Amos or more away from his Makom Shevisah.
(b) If Rashi retracts his earlier explanation and now maintains that one is not permitted to walk less than four Amos to carry food in a Reshus ha'Rabim even during Bein ha'Shemashos, then why does Rashi a few lines earlier (in his first explanation, DH d'Chi Mamti Lei) not mention that if one tips over the Migdal, it will then be necessary to carry four Amos in Reshus ha'Rabim?
ANSWERS:
(a) Perhaps Rashi does not retract his earlier explanation. Rather, Rashi ignores the possibility that one could carry in increments of less than four Amos because the effectiveness of this particular Eruv is based entirely on the logic of "Ho'il" -- since ("Ho'il") he could tip over the Migdal, the Eruv should be valid. Only one "Ho'il" can work at a time, not a combination of two (TOSFOS 33a, DH v'Ha). In the case of the Migdal, Rashi does not apply a double "Ho'il" and say "Ho'il" that one could tip over the Migdal, and "Ho'il" that he could then bring the food to his Makom Shevisah if he carries it in increments of less than four Amos. (MAHARAM)
(b) In Rashi's first approach, when he explains why the Eruv is not valid when one tips over the Migdal, he cannot say that one would have to carry four Amos in a Reshus ha'Rabim. In that case, the Eruv was on the lower part of the Migdal, in a Karmelis. If one were to carry the Eruv from there to the Makom Shevisah (also in a Karmelis), it would involve an act of Akirah in a Karmelis and an act of Hanachah in a Karmelis of an object carried through a Reshus ha'Rabim. This is not forbidden mid'Oraisa, since the Akirah and Hanachah both did not occur in the Reshus ha'Rabim. (See Insights to Sukah 43:1.)
In Rashi's second approach, however, the Eruv rests in a wall in a Reshus ha'Rabim. When one removes it from there, he performs an act of Akirah in a Reshus ha'Rabim (as well as an act of Hanachah in a Reshus ha'Rabim as well, because of "Mehalech k'Omed Dami"). (M. KORNFELD)

34b----------------------------------------34b

3) AN ERUV IN A PIT
QUESTION: The Mishnah (32b) states that food of an Eruv placed in a tree above ten Tefachim is not valid. However, food placed at the bottom of a pit is a valid Eruv even when the pit is a hundred Amos deep. The Gemara asks what difference there is between a tree and a pit. The Gemara answers that the Mishnah refers to a pit located in a Karmelis. If a person wants to establish his Makom Shevisah at the top of the pit in a Karmelis, his Eruv in the pit is valid, because he may carry the food from the pit, which is a Reshus ha'Yachid, to his place in the Karmelis.
The first part of the Mishnah, which discusses an Eruv placed in a tree, refers to a tree in a Reshus ha'Rabim. If the difference between the first part of the Mishnah and the second part is that the pit is in a Karmelis while the tree is in a Reshus ha'Yachid, the Mishnah should simply teach that the Eruv is valid when placed in a tree in a Karmelis. The first and second parts of the Mishnah would then be consistent. Why does the Mishnah change its discussion from a tree to a pit?
ANSWERS:
(a) The TORAS CHAIM answers that since the floor of a pit is difficult to access and use (see Shabbos 8b, "Tashmish Al Yedei ha'Dechak"), one might have thought that a pit is not a "Makom Chashuv" and that an Eruv placed there would not be valid. Therefore, the Mishnah teaches that a pit indeed is a Makom Chashuv.
The TIFERES YISRAEL gives a similar answer. One might have thought that the Rabanan invalidated an Eruv placed in a pit because they feared that if one is permitted to make an Eruv in a pit, he might dig up dirt from the bottom of the pit when he places his Eruv there, and transgress the Melachah of Chofer, digging on Shabbos. Therefore, the Mishnah teaches that this is not a concern, and the Eruv is valid. (According to this approach, why does the beginning of the Mishnah discuss specifically a tree? There, the Mishnah discusses a case of one who is Koneh Shevisah in a Reshus ha'Rabim. It says that the Eruv was placed in a tree, because it is not normal for a pit to be dug in a Reshus ha'Rabim. A pit is usually dug in a field or other type of Karmelis, but not in a Reshus ha'Rabim. With regard to an Eruv made in a Karmelis, the Mishnah teaches us an additional law with the discussion of an Eruv made in a pit. -M. KORNFELD)
(b) The Mishnah mentions a pit in order to teach that the Makom Shevisah at the edge of the pit is in a Karmelis. As mentioned above, pits are usually located in a Karmelis. The Mishnah teaches that since the Eruv was placed in a pit,the person's Makom Shevisah is in a Karmelis, because that is where pits are usually found.
(c) The VILNA GA'ON (on the Mishnayos) explains that both the tree and the pit are in a Karmelis. The Mishnah does not change two factors from the first case to the second (from a tree to a pit, and from an Eruv in a Reshus ha'Rabim to an Eruv in a Karmelis).
If the Mishnah means a tree in a Karmelis, then why does the Gemara say that the tree is in a Reshus ha'Rabim? Moreover, if the tree is in a Karmelis, then why is the Eruv not valid when placed above ten Tefachim? It is permitted to take the food of the Eruv from a Reshus ha'Yachid (the top of the tree) to a Karmelis during Bein ha'Shemashos. Accordingly, the Eruv should be valid, just as it is valid when placed below ten Tefachim.
The answer is that now that the Gemara determines that the pit is in a Karmelis, one may assume that the tree, too, is in a Karmelis. Nevertheless, there is a difference between an Eruv placed ten Tefachim or above and an Eruv placed below ten Tefachim in the tree. The Eruv is not valid when placed above ten Tefachim, because one needs to perform two acts of Shevus during Bein ha'Shemashos in order to get the food (first, one must transfer from a Reshus ha'Yachid to a Karmelis, and, second, one must use the tree, "Mishtamesh b'Ilan"). Even Rebbi agrees that an Eruv is not valid when it requires two acts of Shevus to be done during Bein ha'Shemashos. In contrast, an Eruv placed in a pit requires only one Shevus -- one must carry from a Reshus ha'Yachid to a Karmelis. There is no prohibition of "Mishtamesh b'Ilan," since the object is at the bottom of the pit and not in a tree. The difference between the first and second parts of the Mishnah thus depends exclusively on the Halachic difference between a pit and a tree.

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