QUESTION: In the Mishnah (117b), Rebbi Yehudah says that when a k'Zayis of "Alal" is gathered in one place, it has Tum'as Neveilah (and one who eats it is Chayav). Rav Huna (121b) says that this applies only when the owner gathered the Alal together, thereby showing that he has intention to eat them, and they are not Batel to the hide.

Rav Huna adds that when two pieces of Alal are on the hide, and each one is half of a k'Zayis, the hide nullifies them (and they are not considered Neveilah).

The Gemara asks which Tana in the Mishnah later (124a) does Rav Huna follow. Rav Huna cannot be following the view of Rebbi Yishmael, who says that the hide does not nullify the meat, because Rav Huna says that it does. Rav Huna cannot be following the view of Rebbi Akiva, who says that the hide does nullify the meat, because Rav Huna would not be teaching anything new that Rebbi Akiva did not say already in the Mishnah.

The Gemara answers that Rav Huna follows the view of Rebbi Yishmael. Rebbi Yishmael agrees that the hide does nullify meat that the owner cut off of the animal together with the hide when he flayed the animal. Since he leaves the meat there, he shows that it is Batel to the hide. When Rebbi Yishmael says that the meat is not Batel to the hide, he is referring to a case in which a wild animal pulled off the skin and some meat stuck to it. Since no person did an action to nullify the meat, it is not Batel.

The Gemara asks that if Rebbi Yishmael agrees with Rebbi Akiva that the hide nullifies meat that the owner cut off when he flayed the animal, then Rebbi Yehudah in the Mishnah (117b) follows neither opinion. Rebbi Yehudah, according to Rav Huna, says that when a k'Zayis of Alal -- that came off with the knife -- is gathered in one place, it is considered Neveilah and is not Batel!

If, however, Rebbi Yishmael maintains that even when the owner's knife removed the meat, the meat is not Batel to the hide, then he agrees with Rebbi Yehudah. Who, then, does Rav Huna follow when he says that two half-k'Zeisim of Alal are Batel? The Gemara concludes that Rav Huna follows the view of Rebbi Akiva, and Rav Huna is teaching that Rebbi Akiva maintains that the hide nullifies the meat not only when it was removed with the knife, but even when it was removed by the bite of a wild animal.

How can the Gemara suggest that if Rebbi Yishmael maintains that the meat is not Batel to the hide even when the knife removed the meat, then he agrees with Rebbi Yehudah? Rebbi Yehudah requires that the pieces of meat be gathered together by the owner in order for them to be considered Neveilah (and not Batel), while Rebbi Yishmael mentions no such requirement! (TOSFOS DH Iy)

(a) TOSFOS answers that Rebbi Yishmael does not require that the pieces be gathered, because the case that he is discussing (in which he argues with Rebbi Akiva) is a case in which a wild animal tore off a piece of hide with pieces of meat stuck to it. In such a case he does not require that the pieces be gathered by the owner in order for them to be considered Neveilah. In contrast, when the owner's knife removed the meat with the hide, Rebbi Yishmael agrees that the pieces of meat must be gathered together in order not to be Batel.

(b) Tosfos answers further that it could be that Rebbi Yishmael indeed requires that the pieces on the hide be gathered together in order for them to be considered Neveilah. He does not mention this requirement explicitly because it is already mentioned by Rebbi Yehudah.

QUESTION: The Mishnah states that the skin of a deceased person is Metamei like his flesh. Ula explains that, mid'Oraisa, the skin of a person is not Metamei, but the Rabanan decreed that it is Metamei in order to prevent people from making bedspreads out of human skin.

Why, mid'Oraisa, is human skin not Metamei? It is part of the corpse, and the corpse is Metamei with Tum'as Mes!

(a) RASHI (DH Devar Torah) explains that, mid'Oraisa, skin is Tahor because it is not flesh (Basar) and thus is not considered part of the Mes. (See following Insight.)

(b) TOSFOS (DH Or) explains (based on Nidah 55a) that only parts of the body that are similar to the bones in that they do not regenerate are considered part of the Mes and are Metamei. Skin regenerates and therefore it is not Metamei mid'Oraisa. (Z. Wainstein)

QUESTION: The Mishnah states that the skin of a deceased person is Metamei like his flesh. Ula explains that, mid'Oraisa, the skin of a person is not Metamei, but the Rabanan decreed that it is Metamei in order to prevent people from making bedspreads out of human skin.

Why does Ula say that the Rabanan decreed that human skin is Tamei in order to prevent people from making human skin into bedspreads? There is already a prohibition against deriving benefit from any part of a dead body (Avodah Zarah 29b), and thus no additional prohibition should be necessary. (TOSFOS DH Oros)

(a) TOSFOS in Nidah (55a, DH Shema) and the RASHBA here answer that people tend to be more scrupulous in keeping themselves Tahor than in observing other Mitzvos of the Torah. (The Rashba in Teshuvos 1:365 calls such people "fools.") Therefore, the Rabanan saw a need to decree that human skin is Metamei.

(b) Tosfos in Nidah suggests that the skin of a person is not considered part of his flesh and is not included in the prohibition against deriving benefit from the body of a corpse. This also seems to be the view of RASHI here (DH Devar Torah) and other Rishonim. (The Rashba (ibid.), however, argues and maintains that skin is included in the prohibition.)

The MISHNEH L'MELECH (end of Hilchos Avelus) cites an interesting proof to permit the skin of a corpse. The Navi relates that David ha'Melech gave to Michal for her betrothal (Kidushin) one hundred Philistine foreskins, removed from Philistine warriors that he killed in battle (Shmuel II 3:14). The Mishneh l'Melech asserts that this proves that deriving benefit from the skin of the dead is permitted.

There is a practical difference between these two answers, one which is relevant to a modern medical procedure. It is common to replace a damaged cornea with the healthy cornea of a deceased person. The cornea is the transparent membrane (made of epithelial tissue) that is the outermost cover of the pupil and iris of the eye, which protects the eye from harmful matter and serves as the eye's outer lens. Due to its composition and function, the cornea can be classified according to Halachah as skin. Since its replacement is not always necessary to prevent blindness (in which case its replacement might be classified as Piku'ach Nefesh and would override other Isurim), it is important to determine whether or not one may use the cornea taken from a deceased person. (This question is relevant even with regard to a cornea taken from the corpse of a Nochri, because the Halachah prohibits deriving benefit from any human corpse, whether that of a Jew or of a Nochri. See SHULCHAN ARUCH YD 349:1.)

RAV YECHIEL YAKOV WEINBERG in SERIDEI ESH (2:120) and RAV YEKUSIEL GREENWALD in KOL BO AL AVEILUS permit corneal transplants based on Tosfos in Nidah who permits deriving benefit from the skin of a dead person. Others, however, disagree, asserting that a cornea is considered flesh and not skin. Others permit the procedure on the grounds that using a cornea for a transplant is not considered a normal form of benefit and is "she'Lo k'Derech Hana'asan" (see YABI'A OMER 3:20).

(c) The RADVAZ (Teshuvos 1:262) explains that the skin of a human corpse was considered to have mystical powers of protection. A superstitious person would take the skin of a dead person, and preferably a dead person who was a close relative such as a parent, and bring it with him to war as a talisman for protection. As the Gemara later relates (123a; see Insights there), no Roman battalion went to war without taking along the skin of the head of a dead person (see Rashi there, DH Karkaflin). Accordingly, some considered this to be permitted, reasoning that it did not involve deriving benefit from the corpse (but merely protection). The Rabanan therefore decreed that the skin is Tamei in order to prevent people from using the skin for such purposes.

QUESTION: Reish Lakish asked Rebbi Yochanan whether the skin of the head of a young calf is Metamei Tum'as Ochlin. Is it considered like meat since it is edible, or is it like the rest of the skin which is not food and therefore not Metamei Tum'as Ochlin?

Rebbi Yochanan answered that it is not considered food and is not Metamei Tum'as Ochlin. Reish Lakish asked that the Mishnah (122a) explicitly states that it is Metamei Tum'as Ochlin. Rebbi Yochanan answered that he understands that the Mishnah is a minority opinion, as is clearly implied by a Beraisa.

Reish Lakish's initial question is difficult to understand. The Halachah normally follows the statement of a "Stam Mishnah" (an anonymous Mishnah in which the opinion expressed is not disputed). Since the Mishnah here is a Stam Mishnah, why did Reish Lakish ask his question in the first place, when the Mishnah explicitly states that the skin of the head of a tender calf is considered like flesh?

(a) TOSFOS (DH Or ha'Rosh) answers that although the Halachah usually follows a Stam Mishnah, Reish Lakish was presented with an actual, practical question involving the skin of a young calf and he needed to know whether the Halachah in practice follows the Stam Mishnah.

The LEV ARYEH and TIFERES YAKOV are not satisfied with this answer. Rebbi Yochanan himself says in many places that the Halachah always follows the Stam Mishnah. Why, then, would Reish Lakish -- who certainly knew that Rebbi Yochanan ruled this way -- have reason to assume that Rebbi Yochanan would tell him otherwise in this case?

(b) The TOSFOS HA'ROSH gives a second answer. He explains that Reish Lakish knew the Beraisa that Rebbi Yochanan later quoted. Since there was a minority opinion in the Beraisa that matched the view of the Stam Mishnah here, Reish Lakish was in doubt about whether he should rule like the Stam Mishnah. Rebbi Yochanan answered him that his concern was justified, for these opinions indeed are the same opinion, and therefore the Halachah does not follow this opinion. (See Tosfos ha'Rosh at length.)

(c) The LEV ARYEH answers that Reish Lakish was unsure of Rebbi Yochanan's definition of a "young calf." The Gemara earlier discusses a doubt about whether Rebbi Yochanan maintained that even after a calf is one year old it is considered "young" as long as it is nursing, or whether he maintained that only when a calf is under one year old and nursing is it considered young. Reish Lakish, therefore, asked Rebbi Yochanan what kind of young calf is Tamei. Rebbi Yochanan answered that, practically, it is never Metamei Tum'as Ochlin. This prompted Reish Lakish to ask from the Stam Mishnah, and Rebbi Yochanan answered that although it is a Stam Mishnah, the Halachah does not follow its view, since it is the view of a minority opinion.

(d) The TIFERES YAKOV prefaces his answer by saying (like the Tosfos ha'Rosh) that Reish Lakish knew the Beraisa which Rebbi Yochanan quoted, and he based his question on its words. The Beraisa opens with the Tana Kama's statement that the skin under the Alyah (the fat of the tail) can become Pigul. Elazar ben Yehudah and Rebbi Shimon ben Yehudah state that the skin of the hooves, the skin of the head of a young calf, the skin under the Alyah, and all skin that the Chachamim listed regarding Tum'ah as being considered like the meat of the animal are subject to Pigul. In what way do they argue with the Tana Kama?

On a basic level, it seems that the Tana Kama does not agree that this is a rule that can be applied to Pigul the same way that it applies to Tum'ah, while Elazar ben Yehudah and Rebbi Shimon ben Yehudah maintain that it applies to Pigul just as it applies to Tum'ah.

However, the statement of Elazar ben Yehudah and Rebbi Shimon ben Yehudah needs clarification. They single out these three cases -- the skin of the hooves, the skin of the head of a young calf, and the skin under the Alyah. Why do they mention specifically these cases? Although the Tana Kama agrees with regard to the skin under the Alyah, it seems that they mention the other cases to show that, unlike the Tana Kama, these also can become Pigul. Reish Lakish was in doubt about whether the Tana Kama in the Beraisa argues not only that the skin of the head of the young calf cannot become Pigul, but also that it does not even become Tamei with Tum'as Ochlin. Reish Lakish therefore asked if the Tana Kama maintains that the skin of the head becomes Tamei with Tum'as Ochlin. When Rebbi Yochanan answered that it does not, Reish Lakish said that this is not the answer that one would have expected, because the Stam Mishnah says that it is Metamei Tum'as Ochlin. Accordingly, this should also be the view of the Tana Kama of the Beraisa! Rebbi Yochanan answered that the Mishnah follows the second opinion of the Beraisa, and therefore the Halachah does not follow the Stam Mishnah. (Y. MONTROSE)

OPINIONS: Rebbi Avahu in the name of Reish Lakish teaches that for "Gabal, Tefilah, and Netilas Yadayim," one must travel up to four Mil. To what does "Tefilah" refer?

(a) RASHI (DH ul'Tefilah, and as quoted by TOSFOS DH l'Gabal) writes that this refers to one who is traveling and has decided to stop at an inn to rest. He must continue to travel up to four Mil in order to find a synagogue in which to pray with a Minyan.

(b) The ARUCH explains that this means that one must travel up to four Mil in order to find water for washing the hands before Tefilah, in accordance with the requirement to wash before prayer (Berachos 15a; Shulchan Aruch OC 92:4). (See, however, TOSFOS here, DH l'Gabal, and in Berachos 15a, DH a'Man, who argues with the Aruch's explanation based on his Girsa of the Gemara in Berachos 15a.)

(c) RABEINU CHANANEL explains that this means that one must travel up to four Mil in order to find a Mikvah in which to immerse himself, in accordance with the requirement for someone who is Tamei with Tum'as Keri to immerse in a Mikvah before Tefilah (Berachos 22a, Shulchan Aruch OC 88:1, 240:1).