1) THE TWO POINTS OF DISPUTE BETWEEN REBBI YOSI AND REBBI MEIR
QUESTION: Rava explains that Rebbi Yosi and Rebbi Meir disagree about two points. They disagree about the Halachah in a case in which an Ohel the size of a Tefach transfers Tum'ah to the threshold. One Tana maintains that the entire threshold is considered "inside" the house (and Tum'ah spreads to the house), and the other Tana maintains that only part of the threshold is considered inside the house -- the part that is inside the house when the door is closed. They also disagree about what comprises a "Chalal Tefach" -- a hollow passageway such as the throat, or even a solid passageway, such as the entire width of the neck.
Why does Rava say that Rebbi Yosi and Rebbi Meir disagree about both Halachos? They clearly disagree about the threshold, since Rebbi Yosi explicitly mentions the place where the door closes. However, there is no indication that they also disagree about whether the solid part of the neck is included in the Tefach.
ANSWER: TOSFOS (DH Amar) explains that Rebbi Yosi uses the term "Ro'im" ("we look"). This implies that there is something that requires examination and is not clearly visible, such as Tum'ah which is inside of a dog's stomach, or the size of the passageway of the dog's throat. If Rebbi Meir and Rebbi Yosi disagree only in the case of a Tefach-thick neck that transfers Tum'ah to a threshold, the only thing we need to know is the extent to which the neck of the dog stretches (at the point where the door closes). However, since this can be easily determined, the term "Ro'im" is not appropriate. The word "Ro'im" implies that Rebbi Yosi argues with Rebbi Meir on a point that involves a closer examination.
2) WHY WOULD "TUM'AH" WHICH IS ON THE THRESHOLD NOT BE "METAMEI" THE HOUSE?
QUESTION: Rebbi Yosi maintains that Tum'ah that is on the threshold of a house can be Metamei the house only when it is within the point at which the door closes.
Why, though, should the house not be Tamei even when the Tum'ah is outside of the point at which the door closes? When the door is open, the Tum'ah is under the lintel; the lintel is an Ohel and should transfer the Tum'ah to the house!
ANSWER: TOSFOS (DH Anan) answers that Rebbi Yosi is discussing a situation in which the part of the threshold that remains outside after the door is closed is less then a Tefach wide. Since the closed door separates that part of the lintel from the rest of the house, the lintel does not constitute an Ohel because it is less than a Tefach wide, and thus it cannot transfer Tum'ah.
3) THE TANA WHO ARGUES WITH REBBI YOSI
QUESTION: Rebbi Yosi maintains that Tum'as Ohel can be Metamei through Maga. The Gemara here asks who is the Tana who argues with Rebbi Yosi and maintains that Tum'as Ohel and Tum'as Maga do not combine to be Metamei.
RASHI (DH Man Tana) explains that the Gemara is asking who is the Tana of the Mishnah in Ohalos (3:1) quoted earlier (125a-b) who says that Tum'as Ohel does not combine with Tum'as Maga to be Metamei.
Why does Rashi assume that Rebbi Yosi must be arguing with the Tana of that Mishnah? The Mishnah there discusses the specific case of one who touches a half-k'Zayis of Tum'ah while he is standing under one roof together with another half-k'Zayis of Tum'ah. Perhaps Rebbi Yosi agrees that in that case the Tum'as Ohel does not combine with the Tum'as Maga (and the person remains Tahor), because, as Abaye (125b) says, in that case the Ohel is more than a Tefach above the Tum'ah (and such Tum'as Ohel is not considered Maga), or because, as Rava (125b) says, an Ohel which effectively draws Tum'ah from one place to another with one ceiling is not the same form of Tum'ah as Maga! (TOSFOS DH Man)
ANSWERS:
(a) TOSFOS disagrees with Rashi's explanation. He explains that the Gemara does not assume that the Tana of the Mishnah in Ohalos argues with Rebbi Yosi. Rather, the Gemara is inferring that there is a Tana who argues with Rebbi Yosi from the fact that the Gemara earlier (125b) says, "Rebbi Yosi maintains that Ohel is a form of Maga." This implies that there are others who do not consider it a form of Maga. The Gemara is asking who those other Tana'im are.
(b) Perhaps Rashi understands the question of the Gemara as follows. The Gemara infers from the Mishnah in Ohalos that even when the Ohel is less than a Tefach high (according to Abaye), or the Tum'ah is not drawn from place to place by the Ohel (according to Rava), it still would not be Metamei with Tum'as Maga. This is because the first part of that Mishnah (according to Rebbi Zeira) says that only an Ohel that shelters an object of Tum'ah that is between two chests ("Tum'ah Retzutzah") is like Maga, implying that all other cases of Ohel are not like Maga. (Tosfos himself notes this inference earlier; see Tosfos to 125b, DH Amar.) (M. KORNFELD)

126b----------------------------------------126b

4) A BONE THE SIZE OF A BARLEY GRAIN
QUESTION: The Gemara quotes the Beraisa in which Rebbi Shimon says that there are three types of Tum'ah of Mes that are Metamei in two ways out of the three ways that Tum'ah can be transferred -- Ohel, Maga, and Masa. One of these types of Tum'ah is the Tum'ah of an "Etzem k'Se'orah," a human bone the size of a barley grain, which is Metamei through Maga and Masa, but not through Ohel. What is the source that an Etzem k'Se'orah is not Metamei through Ohel?
ANSWER: RASHI (DH Etzem k'Se'orah) explains that this law is a Halachah l'Moshe mi'Sinai.
TOSFOS (DH Etzem k'Se'orah) disagrees with Rashi's explanation, because the Gemara in Nazir (53b) explicitly derives the Tum'ah of an Etzem k'Se'orah from verses in the Torah. Tosfos, however, does not offer an alternative source for the law that an Etzem k'Se'orah is not Metamei through Ohel.
The TIFERES YAKOV has difficulty with the statement of Tosfos. The verses cited by the Gemara in Nazir do not actually teach that a bone the size of a barley grain is Metamei. The Gemara in Nazir does derive some laws regarding the Tum'ah of bones from verses. It quotes the verse, "v'Chol Asher Yiga Al Penei ha'Sadeh... O v'Etzem Adam" -- "And whoever touches one who was slain with a sword in the open fields, or a dead body, or a bone of a man... shall be Tamei for seven days" (Bamidbar 19:16), from which the Gemara derives that a measurement of one-quarter of a Kav (Rova ha'Kav) of bones is needed in order to be Metamei through Ohel (as opposed to the smaller measurement of a grain of barley). Similarly, the Gemara in Nazir (54a) derives from the verse, "v'Al ha'Noge'a ba'Etzem" -- "... and upon the one who touched a bone" (Bamidbar 19:18), that a bone is Metamei through Maga when it is the size of a barley grain. However, there is no mention or hint in the verses to the Shi'ur of a quarter of a Kav or the Shi'ur of a barley grain. It must be that the Gemara simply is applying Halachos l'Moshe mi'Sinai (that teach these Shi'urim) and inserting them into the context of the verses. Why, then, does Tosfos say that these amounts and Halachos are derived from the verses and are not learned from a Halachah l'Moshe mi'Sinai? In fact, Tosfos in Nazir (53b, DH O v'Etzem Adam) explicitly agrees with the words of Rashi here and says that these amounts are Halachos l'Moshe mi'Sinai, and the verse is merely an Asmachta.
The LEV ARYEH initially agrees with Tosfos' question on Rashi, and he adds that Tosfos' source is a statement of Rebbi Yochanan in Nazir (54a). The Gemara there quotes a Beraisa that says that the verse, "O va'Mes" -- "or [touched] a dead person" (Bamidbar ibid.), teaches that a limb of a dead person is Metamei. The verse there is discussing Tum'as Maga. Rebbi Yochanan understands that the verse is discussing a case in which the limb has a piece of bone in it the size of a barley grain. According to Rebbi Yochanan, that verse is not needed to teach that the limb is Metamei through Maga, because we already know that a bone the size of a barley is Metamei through Maga. Rebbi Yochanan therefore says that the verse is teaching (through the principle of "Im Eino Inyan") that a bone the size of a barley grain is Metamei through Masa. Since we rule like Rebbi Yochanan, we have a source in the verse that a bone the size of a barley grain is Metamei through Maga and Masa, while the earlier Derashah in the Gemara there teaches that only a bone the size of a Rova ha'Kav is Metamei through Ohel.
However, the Lev Aryeh points out that another Gemara strongly implies that there is no source in the verse that an Etzem k'Se'orah is not Metamei through Ohel. The Gemara derives in a number of places (see, for example, Sukah 5b-6a) from the verse, "Eretz Chitah u'Se'orah..." (Devarim 8:8, which lists the seven species of fruits of Eretz Yisrael), many of the Shi'urim in Halachah. From the word "barley" in the verse, the Gemara derives that a bone the size of a barley grain is Metamei through Maga and Masa, but not through Ohel. The Gemara asks that it says nowhere in the verse that these amounts are specifically for these topics to which the Gemara ascribes them. The Gemara concludes that the verse is merely an Asmachta, and the Shi'urim are known from a Halachah l'Moshe mi'Sinai. This clearly supports the words of Rashi here. Therefore, the Lev Aryeh concludes that Rashi's explanation is correct. (Y. MONTROSE)
5) THE HALF-MOUSE
OPINIONS: The Mishnah here mentions a mouse "which is half-flesh and half-earth; one who touches the flesh part is Tamei, and one who touches the earth part is Tahor."
This creature is mentioned elsewhere in the Gemara in a different context. The Gemara in Sanhedrin (91a; see Insights there) relates that a certain heretic challenged Rebbi Ami about the possibility of Techiyas ha'Mesim. He argued that it is not possible for a decomposed body, which turns into earth, to rise again as a living body. One of Rebbi Ami's proofs for Techiyas ha'Mesim was the fact that there exists a rodent that lives in the valley "that today is half-flesh and half-earth, and tomorrow it becomes completely flesh."
According to modern scientific knowledge of the biological world, all living things come about through propagation and regeneration. However, in the times of the Chachamim, it was the accepted common belief that many creatures are formed from inanimate objects. The Gemara in Shabbos (107b) permits killing on Shabbos a louse that is produced from sweat spontaneously (see TOSFOS to Shabbos 12a). The SHULCHAN ARUCH (YD 84:15) prohibits eating birds that grow on trees because of the Isur of Sheretz. It was also commonly believed that flies are produced from rotting meat. (It was only towards the end of the seventeenth century (CE) that scientific experimentation (by Francesco Redi and Louis Pasteur) proved that substances that were protected from the air did not produce insects.) The reason why Rebbi Ami proves his point from the rodent is that the rodent arises not from a living organism, but from dirt, like the dead who will come to life.
Is there any evidence today to support the existence of rodents that are formed from the earth?
(a) The RAMBAM seems to confirm the existence of such a creature. In Perush ha'Mishnayos here he writes, "This is a well-known matter; there is no end to the number of people who have told me that they have seen it. Such a thing is indeed astonishing, and I have no explanation for it."
The TIFERES YISRAEL (Bo'az, Chulin 9:6) also defends the existence of such a creature. He writes, "I have heard heretics mocking with regard to the creature that is discussed here and in Sanhedrin 91a, and denying it, saying that there is no such thing at all. Therefore, I have seen fit to mention here that which I found written in a Western European work compiled by a scholar renowned among the scholars of the world. His name is Link, and the book is titled 'Auervelt.' In volume I, page 327, he writes that such a creature was found in Egypt in the district of Thebes, and in the Egyptian language that rodent is called 'dipus jaculus'; and in German it is called 'springmaus.' Its forequarters -- head, chest, and hands -- are perfectly formed, but its hindquarters are still embedded in the earth, until after several days when it fully changes to flesh. And I say, 'How great are Your works, Hash-m!'"
(The "springmaus" is the jerboa. The jerboa belongs to a family of rodents that have very small forelegs (which they hold against their bodies) and long back legs for jumping and digging burrows in which they sleep. This is the dipus jaculus mentioned by Link.)
(b) Rav Aryeh Carmell suggests that the creature referred to is simply a mole. A dead mole, with clods of earth attached to its body, would appear to have grown from the ground. Alternatively, as it emerges from the earth, people could mistakenly believe that it is growing from the earth. (However, the people in the time of the Gemara seem to have been familiar with moles and burrowing creatures, and thus people would not have been mistaken about the nature of such a creature; see Moed Katan 6b.)
Similarly, perhaps the Gemara refers to the existence of certain species of small amphibians and rodents that burrow in the mud and entomb themselves in a cocoon of solidified mud during the dry season. Entombed, the creatures' bodily functions nearly cease and they remain entirely motionless until the first rain, at which point they shed their cocoon. A creature photographed in such a state unquestionably appears as a clod of earth, and while leaving its cocoon it certainly looks as though it is half-earth and half-creature. One such animal is the burrowing frog, which lives in arid regions and deserts. At the start of a long dry spell, when the pools from the last rainstorms are in the last stages of evaporation, the frog buries itself up to twelve inches deep in the mud. There it settles into a state of suspended animation, with its breathing and heartbeat slowing to a rate just sufficient to keep it alive. After about two weeks, the outer layers of the frog's skin detach and bond into a membrane that is fully waterproof, apart from two tiny tubes to the frog's nostrils. The frog can survive in this state amidst desert drought for many years. Then, when the rainfall finally comes and turns the sand into mud, the frog breaks out if its bag and emerges upon the surface, appearing to have grown from the mud.
If this is indeed the case, such a creature is the prime proof for Techiyas ha'Mesim. It first entered a state of suspended animation that can be likened to death -- in fact, it might even be considered inanimate, according to Halachah, while in that state -- and then it was "revived" and "returned to life." Even if the Chachamim were aware of the true circumstances surrounding this creature, they would have cited it as a proof for Techiyas ha'Mesim, and discussed its status regarding Tum'ah and Taharah. (M. KORNFELD)
(c) RAV SAMSON RAPHAEL HIRSCH has an enlightening approach to the subject of how to understand statements like these in the Gemara in light of modern science. In his essay entitled, "Trusting the Torah's Sages" (a letter written in 1876 to Rav Pinchas M. E. Wechsler, published in 1976 in the Jerusalem journal Hama'ayan, Chapter 4), Rav Hirsch explains that the Chachamim were simply giving a ruling for a case that was presented to them. They did not take it upon themselves to verify whether or not such creatures existed.
The same is true with regard to the proof to Techiyas ha'Mesim that the Gemara cites. The fact that the people who lived at the times of the Amora'im had no trouble accepting the fact that an animal can form from a clod of earth, served as a perfect way for the Amora'im to prove to their contemporaries that Techiyas ha'Mesim is not a stretch of the imagination.
6) "GOLEL" AND "DOFEK"
OPINIONS: The Gemara quotes the Beraisa in which Rebbi Shimon says that there are three types of Tum'ah of Mes that are Metamei in two ways out of the three ways that Tum'ah can be transferred -- Ohel, Maga, and Masa. One of these types of Tum'ah is the Tum'ah of "Golel" and "Dofek" (see Background to the Daf) which are Metamei through Ohel and Maga, but not through Masa. What is the source that Golel and Dofek are not Metamei through Masa?
ANSWERS:
(a) RASHI (DH Golel) explains that according to the view that the Tum'os of Golel and Dofek are Halachos l'Moshe mi'Sinai, the law that the Tum'ah is not transferred through Masa is also a Halachah l'Moshe mi'Sinai.
However, Rashi gives no source for why they are not Metamei through Masa according to the view that derives the laws of Golel and Dofek from verses in the Torah.
(b) TOSFOS (DH Golel) explains that in order for a Tum'ah to be transferred through any means (such as Ohel, Maga, or Masa), there must be a source in the Torah for that form of transferal of Tum'ah. Accordingly, the verse "v'Chol Asher Yiga Al Penei ha'Sadeh" (Bamidbar 19:16) teaches that Golel and Dofek are Metamei through Ohel, and the word "Yiga" teaches that they are Metamei through Maga. Since there is no source in the Torah for Tum'as Masa of Golel and Dofek, they are not Metamei through Masa.
(c) Perhaps one may suggest a logical source for the lack of Tum'as Masa of Golel and Dofek. The Tum'ah of Golel is directly related to its location (as a coffin-cover, grave-marker, or vault-stopper, as described in Background to the Daf). When it is even slightly moved ("Masa") it no longer serves the purpose of a Golel, and thus it is not Metamei until it is replaced. (The Tosefta mentions an opinion that a Golel that is moved from its original place is Tahor.) (M. KORNFELD)
7) THE "TUM'AH" OF THE EGGS OF "SHERATZIM"
QUESTION: The Gemara derives from the verse, "ha'Sharetz" (Vayikra 11:31), that once a Sheretz has begun to form in its egg, it is Metamei.
However, the Gemara earlier (64a) assumes that one is liable for eating a Sheretz from the point at which the Sheretz starts to form in its egg. The Gemara there understands that this is obvious, and no verse is necessary to prove it. Why, then, does the Gemara here need a verse to prove that a Sheretz is Metamei from the time that it begins to form in the egg? (TOSFOS DH Yachol)
ANSWERS:
(a) TOSFOS explains that with regard to the prohibition against eating a Sheretz, a Sheretz becomes prohibited from the moment that it can be defined as a "Sheretz," which is the moment that it begins to form in its egg. In contrast, one might have thought that in order to be Metamei, the Sheretz not only must be identifiable as a Sheretz, it must also be identifiable as a specific type of Sheretz, such as an Achbar. When a Sheretz begins to form, it is identifiable as a Sheretz, but it cannot yet be called an Achbar. Therefore, it is necessary for the verse to teach that such a Sheretz nevertheless is Metamei.
(b) Tosfos answers further that the verse regarding the ability of a Sheretz to be Metamei in its egg is the source that the prohibition against eating a Sheretz applies from that moment as well. (Z. Wainstein)

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