1) THE FORMATION OF MOUNTAINS
In the Mishnah (21a), Rebbi Meir says that if a woman miscarries something resembling an animal, she is Tamei with Tum'as Yoledes. Rebbi Chiya bar Aba in the name of Rebbi Yochanan explains that Rebbi Meir derives from a Gezeirah Shavah ("va'Yitzer," written both with regard to the formation of man and with regard to the formation of animals) that just as a woman becomes Tamei with Tum'as Yoledes when she gives birth to a human child, a woman also becomes Tamei with Tum'as Yoledes when she gives birth to a form that resembles an animal.
Rebbi Ami asks that according to this reasoning, Rebbi Meir also should rule that a woman is Tamei with Tum'as Yoledes when she miscarries the form of a mountain, because the term Yetzirah is also used with regard to the creation of mountains (in Amos 4:13). Rebbi Chiya answers that a woman is not large enough to give birth to a mountain.
The MAHARATZ CHAYOS points out that the Yerushalmi here answers Rebbi Ami's question differently. The word "Yetzirah" is not used in the original creation of mountains; it appears only in a verse in Amos, not in Bereishis, and therefore it is not used for a Gezeirah Shavah.
The Maharatz Chayos explains this answer as follows. The Yerushalmi means that at the time of the creation of the world, mountains were not created. After the first six days of creation, the topography of the world was level; there were no mountains. Only after many years of persistent storm winds, floods, and geological activity were the mountains and hills formed. The Yetzirah of mountains cannot be compared to the Yetzirah of man and animal, since mountains were formed only as a result of the laws of nature which Hash-m established in the world He created.
2) MAKING REBBI ZEIRA LAUGH
QUESTION: Rebbi Yirmeyah asked Rebbi Zeira a question about a very unusual case. He asked that according to Rebbi Meir, who says that a woman who miscarries a form that resembles an animal is Tamei with Tum'as Yoledes as if she gave birth to a human, what is the law in a case in which one gives money to the father of such a creature in order to be Mekadesh the creature during the pregnancy? May he marry the animal's sister afterwards?
Rav Acha bar Yakov explained that Rebbi Yirmeyah was merely trying to get Rebbi Zeira to laugh, but he did not succeed.
What was Rebbi Yirmeyah's motivation for trying to amuse Rebbi Zeira and make him laugh, and why indeed did Rebbi Zeira not laugh?
ANSWERS:
(a) RASHI (DH li'Yedei Gichuch) says that "in all of these tricks," Rebbi Yirmeyah tried to get Rebbi Zeira to laugh, but he would not laugh because it is forbidden to fill one's mouth with laughter in this world (Berachos 31a), and Rebbi Zeira observed was very stringent in his observance of this precept.
Rashi's words are difficult to understand. Why does Rashi say "in all of these tricks," when the Gemara here records only one amusing question that Rebbi Yirmeyah asked?
The answer to this question may be that the Gemara in a number of places relates that Rebbi Yirmeyah asked lighthearted questions in order to enliven Rebbi Zeira's mood. Rashi, when he says "in all of these tricks," is referring to all of the places throughout the Gemara that discuss such attempts of Rebbi Yirmeyah to make Rebbi Zeira laugh. The MAHARATZ CHAYOS here adds that it is possible that many of the unusual questions throughout the Gemara that Rebbi Yirmeyah posed to Rebbi Zeira can be attributed to Rebbi Yirmeyah's desire for Rebbi Zeira to laugh. (Indeed, Rebbi Yirmeyah was even expelled from the Beis Midrash for asking an odd question (Bava Basra 23b), and he was invited back only after he reasserted his wisdom (Bava Basra 165b).)
In a similar vein, the CHAVOS YA'IR (#152, cited at the end of SEFER CHAFETZ CHAYIM) suggests that Rebbi Zeira and Rebbi Yirmeyah had different paths in Avodas Hash-m. They continually debated whether abstinence is commendable or forbidden.
Rebbi Zeira understood that fasting and self-affliction is the correct way to achieve holiness. Indeed, he would fast for long periods, and he would test himself with all kinds of self-afflictions to test his total devotion to Hash-m (Bava Metzia, end of 85a).
Rebbi Yirmeyah, on the other hand, maintained that a person may not afflict himself beyond what the Torah requires, consistent with the view of those who maintain that a Nazir is called a "Chotei," a sinner (Nedarim 10a). Rebbi Yirmeyah, following his path in Avodas Hash-m, tried to lighten Rebbi Zeira's somberness because he believed that it was an incorrect path in Avodas Hash-m.
However, the Maharatz Chayos is left with another question on Rashi. Rashi concludes by saying that it is forbidden to fill one's mouth with laughter, and that Rebbi Zeira was very stringent. If it indeed is forbidden, then why does Rashi say that Rebbi Zeira was stringent? He was merely following the Halachah! Moreover, Rebbi Yirmeyah presumably knew this Halachah (taught by Rebbi Shimon bar Yochai in Berachos 31a). Why, then, did he want to cause Rebbi Zeira to transgress by making him laugh?
(b) The ARUCH LA'NER explains that Rebbi Yirmeyah and Rebbi Zeira agreed that one should not fill one's mouth with laughter in this world. However, they disagreed about whether one may fill his mouth with laughter while learning Torah. Rebbi Yirmeyah maintained that since the verse states, "Ivdu Es Hash-m b'Simchah" -- "Serve Hash-m with happiness" (Tehilim 100:2), one is permitted to express happiness while learning Torah, even if it involves humor and laughter. The Aruch la'Ner points out that such an approach is mentioned in the Zohar, as well as by the RIF in the EIN YAKOV to Berachos. The Aruch la'Ner explains that this is what Rashi means when he says that Rebbi Zeira was very stringent. Although Rebbi Zeira understood Rebbi Yirmeyah's point of view, Rebbi Zeira was stringent and refrained from laughing even when it is permitted.
The approach of the Aruch la'Ner sheds light on a perplexing Gemara in Megilah (7b). The Gemara there relates that Rebbi Zeira and Rabah were having a Purim feast together, when Rabah arose and "slaughtered" Rebbi Zeira and then revived him. All of the commentators have difficulty with understanding "slaughtered" literally, for it is not reasonable to suggest that a great Amora would kill his colleague. The YA'AVETZ there explains that Rabah saw that the festivities in his home on Purim were becoming too joyous, and he wanted to calm the excitement. He made it look as though he was taking a knife and slaughtering Rebbi Zeira, so that everyone would become more serious. Rebbi Zeira, who thought that Rabah really intended to kill him, fainted from shock. He might have passed away from the shock had Rabah not prayed for him and revived him. (M. KORNFELD)
We may add that Rebbi Zeira was so taken aback by what Rabah did, because throughout his entire life Rebbi Zeira aspired to avoid laughter. When he realized that Rabah did this in order to rebuke him for being lightheaded, he was shocked at himself for behaving in a way that was counter to his own Midah. This made "his heart die inside of him," until Rabah revived him (-Y. MONTROSE). (See also Insights to Berachos 30:2, Shabbos 33:2, Megilah 7:2, and Bava Metzia 85:2.)

23b----------------------------------------23b

3) THE TYPE OF PERSON THAT IS PERMITTED TO BE EATEN
QUESTION: In the Mishnah (21a), Rebbi Meir says that if a woman miscarries something resembling an animal, she is Tamei with Tum'as Yoledes. Rav Ada bar Ahavah asked Abaye, what is the Halachah, according to Rebbi Meir, in a case in which a human-like creature is found in a pregnant animal? May we eat that creature just as we may eat an animal?
The Gemara suggests an answer based on the words of Rebbi Yochanan. Rebbi Yochanan ruled that if one finds a pregnant animal carrying a dove-like creature, he is not permitted to eat that creature. Similarly, the person-like creature found inside of an animal should not be permitted. The Gemara rejects this proof, arguing that a dove-like creature cannot be compared to a human-like creature. A dove has neither "Parsos" nor "Parsah," while a human has "Parsah" even though he has no "Parsos."
What is the meaning of the Gemara's refutation of the proof from Rebbi Yochanan, and what does the Gemara conclude with regard to the status of a human-like creature found inside of an animal?
ANSWER: RASHI (DH Of and DH Parsah) explains that the Torah permits a fetus found inside of a Kosher animal as long as it has Parsos (hooves), even if its Parsos are not split. The feet of a bird, however, are not considered Parsos at all, while human feet may be considered to be Parsos (but merely unsplit, or "Parsah"). Although a person does not have split feet, he does have a heel which corresponds to the hoof of an animal. Since the Torah permits eating a fetus found inside of a Kosher animal even though the fetus does not have split hooves, it also should permit eating the humanoid found inside of a Kosher animal, since this creature has a heel.
Does Rashi mean that the humanoid must physically possess a heel in order to be permitted, or that it suffices that it looks like a human, who normally has a heel?
1. The RAN in Chulin (69a) quotes an opinion that maintains that Rebbi Yochanan's reason for prohibiting a dove found inside an animal is that it does not physically possess hooves. If it physically possesses a hoof (even though such an appendage is a mutation on a bird), its status is a Safek, like the status of the human-like creature found inside of an animal (since the Gemara does not answer its question about such a fetus). According to this opinion, even if an animal-like creature is found inside of an animal (such as calf found inside of a cow) which does not physically possess hooves (for example, it has no legs), it would be forbidden. On the other hand, a dove-like creature, found inside a pregnant cow, which happens to have hooves, would be the same Safek as a human-like creature, for its status depends on whether it actually has hooves or not.
2. The Ran himself quotes TOSFOS as saying that it does not matter whether or not the creature actually has hooves. What matters is whether the species that it resembles normally has hooves. Accordingly, the Gemara says that a human-like creature may be permitted to be eaten when found in an animal, since it normally has a heel, which qualifies as a "Parsah." A dove-like creature may not be eaten, because doves normally do not have hooves. (Y. MONTROSE)

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