1) ONE WHO THINKS THAT IT IS PERMITTED TO BE "MEVATEL ISUR L'CHATCHILAH"
QUESTIONS: Abaye (end of 22a) attempts to prove to Rav Dimi that Tum'ah that has become Batel cannot be revived. He quotes the Mishnah in Terumos (5:2) that discusses a case of one Se'ah of Terumah that is Tamei that falls into one hundred Se'ah of Chulin that is Tahor. Rebbi Eliezer maintains that one must remove one Se'ah from the mixture and leave it to rot, because we say that the one that fell in is the one that is removed. The Gemara (23a) asks what is the status of the remaining produce, according to Rebbi Eliezer. The Gemara answers that the remaining produce must be eaten dry, parched, kneaded with fruit juice, or divided into small pieces of dough (with less than the size of a k'Beitzah in one place). All of these possibilities do not allow the Chulin to become Huchshar for Tum'ah, and thus the Chulin cannot become Tamei from the piece of Terumah Teme'ah.
Ula explains that the reason why the remaining one hundred Se'ah of Chulin are not considered to be entirely Chulin once one Se'ah is removed (which, according to Rebbi Eliezer, is presumed to be the Se'ah of Terumah that fell in) is because of a Gezeirah. If we would permit the remaining Chulin, one might bring a Kav of Chulin that is Tamei and mix it with slightly more than a Kav of the Chulin that was in the mixture with the Terumah, with intention that the majority of Tahor produce be Mevatel the Tamei produce. This would be ineffective, because, in Rebbi Eliezer's mixture, there is one part of Terumah Teme'ah in one hundred parts of Chulin, and when the Kav of Chulin that is Tamei combines with the slightly more than a Kav of Chulin of Rebbi Eliezer's mixture, the original Tum'ah that became Batel will be revived and combine with the Kav of Chulin that is Tamei, making the contents of the mixture be half-Tamei and half-Tahor, effectively rendering the entire mixture Tamei (see RASHI DH Gezeirah).
TOSFOS (DH Savar) asks why are we concerned that a person will think that he may place a Kav of Chulin that is Tamei into slightly more than a Kav that is Tahor? The Gemara in Beitzah (4b) clearly states that it is forbidden to be Mevatel an Isur l'Chatchilah -- it is forbidden to add permitted objects into forbidden ones in order to be Mevatel the Isur! Moreover, the Gemara in Gitin (54b) cites an opinion that even if one inadvertently (b'Shogeg) adds Heter to Isur, the Isur does not become Batel, even b'Di'eved. Tosfos concludes that the Gemara here must be following the opinion in Gitin that maintains that, b'Di'eved, the Isur does become Batel, and that the Gemara here is discussing a case of "Omer Mutar," mistakenly thinking that a certain prohibited act is permitted, and that such a case is considered like a case of Shogeg.
(a) Why does Tosfos assume that "Omer Mutar" is considered like Shogeg? Rava in Makos (7b) maintains that one who thinks that it is permissible to murder ("Omer Mutar") is considered to be like "Mezid," and not like "Shogeg"! (See RAMBAM, Hilchos Retzichah 6:10, who rules in accordance with Rava's opinion.)
(b) The TAZ (YD 99:9) cites the words of Tosfos as proof that even according to the opinion in Gitin that the Rabanan penalized one who is Mevatel an Isur even inadvertently, they did not penalize one who does so thinking that it is permitted ("Omer Mutar"). In such a case, everyone agrees that b'Di'eved the mixture is permitted.
How do the words of Tosfos prove this? Tosfos says merely that "Omer Mutar" is considered like Shogeg according to the opinion in Gitin that maintains that the Rabanan did not penalize one who inadvertently is Mevatel an Isur!
(a) The CHASAM SOFER (Teshuvos, YD #88, DH Rishon) answers that a distinction must be made between "Omer Mutar" with regard to murder, and "Omer Mutar" with regard to other transgressions. One who thinks that murder is permitted clearly is acting negligently and maliciously; murder is very severe and it is not reasonable that a person should make such a grave mistake as to think that it is permitted. In contrast, other Isurim -- such as eating food that is Tamei -- are not regarded to be as severe as murder, and thus it is feasible that one would mistakenly think that it is permitted. Accordingly, a case of "Omer Mutar" may be considered even less severe than a case of Shogeg.
(b) The Chasam Sofer answers that the Taz either possessed a different text of Tosfos that the text that we have, or he simply understood that Tosfos' intention is to say that "Omer Mutar" is considered an even lighter form of transgression than Shogeg, and, accordingly, even according to the opinion that penalizes the person in a normal case of Shogeg, we are more lenient with regard to a case of "Omer Mutar." (D. BLOOM)
2) HALACHAH: AN ANIMAL THAT IS NURSING A CALF
QUESTION: In the Mishnah, Raban Shimon ben Gamliel states that when one buys an animal from a Nochri and finds that it is nursing a calf, we do not suspect that the calf is the offspring of another cow. Rather, we assume that the young calf is the offspring of the nursing mother, and any subsequent birth is not subject to the laws of Bechor.
Earlier (20b), Rebbi Akiva states that most animals do not have milk unless they have already given birth. What, then, is Raban Shimon ben Gamliel adding here with his statement? From the words of Rebbi Akiva we learn that we treat a nursing animal as one that has already given birth!
In addition, why does Rav tell us that the Halachah follows Raban Shimon ben Gamliel, when we already know that the Halachah follows Rebbi Akiva?
(a) The ROSH (3:2) quotes RABEINU TAM who explains that from the fact that the Gemara quotes Rav who finds it necessary to state that the Halachah follows Raban Shimon ben Gamliel, it must be that we do not rule like Rebbi Akiva. This implies that Raban Shimon ben Gamliel and Rebbi Akiva are arguing. What, though, is their argument?
Raban Shimon ben Gamliel maintains that nursing a calf is a sign that a cow has already given birth, but the presence of milk alone does not serve as proof that it has given birth. Rebbi Akiva argues and maintains that the presence of milk alone suffices to prove that the cow has given birth in the past.
(b) The RAMBAN suggests that the Halachah does follow Rebbi Akiva. Raban Shimon ben Gamliel is adding to Rebbi Akiva's ruling and saying that when we find an animal that has milk but we do not know of any calf that it has borne, when, after some time passes, we see it nursing a calf, we may assume with certainty that the calf is its own offspring, and the next birth is exempt from Bechorah (because an animal would not nurse a calf unless it had given birth).
HALACHAH: The RAMBAM (Hilchos Bechoros 4:8) rules that when we see an animal nursing a calf, or when we see that an animal has milk, we assume that the next calf born is not a Bechor.
With regard to the prohibition of killing a mother animal and its offspring on the same day, the SHULCHAN ARUCH (YD 16:5) rules that when a calf persistently follows a cow, we may assume that it is following its mother, and it is forbidden to slaughter the two of them on the same day. The KEREISI U'PLEISI adds that since there still exists a slight doubt whether the cow is indeed the mother, one who transgresses and slaughters them on the same day does not receive Malkus.
3) HE SAID IT WHILE HE WAS SLEEPING
QUESTION: When Rav Sheshes heard Rav's ruling, he responded by saying, "When Rav was napping and falling asleep he said this teaching!"
How could Rav Sheshes, one of the holy Amora'im, say such a seemingly derogatory remark about Rav?
(a) The CHAVOS YA'IR (#152) explains that Rav Sheshes' statement was not one of derision, G-d forbid, but rather one of great adulation and praise to Rav. He was saying that Rav was so great that he never could have much such an error unless he stated his ruling while he was falling asleep. (See also YOSEF DA'AS to Yevamos 24b.)
(b) The IMREI BINAH (Hakdamah, end of footnotes) quotes the RAMA MI'PANO (end of YONAS ILEM) who asserts that Rav was Rav Aba, who was the closest and most esteemed disciple of Rebbi Shimon bar Yochai, the Tana who mastered the hidden, innermost parts of the Torah. Rav Sheshes knew that all of the words of Rav were based on the hidden parts, the inner essence, of the Torah, even those statements that seemed to be based on the revealed parts of Torah.
The ARIZAL writes that the concept of sleep was created by Hash-m so that a man's Neshamah would leave him and be able to fathom the profound secrets of the upper worlds, which would be impossible for a person to comprehend while his Neshamah was confined to his body.
Rav Sheshes understood this, and he said that since he cannot understand the words of Rav, undoubtedly Rav must have said these words while he was sleeping, when his Neshamah was able to fathom the profound secrets of the inner-essence of the Torah which cannot be understood by man while he is awake and while his Neshamah is confined within his body. (See also Insights to Zevachim 25:2, Bava Metzia 20:5, Bava Kama 65:2.)