Shabbos 90b - Handing a Child non-kosher Food

The gemara concludes that if there would be a legitimate concern that a child will eat something not kosher that is handed to them, one may not hand it to them. The machlokes between the tana kama and r. yehuda whether one can hand a child a non-kosher live bug, boils down to an assumption as to what the child will do with it when it dies. The t.k. is concerned the child will eat it and therefore says you can't hand even a live non-kosher chagav to a child because it may die and he will eat it, but r. yehuda says that since it was his pet, he will mourn its death, not associate it with food and therefore he won't eat it.

Rashi points out that we pasken that when a child is eating something not kosher, it is not incumbent upon others to stop him (aside from a child who reaches chinuch in which case his father is obligated to stop him). Why then is it forbidden to give him a non-kosher chagav to play with? Rashi explains that since there is an issur d'oraysa to feed a child something not kosher, handing something not kosher to a child when he is likely to eat it is tantamount to feeding him issur. Rashi implies that placing not kosher food down in front of a child is an issur d'oraysa of לא תאכילום - להזהיר גדולים על הקטנים. However, the Ritva writes that one may not give the non-kosher item to a child because it is "like" feeding him. The language of the Ritva implies that it is not actually an issur d'oraysa, but since it is very close to actually feeding him, it is assur m'drabonon.

The gemara also says that if there is a concern that he will eat a live chagav, one may not even give a child a kosher chagav because eating it while it is alive is still an issur of בל תשקצו, which is a general issur against doing things that are disgusting. The source of this idea is a gemara in Makos 16b that if one drinks out of a horn that is used for blood letting they are in violation of בל תשקצו. We generally assume that this pasuk is merely an אסמכת for disgusting activities but would not be an issur d'oraysa. 

Based on this assumption, the Mishneh L'melech (ma'achalos asuros perek 27) asks on the Rashba who says that the issur to feed a child an issur d'rabonon only applies to prohibitions of the Torah, not to Rabbinic prohibitions, provided that it is a need of the child (which is against the p'sak of the shulchan aruch o.c. 343 where the shulchan aruch explicitly writes that you can't even feed a child an issur d'rabonon. See Biur Halacha who cites R. Akiva Eiger who relies on the Rashba). According to the Rashba, why would the gemara assume that you can't give a child a chagav that is kosher, since even if he eats it, it is only an issur d'rabonon? 

The Beis HaLevi (3:55:1) answers that even the Rashba only permits it when it is for the well being or benefit of the child, and we don't consider eating a chagav to qualify. It is not clear to me why a chagav which is apparently edible, would not be considered for the benefit of the child. R. Chaim Ozer (Achiezer 3:81:5) answers that the Rashba only permits other activities which aren't sourced in the Torah, just derived from the 3 places where the Torah warns adults not to feed issur to children (tu'mah, dam, and sheratzim). But by the 3 places where the Torah explicit writes לא תאכלום and we darshen לא תאכילום, even the Rashba admits that since it is עיקרו מן התורה we don't allow the feeding of an issur d'rabonon to a child. Since eating a live chagav is an issur d'rabonon based on בל תשקצו which is the la'av of eating sheratzim, we forbid even issurei d'rabonon.

Shabbos 84b - Tumas Heset

The gemara in trying to figure out the source for there not being tumas midras by earthenware vessels quotes Rava citing a pasuk that implies that an earthenware vessel that is sealed would always remain tahor. The implication is that even if a Nida would sit on it, it would remain tahor. The seal only prevents tumas ohel, but wouldn't prevent tumah from a nida sitting on it. From this we conclude that there is no tumas midras by earthenware.

Rashi understands that the implication of the pasuk is that there would be no way at all for this sealed earthenware vessel to become tamei through a Nidah. Why wouldn't it become tamei by the nidah moving it, - טומאת היסט? Rashi explains that only something that is susceptible to tumah through touch can be tamei by moving it, therefore a sealed vessel which one cannot touch on the inside, wouldn't become tamei from moving it. Tosafos disagrees with Rashi and says that the צמיד פתיל - seal, doesn't prevent טומאת היסט and if a Nida would move it, it would become tamei.

The gemara on 21b says that they found a jar of oil that was sealed by the seal of the kohein gadol indicating that it was still tahor. Tosafos asks how can they be sure it was tahor? Although a goy would not have touched it, there is a chance that a goy moved it rendering it tamei through טומאת היסט. Even though on a Torah level goyim aren't tamei, chazal were gozer to treat them like zavin for all purposes (83a). Why are we not concerned that a goy moved it? This question is really Tosafos lishitasam that צמיד פתיל doesn't prevent tumas heset, but according to rashi there is no concern for tumas heset since it is sealed.

Tosafos answers that it was situated in the ground in a way that it is clear that it hadn't been moved at all. The Ran says that since they were looking for precious items, had they found it, they would have opened it. The fact that it was still sealed indicates that they never found it, therefore there is no concern that they moved it.

Shabbos 79b - Writing Mezuza in Order

We usually assume l'halacha that both a mezuza and tefillin must be written in order, which means that if a p'sul is found in an earlier letter, the only way to fix it is to scratch out every letter until the end of the entire mezuza and then rewrite it. That is why we generally are unable to fix tefillin and mezuzos when they have a p'sul, to the exclusion of a sefer torah on which there is no din of כסדרן and is not required to be written in order.

The gemara talks about converting a sefer torah into a mezuza or tefillin. The only issue that the gemara has with this is that a sefer torah has more kedusha than tefillin and mezuza, and one cannot downgrade kedusha. From this the gemara derives that there must be some material on which a sefer Torah can be written, that would be acceptable for tefillin and mezuza (Tosafos holds that for sefer torah we not only permit the 3 forms of parchment - גויל, דוכסוסטוס , קלף, but we even permit the use of paper. Tosafos points out that the yerushalmi rejects the use of paper).

Tosafos questions how one would convert a sefer torah into a mezuza since a mezuza requires the parsha of והיה אם שמוע to be written immediately after שמע, yet in a  sefer torah they are far apart. One of the possibilities that Tosafos suggests is that if והיה אם שמוע happens to be written on the top of a column, one can cut it out from a sefer torah and write the parsha of shema on the margin above. The problem with this that Tosafos does NOT address is that this would seem to be a violation of כסדרן since the parsha of והיה אם שמוע will be written prior to the writing of שמע?

The Taz (Y.D. 190) writes that we see from this Tosafos that the requirement of כסדרן by mezuza does not demand that the parshiyos be written in order, just that within each parsha each word and letter is written in order. The Shach in Nekudas HaKesef disagrees and is madchik in Tosafos to explain that even Tosafos requires כסדרן on the parshiyos.

The Chasam Sofer (teshuvos y.d. 282) asks that for tefillin we learn from והיו that they need to be written in order. Although there is room to reject the mechilta that applies the din of כסדרן to mezuza, and hold that there is no din of k'sidran by mezuza. The compromise requiring the letters and words to be k'sidran but not the parshiyos doesn't make sense because by tefillin we require even the parshiyos to be written in order?

The Chasam Sofer has a fascinating approach. He holds that the din of כסדרן is not focused on the order. Rather it is a din that when the parsha of והיה אם שמוע is written, it must be written with the kedusha of mezuza. The way this is accomplished is by having the parsha of שמע proceed it, it is considered to be written with kedusha of mezuza. Therefore, if והיה אם שמוע is written before שמע in general, it would be passul because the parsha of והיה אם שמוע is written without kedushas mezuza. However, when והיה אם שמוע is written within the sefer torah itself, it is written with kedushas sefer torah which is a greater kedusha than mezuza. Therefore, specifically in the case where והיה אם שמוע is written within the context of a sefer torah and assumes kedusha through the sefer torah, can we allow shema to be written afterwards on the upper margin.

Shabbos 73b - Intent Being Integral To The Melacha

The gemara says that if one prunes and needs the wood, he is in violation of both planting and harvesting. Tosafos explains that the implication of the gemara is that if one doesn't need the wood, he is only in violation of planting, not harvesting. This would seemingly only be true according to Rav Shimon who holds that one is not chayev for a melacha sh'ein tzricha l'gufah, therefore although one is technically violating both planting and harvesting, since he doesn't need the wood, he isn't chayev for harvesting. But, Tosafos says that the gemara implies that the requirement of צריך לעצים, needing the wood, is necessary even according to R. Yehuda. The rationale is that the act of pruning is not considered harvesting at all unless his intent compliments the act, meaning that he is doing it for the wood.

Tosafos enlightens us to a fascinating concept. Sometimes the melacha is defined simply by the action that one is doing. For example, if one digs a hole they are doing a melacha of plowing, even if they don't need the hole. Whether they are chayev or not will depend on the machlokes between R. Yehuda and R. Shimon, but either way we consider them to have violated the melacha. However, some melachos are DEFINED by the intent one has when doing them. If one were to cut branches without the intent to use the wood, the act is just defined as an act of pruning which is a melacha of planting, not harvesting. Tosafos proves this point from קורע על מנת לתפור and from מוחק על מנת לכתוב. Tosafos holds that for tearing and erasing the requirement for it to be for the purpose of sewing and writing respectively, is not merely a condition in being a מלאכה הצריכה לגופה or avoiding the problem of it otherwise being a destructive act. Rather, Tosafos holds that the melacha is defined as tearing for the purpose of sewing and erasing for the purpose of writing. R. Akiva Eiger (gilyon hashas) points this out. Even if the act of tearing or erasing would be done for a constructive purpose, just not for the specific purposes of sewing and writing, it would not be a violation of the melacha. This would helps explain the Rosh (siman 6) who writes that untying is only a violation if done for the purpose of tying. The Tiferes Shmuel asks that since untying something isn't a destructive act, why do we insist on untying being solely for the purpose of tying. Even if not for the purpose of tying he should be chayev since it is a constructive act? Based on Tosafos we can suggest that the requirement of it being for the purpose of tying is not to make the act productive, rather it is the very definition of the melacha similar to tearing and erasing.

The difficulty with Tosafos is that they define the act of tearing to be "tearing for the purpose of sewing", implying that for any other constructive purpose, one would not be chayev. R. Akiva Eiger points out that this contradicts the gemara 105b that says if one tears his clothing as kriah for a relative or tears something to alleviate his anger, since it is constructive they are chayev for tearing. The gemara strongly implies that tearing need not be for the purpose of sewing so long as it is for a constructive purpose, contradicting the assumption of Tosafos?

R. Elazar Meir Horowitz, without citing R. Akiva Eiger, addresses his question. Tosafos doesn't mean to say that the only time one is chayev for tearing is when it is done for the purpose of sewing. So long as it is done for some other constructive purpose, they are chayev. However, when there is no other constructive purpose other than to resew, we insist that he is actually doing it for the purpose of resewing, not merely that it be fit to resew. We see that even though to avoid the mekalkel issue it should be sufficient that it is torn in a way where it can be resewn, he is only chayev when he is doing it for the purpose of resewing, because that becomes the definition of the melacha.

Shabbos 72b - Bowing In a Church

The gemara tries to figure out the case where one inadvertently violates avoda zara and is obligated to bring  a korban for the violation. The gemara says if he is in a church but thinks that its a shul (maybe he thinks the guy in front on the cross is Moshe Rabbeinu) - הרי לבו לשמים, his heart is to heaven. Meaning, that is not a violation of avoda zara at all and he doesn't need to bring a korban. The Ritva points out that even if it wouldn't be לבו לשמים, so long as it wasn't לבו לעבודה זרה, he wouldn't be obligated to bring a korban. The only reason the gemara goes to the extreme of לבו לשמים is because when a person is in shul, it is likely that his heart is to Hashem.

Rashi also seems to be bothered by why we need to say that in his mind he is both inside a shul and לבו לשמים. The Ritva seemed to understand that the thinking it being a shul is essential, but the לבו לשמים is not necessary, so long as his heart isn't to avoda zara. Rashi on the other hand seems to say that the כסבור בית הכנסת הוא, the thinking of a shul is not necessary. Rashi comments - ומה חיוב יש כאן, אפילו ידע שהוא בית עבודה זרה והשתחוה בו לשמים אין חיוב כאן. Rashi holds that since his heart is to Hashem, who cares where he is standing. Even if he is in front of an avoda zara and well aware of where he is, so long as his heart is to Hashem, he is not obligated to bring any korban. From Rashi we learn that so long as someones heart is to Hashem, even if it looks like they are worshiping avoda zara, they are not chayev misah or a korban (perhaps what compels rashi is that otherwise, we have a perfect case where he is chayev a korban, he is in a church and bowing with his heart to Hashem thinking that it is permitted to do so). The Ritva comments that although the issur avoda zara may be dependent on what he has in mind, the din of יהרג ואל יעבור is certainly not dependent on what he has in mind. If by simply having לבו לשמים the halacha would be that one wouldn't have to sacrifice his life, there would never be a din of יהרג ואל יעבור because we would always tell the person that his heart should be to Hashem. Therefore, the Ritva concludes that the din יהרג ואל יעבור must not be dependent on the issur avoda zara, rather on chilul hashem. Since there is a chilul hashem we demand that he give up his life and not bow down.

Rav Moshe (Dibros #27, pg. 536) struggles with Rashi. Rav Moshe assumes that when a person knows that he is in a church and bows down in the church, even if his heart is to Hashem he is serving avoda zara and chayev. The fact that his heart is to heaven becomes irrelevant since to everyone watching it looks like he is worshiping avoda zara. Rav Moshe suggests that Rashi must be describing a situation where the people watching are confident that he believes in Hashem and his heart is to shamayim. Nevertheless, Rav Moshe says that it would at least be a d'oraysa violation of chilul hashem which would ruin his presumption of innocence thereby rendering his thoughts to merely דברים שבלב and therefore he should be chayev a חטאת in this situation. Perhaps it is talking about when he is alone and therefore believed to say that his heart was to Hashem.

Shabbos 71b - Shiur of Achilas Pras

It is well accepted that the shiur to combine eating into one act is כדי אכילת פרס. However, there is a contradiction between two statements of Rashi (d.h. cheilev, and She'im) how this is measured. The first Rashi implies that it is calculated by their being a כדי אכילת פרס in between the two eatings. Meaning, that the time that one is actually eating doesn't count, therefore as long as the time in between is less than a pras the two acts of eating combine together. However, the second Rashi implies that one must consume a kezayis within the amount of time it takes to eat a pras, implying that it is measured from the start of the first eating until the conclusion of the eating. Which one is it?

The Rashash cites a Sefer Be'er Avrohom (author of maskil l'eisan) - HERE, who asks this question on Rashi. He points out that both the Mishna in Krisus (3rd perek) and Rashi in Pesachim 44 imply that for something to be considered one act of eating, the entire kezayis must be consumed within an amount of time of כדי אכילת פרס. Whereas Rashi in Menachos 75b implies that so long as the amount of time in between is less than כדי אכילת פרס, the the two act of eating combine to a kezayis. The sefer Be'er Avrohom makes a distinction between an aveira and a mitzvah. He suggests that to be in violation of eating something forbidden, one must consume the entire kezayis in a כדי אכילת פרס. But, when one is eating a kezayis of matzah, so long as there is no pause in between his achila that is longer than כדי אכילת פרס, it all combines to enable him to be yotzei his mitzvah, even though it took longer than כדי אכילת פרס to eat the kezayis. With this he explains the Braisa in Pesachim 114b that if one eats a half of kezayis of maror and then another half, they combine so long as there isn't a delay in between that is longer than כדי אכילת פרס. This doesn't easily answer the contradiction in Rashi in our sugya, but the Be'er Avrohom suggests that the first Rashi is trying to say a chiddush that even if the delay in between the two eatings of cheilev is longer than כדי אכילת פרס, they combine together to be considered one eating.

The Rashash rejects the distinction of the Be'er Avrohom to say that mitzvos are different than aveiros. His proof is from a Yerushalmi in Shavuos (perek 3) cited by Rif and Rosh (end of Pesachim) that if one makes a shavua not to eat matzah on the night of pesach, it is a shavuas shav, so he gets malkus and eats matzah. The Yerushalmi assumes it is impossible to fulfill the mitzvah of eating matzah without violating the aveira. Why is this impossible? One can eat a kezayis with a break of just under a כדי אכילת פרס in between each half kezayis, thereby fulfilling the mitzvah of matzah but not violating the shavua since there will be more than a כדי אכילת פרס from the beginning to the end of his kezayis.

It is also difficult to understand what rationale there can possibly be to differentiate between a mitzvah and an aveirah. For some reason the assumption is that for a mitzvah, so long as one is eating the entire time, we don't care how long it takes him to eat the kezayis, whereas for an aveira it only qualifies as a violation of eating a kezayis when one eats a kezayis within כדי אכילת פרס.

Shabbos 69b - Count 6 Days and Keep Shabbos

The gemara says that when one loses track of when shabbos is, they should count six days and keep the seventh as Shabbos. The gemara makes it clear that the purpose is not because we assume that the 7th day will actually be shabbos, but rather we don't want him to forget the concept of shabbos (rashi) therefore the Rabbonon impose this system to remember the concept of Shabbos. The gemara also says that it is forbidden to do melacha any of the days of the week, beyond what is needed to survive for that day, because every day is a safeik shabbos and is permitted only for pikuach nefesh. The M.B. says that we aren't entitled to go after the "rov", the majority of days which aren't shabbos because one of the seven is definitely shabbos and therefore it qualifies as kavuah where we don't follow the majority.

The gemara has trouble figuring out what makes the 7th day stand out over the rest since on all days he can do what is needed to survive but not more. The only thing that the gemara comes up with is that on the 7th day he will make kiddush as it comes in and havdala as it goes out - that is the only difference between his 7th day and all other days. Tosafos asks why doesn't the gemara say that he can travel beyond his techum all other days but not on the 7th day? Tosafos offers two answers: 1. It is not a significant difference between the 7th day and the 6 earlier days by passively sitting and not travelling. 2. He can travel even on the 7th day since that is necessary to get him out of his present situation. Regarding the second answer of Tosafos, there seems to be a machlokes Ran and Ritva as to whether we allow him to travel beyond his techum, even according to R. Akiva where techum is d'oraysa, or are we only permissive because it is considered d'rabonon.

According to the second answer of Tosafos that a passive recognition is sufficient, the Biur Halacha questions why we don't say that Shabbos stands out in that he wears tefillin everyday except his 7th day. From this the Biur Halacha concludes that Tosafos must hold that he actually would need to put on tefillin everyday including his 7th day.

It comes out that on a Torah level, we regard every day as shabbos and don't allow any work beyond pikuach nefesh, but on the other hand regard every day as not being shabbos and require him to put on tefillin.

Shabbos 66b - Walking with a Cane

The Mishna permits (according to R. Meir) a person who has an amputated leg to go out with his "kav" - prosthetic leg. Tosafos has different approaches as to what function the kav actually served. Tosafos assumes that if this is the his primary method of moving around, we can prove from here that an amputee can also use a crutch or crutches which is his primary method of movement. However, if the prosthetic leg that the mishna is speaking about is more for appearance and aesthetics, we can't draw a proof from here regarding the use of a cane or crutches.

The Shulchan Aruch 301:17 paskens that a person who can walk without crutches may go out with crutches on shabbos. The assumption is that since he can't move without them, they are considered a "shoe" for him and permitted to be used on Shabbos. But the Shulchan Aruch continues that if he can move without them and is only using them to strengthen himself or hold himself better, it is forbidden. It isn't clear from the Shulchan Aruch whether the problem is that since he can move without it, we are afraid he may come to carry it, or since he can move without it, it's not considered a shoe hence a Torah violation of carrying. The Biur Halacha cites the Levush who says that on a Torah level it is not considered carrying since he is leaning on it, but on a Rabbinic level we are concerned that since he doesn't need it that desperately, he will come to carry it. However, the Biur Halacha rejects this approach based on the gemara 66b. The gemara says that a cane used by the elderly is to enable him to walk straight and straighten himself up since his legs shake, but it isn't made for the leaning of one's entire body and therefore it is not tamei as a midras. From here we see that something which is used to strengthen oneself and not to fully lean on, such as a cane (vs. a crutch), is not tamei midras and therefore on shabbos should be considered carrying. Therefore, the M.B. (64) paskens that an elderly person who can walk around inside his home without a cane, but when he goes out he uses a cane for the security and sturdiness, it is forbidden and is considered a משוי. The M.B. holds that it's not only a concern that he may come to carry it, but is actually an issur d'oraysa of carrying. However, if he is so old that he can't even move around inside without it, it becomes like the kav of a amputee that can be used in the reshus ha'rabim.

Based on this, those people who use walkers to enable themselves to walk, the halacha would be that if they require those walkers inside, they can use it outside as well. But if they only use it when going out to secure themselves and prevent themselves from falling, it is assur to go out with it on shabbos when there is no eiruv.

Shabbos 64b - Not to be Degraded in the Eyes of Her Husband

The gemara says that chazal wanted to forbid a woman from wearing any kind of tachshit on shabbos out of fear that she may come to carry it, but permitted two specific types of head coverings שלא תתגנה על בעלה. The gemara continues that we find a similar concept. Chazal wanted to darshen from the pasuk of והדוה בנדתה which implies she must maintain herself in a state of nidda, that when a woman is a nidda she is forbidden to put on make up, jewlery or other types of adornments. However, Rabbi Akiva rejected this drasha כדי שלא תתגנה על בעלה which may lead to him divorcing her, and therefore darshened the pasuk to simply say that she remains a nidda until going to the mikvah. 

Firstly, it seems strange how R. Akiva could reject the drasha based on the concern that it will be bad for shalom bayis and lead to divorce. It seems as if the zekainim harishonim were not merely instituting an issur d'rabonon but rather darshening a pasuk. How can R. Akiva reject this drasha on the basis of it detracting from shalom bayis? We see from here that R. Akiva could not accept their interpretation of the pasuk to be an accurate drasha because he felt that there is no way the Torah would forbid something that will lead to her being מתגנה על בעלה which can ultimately end in divorce. Based on his sevara he insists that the Torah mean something else entirely.

In explaining the heter for a woman to wear these head pieces on shabbos to prevent her from being מתגנה על בעלה, Rashi writes התירו לה קצת קישוטים הנאים. At first it would seem that in the context of nidda also the sevara should only permit her to war קצת קישוטים הנאים, some nice adornments, only enough that she not be מתגנה על בעלה. However, from the fact that Rashi only writes this in the context of shabbos prior to citing the Braisa by nidah, it implies that when R. Akiva rejects the drasha by niddah כדי שלא תתגנה על בעלה, he rejects it entirely. Therefore, a woman who is a nidah would be allowed to dress however nice and fancy she chooses, and is not required to hold back any form of קישוט. The rationale for the distinction is simple. By shabbos where the Rabbonon are concerned about carrying, they would only permit the bare minimum necessary to prevent her from being מתגנה על בעלה. But for a Nidah, once R. Akvia rejects the drasha there is no basis for any limitation. This seems to be the approach of the Rambam who writes (End of perek 11 in Issurei Biah) - מותר לאשה להתקשט בימי נדתה כדי שלא תתגנה על בעלה. The Rambam sounds like we permit everything without any hesitation.

However, the Shulchan Aruch (Y.D. 195:9) in recording this halacha writes:

בקושי התירו לה להתקשט בימי נדתה אלא עדי שלא תתגנה על בעלה. The language of בקושי and the language of אלא imply that there actually is an issur. It sounds like the Shulchan Aruch is understanding that we would only permit what is necessary. It is true that one can read the Shulchan Aruch to simply be saying that they would not have permitted it if not for שלא תתגנה על בעלה, but now that they permitted it, everything is mutar as the Rambam writes. But, if that is the intent of the Shulchan Aruch, all he is really saying is a historical fact of what would have been. Why would this be paskened as a halacha in Shulchan Aruch? Perhaps this question compels the Gr"a (13) to cite a braisa in Avos D'rabi Nosson:

כל המנבלת עצמה בימי נדתה רוח חכמים נוחה הימנו, וכל המתקשטת עצמה בימי נדתה אין רוח חכמים נוחה הימנו. The braisa says that it is proper for a woman to make herself look unattractive during her niddah time. The Gr"a comments that this braisa is not in accordance with the z'kainim harishonim who R. Akiva disagreed with because according to them it would be a real issur, not just אין רוח חכמים נוחה הימנו. Therefore, it must be even according to R. Akivah. Based on the Gr"a, although chazal did not forbid ANY forms of tachshit for a nidah and she is allowed to dress herself up as nicely as she wants, on a personal level she should strive to not make herself look attractive during her time of being a niddah. This is the message that the Shulchan Aruch is trying to say. R. Akiva rejected the notion that chazal would impose an issur, but he didn't reject the perspective that while a woman is a niddah she should not be מתקשטת. Based on this, although chazal couldn't forbid a niddah from being מתקשטת, it is still recommended on a personal level to abstain from doing so.
This is against some of the commentaries on avos d'rabi nosson who assume that the braisa cited at the beginning of perek 2 doesn't follow the opinion of R. Akiva. Based on this, we would follow R. Akiva so that it isn't even commendable to abstain from קשוט during her niddah time. On the other hand, the exact opposite is also a possibility. The Toras Hashlamim (also cited in sidrei tahara) suggests that only R. Akiva is very worried about her being מתגנה על בעלה because he holds (9th perek of gittin) that grounds for divorce could be as simple as finding another woman he likes better. Since R. Akiva is so permissive about divorce, he has to take special measures to prevent it. Therefore, we who don't pasken like R. Akiva in being so lax about divorce, would not be so sensitive to her being מתגנה על בעלה and would hold that it is forbidden for her to be מתקשט while she is a niddah.

Shabbos 64b - Ma'aris Ayin

Rav says that anytime chazal forbid something on the basis of ma'aris ha'ayin, it is forbidden to do even in private when no one else is watching. The gemara cites two Braisas whether an animal can be in a chatzer (not reshus harabim) while wearing a bell on shabbos which looks like it is being taken to the marketplace to be sold. The gemara says that the two braisas are dependent on a machlokes tana'im whether we forbid ma'aris ha'ayin even in private, as Rav holds, or only in the public eye. There is a machlokes whether one can hang out clothing to dry which gives the appearance of it being laundered on Shabbos. The opinion who says it is permitted to hand it out in an area where people cannot see it is against Rav, and the other opinion conforms with Rav.

Tosafos says that some prove that we don't pasken like Rav based on a gemara in Chulin which forbids Shechita in a hole because it looks like it is being done for avoda zara, but permits it in a chatzer. This seems to imply that so long as it is being done privately it is permitted. Tosafos rejects the proof and says that the advantage of the chatzer is not that it has less exposure to the public eye, rather, in a chatzer people assume you are shechting in a hole to avoid dirtying the chatzer. In other words, when the advantage of the private area is merely less exposure, chazal still maintain the issur. But if the advantage of the private area is that the circumstance avoids the entire issue of ma'aris ayin, it is permitted. Based on this, it seems to me that one may hang coats and jackets that are wet from the rain in their bathroom, without any concern. Although the fact that it is being hung indoors doesn't avoid the ma'aris ayin concern, the way in which it is being hung and the place in which it is being hung doesn't mislead people into thinking that it was actually laundered on Shabbos. The Sha'ar Hatziyun 301:212 says something similar, that if the garments aren't spread out as they are typically done after laundering, there is no issur.

There is a Tosafos in Kesubos 60a who says that although we pasken like Rav and forbid ma'aris ayin even in private, that is only when the being watching would suspect you of an issur d'oraysa, but if they would just suspect you of an issur d'rabonon, it is permitted in private. The Magen Avrohom asks from the gemara in our sugya that says that according to Rav (and the tana'im that forbid spreading out clothes even in private) it is forbidden for an animal to go into the chatzer with a bell because people will think that it is being taken to the marketplace. Selling an animal on Shabbos is only an issur d'rabonon, yet the sugya assumes that it would be forbidden even in private. This seems to be clearly against Tosafos? The Maharsham says that based on Tosafos 150a that the business shevusim that are learned from the pesukim in Yeshaya are like d'oraysa, it could be that selling an animal in the marketplace can be considered an issur d'oraysa.

The Biur Halacha 301:45 writes that since there are some poskim who reject Rav and hold that ma'aris ayin is permitted in private, one can at least rely on Tosafos who says that it only extends to private areas when the person would suspect you of violating a d'oraysa, not if they would only suspect a Rabbinic violation. Although he points out that our sugya doesn't seem to support the distinction of Tosafos, he doesn't offer any explanation to reconcile Tosafos in kesubos with our sugya.
See also the last pischei teshuva in hilchos chala (yoreh deiah) where he discusses whether Tosafos in kesubos can be relied on l'halacha.

Shabbos 63b - Are Goyim Considered an Ervah?

The Ya'avetz brings a proof from our gemara that Goyim are considered an Erva in the context of יהרג ואל יעבור. The gemara says that the aveira the Jews committed in the war against Midyan was that they were זנו עיניהם מן הערוה, which implies that even goyim have a status of Ervah.

The Rama (Y.D. 157:1) writes that a gentile man who has relations with a Jewish woman is not considered giluy arayos. The Shach (12) writes that all the Rishonim agree that a Jewish man with a Non-Jewish woman is considered giluy arayos. The justification to consider it to be giluy arayos and יהרג ואל יעבור even for a non-married gentile woman, is because if a Jew would have relations with her in a public way there is a d'oraysa halacha of קנאין פוגעין בו, therefore she is considered and ervah. The Shach understands that most Rishonim assume that the requirement of יהרג ואל יעבור would only apply if he is being forced to have relations with her in a public manner (meaning people will know about it, like by Ester), but if he is only being forced to have relations privately, he doesn't need to give up his life. However, he then cites the Nemukei Yosef who says that since he is chayev kareis even if kana'aim don't attach him, we consider her to be an ervah and even בצנעא there would be a requirement of יהרג ואל יעבור. The Nodeh B'yehuda (cited by Pischei Teshuva) explains that the opinion of the Nimukei Yosef can be justified because he may hold that even on an issur d'rbaonon of arayos we say יהרג ואל יעבור, therefore even בנצעא which is only d'rabonon we can say יהרג ואל יעבור. But the Shach himself (10) who only says יהרג ואל יעבור  by a d'oraysa, should not be able to hold that here is יהרג ואל יעבור for a צנעא violation.

It is possible that when our gemara uses the term ervah, it doesn't mean it in the literal sense and wouldn't prove that goyim have the status of ervah for יהרג ואל יעבור. However, according to the Ya'avetz who proves from our gemara that goyim are called an ervah for יהרג ואל יעבור, it must be that he assumes like the Nimukei Yosef that even בצנעא the din would be יהרג ואל יעבור. According to the other Rishonim, we don't consider goyim to be an ervah, just that in the circumstance where their is a din of קנאים פוגעין בו because its done publicly, since the Torah considers him worthy of death, we say that he is also obligated in יהרג ואל יעבור. According to this approach it wouldn't make any sense to consider goyim an ervah in the context of hirhurim.

Shabbos 63a - Difference Between This World and Days of Moshiach

The gemara has two opinions whether the time period that the nevi'im said prophesy about was referring to the days of Moshiach, indicating that there will be complete peace and significant differences between this world and the days of Moshiach, or whether they are saying their prophesy about olam ha'ba which comes after the days of Moshiach. Shmuel assumes the latter approach and therefore says that there will be no difference between the world we live in now and the days of Moshiach except for not being in servitude to the goyim. According to Shmuel, even in the days of Moshiach there will be both poor people and rich people and there will also be a need for weapons 

Rav Yaakov Emden asks that the need for weapons should be dependent on being subject to the goyim. Since in the days of Moshiach we won't be under the control of the goyim, why would we require weapons? He answers that since it will be a time period where the victory of Yaakov over Eisav is very fresh, we will still require weapons to represent the victory and remind Eisav that we entered the realm of ורב יעבוד צעיר. The Ya'avetz understands that the days of Olam Ha'ba will be an entirely different reality where we won't even need to represent ourselves as being in control, but in the days of Moshiach we will still need to use the "props" to remind Eisav that we are in control.

Tosafos comments on the statement of Shmuel that there will also be another significant difference between nowadays and the days of Moshiach aside from the שעבוד גליות. In the days of Moshiach we will have Yerushalayim restored and a Beis HaMikdash. Why does Shmuel not mention this? Tosafos answers that the אין בין is not literal because there will be other differences. Rav Yaakov Emden (ya'avetz) adds that the focus of Shmuel is just on the nature of the world. The world will run in the days of Moshiach its natural course as it does nowadays. This seems to be Tosafos intent as well that אין בין is literal, but it doesn't refer to everything, it just refers to the world running naturally.

Rav Moshe (Heara 26) makes a very strong point. He doesn't understand why Tosafos is even bothered by the question of why Shmuel doesn't mention Yerushalayim and the Beis HaMikdash. The rebuilding of Yerushalayim and the Beis HaMikdash is not a mitzva that is going to be reintroduced in the days of Moshiach. It is a mitzvah today as much as it will be then, just that we are prevented from doing so due to the שעבוד גליות. We may also be missing education in terms of how to build it since we are missing nevuah. But these things are all part of the definition of ימות המשיח when the goyim will no longer have control over us. We will be free to rebuild Yerushalayim and the Beis HaMikdash. The Rambam (Melachim 11:1) actually lists under the responsibilities of Moshiach to restore the malchus beis dovid, rebuild the Beis Hamikdash and gather the Jews from wherever they are dispersed. The Rambam includes all this under the heading of שעבוד גליות, therefore the אין בין is completely literal and accurate.

Shabbos 62a - Tefillin for Women

Rav Yosef suggests that men and women are treated as separate categories, therefore something which qualifies as a tachshit for a man and permitted to be worn on shabbos will not be a tachshit for a woman, unless it is also normal for her to wear that type of item. The gemara asks from a Braisa which permits a woman to wear tefillin in from the reshus harabim on shabbos. The assumption is that tefillin is a time bound mitzvah from which women are exempt. Therefore, if we assume that "women are a nation unto themselves" and what qualifies as a tachshit for a man doesn't impact a woman, it should be forbidden for a woman to wear tefillin on shabbos because it should be considered carrying? The gemara responds by saying that the author of the braisa holds that one is obligated to wear tefillin both at night and on Shabbos making tefillin a mitzvah that is not time bound. Since women are obligated as much as men, it is considered a tachshit for women also.

There is a very serious question that can be asked on this gemara. There is a machlokes between Rabbeinu Tam and the Rambam whether or not women can make a bracha on time-bound mitzvos, but all agree that she receives reward for fulfilling these mitzvos as an אינה מצווה ועושה. Being that a woman receives reward for wearing tefillin, how can we consider her wearing tefillin to be an act of carrying? However, if we ask the question as simply as we just did, the answer is obvious. Although women get a mitzvah for wearing tefillin, we are speaking about shabbos for which there is no mitzvah to wear tefillin. Therefore, for a man who wears tefillin during the week it is considered a tachshit even on Shabbos when there is no mitzvah (as the ritva explains on the gemara 61a) but for a woman who isn't wearing tefillin during the week, since on Shabbos there is no mitzvah to wear tefillin, it is not considered a tachshit for her. If we take this approach, it should follow that if shabbos would be a time for tefillin and women would be doing a mitzvah by wearing tefillin on shabbos, it should be permitted for them to wear tefillin, even if they aren't wearing tefillin during the week. If this were true, the gemara should have simply answered that the Braisa holds that Shabbos is z'man tefillin, so that even if night is not a time for wearing tefillin making tefillin a time-bound mitzvah, they can still wear tefillin on Shabbos since by wearing it they are fulfilling a mitzvah. Why does the gemara feel compelled to say that both night time and shabbos are a zman tefillin and transform the entire mitzvah into a non time-bound mitzvah, as Rashi explains. It should have been able to justify the women wearing tefillin without having to go to such an extreme?

From the fact that the gemara goes to the extreme that it does, it implies that the only justification to permit women to wear tefillin in reshus harabim on shabbos is if they are exactly equal to men in the obligation of tefillin, but by simply being able to perform a mitzvah by wearing tefillin on shabbos wouldn't justify the right of a woman to wear tefillin. Why?

I found that Rav Moshe (Dibros Moshe, Siman 50, anaf 4, pg. 336) addresses this issue. At first he suggests that based on Rashi in Eruvin 96 who considers women performing time-bound mitzvos to be bal tosif, and even Tosafos who at least when it comes to the mitzvah of tefillin considers it inappropriate for woman to wear since it is hard to maintain the proper level of cleanliness, we can explain our gemara. Since women are not supposed to perform this mitzvah, it isn't considered a kiyum mitzvah for them to wear tefillin on shabbos even if shabbos is a z'man tefillin. Therefore, the gemara is forced to say that women are fully obligated in this mitzvah. However, Rav Moshe suggests that if the gemara was asking from the perspective of issur rather than p'tur, it should have said so explicitly and also should have cited some proof that there is indeed an issur. Therefore he suggests that even if women would be fulfilling a mitzvah by wearing tefillin on shabbos, this would not justify their ability to wear tefillin in the public domain. The rules of what is considered a tachshit or malbush is very practical. If women have the practice to generally wear tefillin, it would be regarded as a tachshit, but if they don't have that practice, even if they would be performing a mitzvah by doing so, it is not considered a tachshit. Therefore, the only justification to allow a woman to wear tefillin on shabbos is to change the nature of the mitzvah to be a non time-bound mitzvah making women completely equal to men in this mitzvah.

Shabbos 58a - Crowns for Kallos

The braisa on 57b says that this headband called איסטמא which is used to help contain hairs that can't be contained by the standard head covering, is not a problem of shatnez. R. Shimon adds that it can be worn by a kalla and doesn't violate the gezeira that after the destruction of the beis hamikdash brides cannot wear crown-like head pieces. Regarding the shatnez issue, there is a machlokes between Rashi and Tosafos. Rashi says that it is made from a felt material that has never been spun into strings and woven. It is just flattened fibers that are held together and therefore not a violation of shatnez. Tosafos disagrees because even on felt there is a Rabbinic prohibition. Therefore, Tosafos says that since it is a coarse material, in conjunction with it being felt and not proper threads, there isn't even a Rabbinic prohibition. According to both these approaches it is very understandable why it wouldn't be a violation of עטרות כלות since it is made of material in a very inferior manner and certainly doesn't contain any type of precious metals or stones. The Shulchan Aruch 561:4 even permits crowns made of regular material so long as there are no precious metals in it.

However, Tosafos d.h. v'eina, writes that it is a standard cloth (maharsham says the term muzhav is a mistake and should say צבוע), but has sewn into it all sorts of precious stones, jewels and pearls. Being that the cloth is only there to help contain the precious stones, it is batul to the stones and doesn't qualify as a garment. This is why there is no problem of shatnez and it is also not susceptible to tu'mas nega'im. Tosafos apparently holds that even though the garment part of it is made like a regular garment that is spun and woven, and is soft, it would still not be a problem of shatnez since it is batul to the stones that are on it. Based on this, Rav Yitzchok Isaac Chaver (back of vilna shas) says that if one has a silver atara that is attached to a linen or even shatnez cloth, they may sew it on to their tallis and it will not be a violation of shatnez since the cloths is batul to the silver. Rav Moshe (dibros, heara 5, pg 376) wonders why this Tosafos isn't cited by the poskim. He assumes that even if this is what Tosafos means, since it isn't cited by the poskim, one cannot rely on this halacha l'ma'aseh.

The question that bothers me is, if the Aruch is correct that this head band is made from precious stones and metals, why would it not be a violation of עטרות כלות. It is one thing to permit head pieces made from materials, even if not just felt as Rashi describes, but once it will have precious stones (and Tosafos implies that gold is also sewn into it, even if the actual beged is not gold), it should be forbidden for a kalla to wear? Perhaps the rationale of R. Shimon for it not being a violation of the gezeira against crowns for brides is not based on how it is made but rather where on her head it is worn. Perhaps he holds that since it is worn below the head covering and not on the top of her head, it wouldn't qualify as a "crown" - וצריך עיון. Another possible explanation can be based on the Taz 361:6 who writes that the gezeira on crowns is only when they are made specifically for the bride. Based on this he permits using the silver crowns from the shul which was the custom in his time. Being that the איסטמא is not made for a bride, it would be permitted.

Shabbos 57a - Chatzitza That Doesn't Block Water

The gemara says a rule that whatever would be considered a chatzitza to prevent water from penetrating and therefore have to be removed before immersing in a mikva, would be forbidden to wear on shabbos out of fear that one may remove it and carry it. The gemara offers an איכא דאמרי which says that something that is dirty, although it allows water to penetrate is forbidden - כיון דטניפא, מקפד קפדא עלייהו - since it is dirty a person tends to be makpid and not want it there. The point of the gemara is to say that one may not wear such an item on shabbos in the public domain, but it isn't clear whether the gemara is insisting on the removal even for immersion in a mikvah.

Rashi explains that since water can easily penetrate there is no issue of chatzitza and one may immerse with this item. However, since it is dirty and by bathing with it on, the residue mud will get on a persons skin, they will definitely remove it prior to immersion and therefore forbidden to wear on shabbos for fear that they may carry it. However, Rashi citing his Rebbeim - רבותיו של רש"י, explain that even though water penetrates, one may not immerse in a mikva while they are wearing something that they are makpid about and don't want to be there. The רבותיו של רש"י create a new concept that even when something doesn't block the penetration of water, it can still be considered a chatzitza and must be removed for tevila. Although they write that this is when one is both makpid on it AND it covers the majority of one's body or hair, it would seem that just as by a real chatzitza the Rabbonon make a gezeira for anything that one is either makpid about OR covers the majority of their body, the rules here would be the same [this is the assumption of the pischei teshuva y.d. 198:4; whereas the Sidrei Tahara writes that the gezeira would only be extended to a case where one is makpid, even on part of their body, but not to a case of רובו שאינו מקפיד. Rav Moshe (dibros) even suggests the possibility that on this type of chatiztza there wouldn't be any gezeira at all and it would only be a problem if it were both רובו and מקפיד].

The Sha'ar HaTziyun 303:4 points out that the Rama seems to contradict himself. The Rama in Y.D. 198:4 writes like the רבותיו של רש"י that something can qualify as a chatzitza even if it doesn't prevent water from penetrating. Yet, in O.C. 303:1 the Rama explains this gemara like Rashi - something that is dirty even though it doesn't block water and doesn't need to be removed for tevilla would still be forbidden to wear on shabbos since practically speaking one will remove it before immersing to prevent the mud from getting on their skin. Why does the Rama in Y.D. assume like רבותיו של רש"י, yet in O.C. assumes like Rashi? If we were to say that the Rama is machmir in Y.D. like רבותיו של רש"י, but in Hilchos shabbos is machmir like Rashi, we could suggest that the Rama paskens like both l'chumra. However, it is difficult to see how the approach of Rashi could be a chumra and more restrictive than the approach of his rabbeim.

In general when we define the concept of מקפיד in the context of chatzitza for immersion we refer to anything a person wants removed during normal activity, either for their own sake or for the sake of the item. However, when Rashi describes the concept of makpid that will lead one to remove the item prior to immersion he is speaking about something that has some dry mud on it which one will remove before immersing to prevent themselves from getting dirty. It is possible that this type of makpid would not qualify as a chatzitza for mikvah. The definition of chatzitza for mikvah is something that in general one doesn't want to be there (either because it bothers them or they are afraid of it getting ruined) and therefore isn't batul to their hair or skin, but here she does want these woven threads to be there and isn't technically makpid about them even when she immerses, just that since it will leave some residue afterward she will remove it to prevent herself from getting dirty. It is not the woven material that she is makpid about, rather the mud that will get on her afterward, therefore the woven threads wouldn't be considered makpid and be batul to their hair (obviously, it is possible to argue on this assumption and consider even something that one will remove to prevent themselves from getting dirty when it gets wet to be considered makpid). According to this approach, something that is dirty on the inside and will leave behind a residue of mud on her skin, but isn't dirty on the outside, would qualify as makpid according to Rashi but not according to רבותיו של רש"י. Therefore, it is possible that although the Rama is machmir for רבותיו של רש"י in hilchos chatzitza, he still is machmir for Rashi's definition of makpid and cites Rashi's approach in hilchos shabbos to forbid wearing on shabbos even something that will leave behind some residue and therefore one will remove it before immersing even though in the halachos of chatzitza it wouldn't qualify as makpid so that they wouldn't be required to remove it (even according to רבותיו של רש"י who require things to be removed when water penetrates, that is only if it qualifies as makpid).

Shabbos 56a - Moreid B'malchus

The gemara says that the only thing that Dovid did wrong in the story with Bassheva and Uria is that he should have formally had Uria judged in Sanhedrin before killing him for rebelling against the king. The implication of the gemara is that even a moreid b'malchus must be judged by the Sanhedrin. Tosafos asks that the gemara in Megilla 14b implies that Dovid had the right to kill Naval for being moreid b'malchus by not providing him the food and supplies that he needed, even without judging him in a formal beis din. Why here does the gemara say that he should have judged Uria in the Sanhedrin? Tosafos answers that a Sanhedrin is required only to determine that the person has the status of a moreid b'malchus, but one doesn't need to follow the formal process of sleeping on the din and the regular scrutiny that a capital case would demand.

The Turei Even (Megilla 14b) asks that based on Tosafos approach, it is still difficult to understand how Dovid was able to kill Uria without following the procedure of Sanhedrin. Apparently, Tosafos considers one who is moreid b'malchus without being declared so by the Sanhedrin to be one who isn't deserving of capital punishment. Therefore, even though Uria was moreid b'malchus, it should have been murder to kill him. How can Dovid have done that?

In Maseches Makos and Baba Kama we find a distinction between penalty payments and compensation. When it comes to compensation the function of the beis din is to determine that the money is owed, but once determined it is owed retroactively. Whereas by penalty payments, the decision of beis din is actually what makes the person obligated to pay. Without Beis Din declaring the k'nas, it is not even owed. Similarly here, the Turei Even explains that the concept of the Sanhedrin determining that Uria was moreid b'malchus was like a monetary compensations, not like a penalty payment. It was merely a determination of the facts, but in truth he had status of moreid b'malchus because of his actions even without the formal declaration of the beis din. Therefore, Dovid failed to follow procedure, but since he knew that Uria was moreid b'malchus, he was considered to have that status even without a psak of the sanhedrin and therefore Dovid did not kill an innocent man.

Perhaps another approach to answer Tosafos question (this is another possible approach, not pshat in Tosafos) is that the function of the Sanhedrin is not to declare the person moreid b'malchus or even to verify that he is a moreid b'malchu. The king can make that decision without the Sanhedrin. However, if he is going to be killed b'yadayim by the Sanhedrin, they are only entitled to kill when they follow a standard process and procedure. Therefore, when it came to Naval who Dovid had to kill b'yadayim, he needed the process of a beis din. But when it came to Uria who Dovid was able to set up to be killed indirectly by putting him on the front lines, he didn't require a Sanhedrin. This approach is really the opposite of Tosafos. The purpose of the Sanhedrin is NOT to declare him a moreid b'malchus, it is necessary to follow the standard procedure of din if they are going to carry out capital punishment.

Shabbos 55b - Death and Suffering for No Reason

The gemara discusses whether we assume that there is a concept of מיתה בלא חטא and suffering without sin. Tosafos explains that אין מיתה בלא חטא means that Hashem can punish even for accidental violation. In other words, if we are to hold that there must be sin associated with death, that means that the bar of what is considered a sin has to be low to include even accidental violation. The gemara ultimately proves from a Braisa which says that there were 4 people (Amram - father of Moshe, Binyomin - son of Yaacov, Yishai - father of Dovid, Kela'eiv - son of Dovid) who died בעטיו של נחש, only because of the original sin committed by chava without having a sin of their own, that there can be death without sin. Therefore the gemara concludes - יש מיתה בלא חטא ויש יסורין בלא עון. Tosafos points out that even though we only prove the first part - יש מיתה בלא חטא, once we prove אין מיתה בלא חטא is wrong, we also assume אין יסורין בלא עון is also wrong.

This gemara seems to undermine the entire concept of reward and punishment. How are we to believe that one can be punished without doing any aveiros? Although Tosafos in Brachos 46b seems to take this more literally that there can be death and punishment without sin, the Meiri here has a different approach. The Meiri understands that the concept of reward for mitzvos and punishment for aveiros if מעיקרי הדת, a fundamental principal of our belief. Therefore, we definitely assume that there cannot be death or punishment without sin. Nevertheless, we consider these 4 people to have died only because of the sin of chava as a way of exaggerating their purity and minimizing the possible aveiros they may have committed. The bottom line according to the Meiri is that everyone must have sinned at some point and no one will ever be killed just for the sin of chava.

Shabbos 53b - Prohibition Against Refuah

One is not allowed to do things for medicinal purposes on shabbos because the gemara says that chazal made a decree that it will lead to שחיקת סממנין which is the grinding of the medicines and a violation of טוחן. However, the gemara concludes that there is some machlokes tana'im. Rashi explains that the machlokes is whether chazal forbade types of refuah that don't involve medicine out of concern that it will lead to grinding medicines. Rashi seems to understand that the gezeira of שחיקת סממנין all agree applies to both people and animals, but R. Oshiya holds that it doesn't apply to refuah that doesn't involve medicine such as soaking in a pool of water. However, the Ritva says that the nature of the machlokes is whether we make the gezeira only by people because they will do whatever necessary to heal themselves and will come to grinding, but not by animals since one doesn't get so nervous about his animals health. Being that we pasken like Rav Oshiya, there is a very practical distinction between Rashi and the Ritva whether we permit refuah for animals even using medicines, or whether we permit refuah for people when it doesn't involve medicine. The opinion of the Ritva is also that of the Rif and the Rosh which the M.B. 332:5 paskens  - we forbid all methods of healing for people but not for animals - ברפואת בהמתו אין אדם בהול כל כך שיבא לשחוק סממנים.

There is also a discussion regarding the nature of the gezeira that by permitting medicine one will come to grinding. The Eglei Tal (Tochen 37:7) writes that there are 3 approaches to this. 1. The Rif understands very simply that since one gets crazy over caring for their ailments and sicknesses, if we permit one to do forms of healing on shabbos they will be led to grind medicines. 2. Rashi seems to understand that if we permit refuah one will think that it is permitted to do tochen for the purpose of medicine. Meaning, rather than one accidentally coming to grind medicine because they are בהול about their refuah, they will think that the melacha of tochen is permitted. 3. The Eglei Tal offers an alternative approach to understanding this halacha. There are opinions in the Rishonim (teshuvas harashba and Ran) that Tochen follows the same rules as borer, so that if it is done immediately prior to the meal, it is permitted. The Rama 321:12 rules like this lenient opinion. Based on this the Eglei Tal explains that if we permit one to do things for refuah, they will come to equate refuah purposes with eating purposes and permit the act of grinding for refuah if it is done immediately prior to consumption. Therefore, chazal forbade refuah altogether in order to prevent people from equating refuah with eating purposes.

Shabbos 51b - Melting Ice On Shabbos

The gemara says that one can't crush ice in order to turn it into water. Rashi explains that the issur is that they are creating something new which is an issur d'rabonon since it resembles a melacha. But one may put it into a cup or plate, which rashi explains is referring to allowing ice to melt in a cup of wine. Rashi's approach to this gemara seems problematic because it begins with the assumption that there is a ma'aseh issur in crushing the ice, but then implies that if they would allow the ice to melt in an empty cup the resulting water would be assur even though no ma'aseh issur was done.

The Ran offers two approaches in explaining this gemara. The first approach is based on Rashi and Tosafos (not found in our tosafos) that the nature of the issur is a ma'aseh issur, therefore it is only forbidden to crush the ice but permitted to let the ice melt by itself. According to this approach there is no issur in the result or product, only in the act of crushing the ice to change its form. The Ran citing the Rambam follows the same approach, just that he considers the issur to be a subset of sechita, squeezing fruits that are meant for their liquid, rather than an issur of creating something new which isn't associated with any particular melacha. The Ran then offers an alternate approach in the name of the sefer hateruma who seems to understand that the ma'aseh isn't the problem, rather the result is the problem. Ice that transformed into water is muktzah since it is nolad on shabbos and didn't exist in that state before. According to this approach there is also a prohibition to do an act that changes the form, but the nature of the prohibition is the product or result, therefore one cannot do an act to yield that result. Based on this second approach it is prohibited to use the water that came from melting ice, and one cannot do something causing ice to melt or congealed fat to melt into a liquid form, such as putting it near heat or in the sun. The only heter in the gemara is when the ice melts into liquid that is already present so that the nolad product is never realized on its own.

The Shulchan Aruch (320) seems to follow the first approach and therefore only forbids active crushing of ice for the purpose of making water, but permits one to allow ice to melt. However, the implication of the shulchan aruch is that one can only use the melted ice when it melts into water or wine, which is problematic because if the S.A. follows the first approach the product should be permitted. Furthermore, the Shulchan Aruch in 318 clearly permits one to place congealed fat near a heat source in a way that it will melt implying both that it doesn't qualify as actively melting it and implying that the product is always permitted even if it isn't mixed into something else. Therefore, the Shulchan Aruch in 320 that permits ice that melts into wine or water, would hold that even ice that melts into an empty cup would be permitted following the first approach, but chooses a more common case such as melting ice into a drink rather than into an empty cup. This would also seem to be the approach of Rashi that the nature of the issur is the ma'aseh issur, not the resulting product. Rashi explains that one can melt ice into a cup referring to a cup that contains water or wine simply because that is the more common case. This seems clear from the fact that Rashi says בימות החמה, he seems to be focusing on the fact that it is summer and therefore the wine wouldn't taste good unless it is cooled down with some ice. But really both rashi and the shulchan aruch would permit one to place ice in an empty cup, put it near a heat source and drink the water.

The Rama (318) on the other hand writes ויש מחמירין implying that one should be machmir like the sefer hateruma. Even if there is gravy into which the congealed fat will melt, the Rama holds that one must be machmir since the melted fat will sit on top of the liquid gravy and be considered nolad which is muktzah. According to this approach any frozen or congealed item that changed form and is recognizable as an entity without being mixed into something would be forbidden to use and since it's forbidden to use it is also forbidden to make. Therefore, one cannot use the water that results from ice melting in an empty cup.

The opinion of the sefer hateruma who considers the problem to be in the product and not the action would seem to result in a leniency. Is one allowed to actively crush ice causing it to melt in a cup of wine? The first approach (shulchan aruch) would consider this to be an act of molid or sechita and therefore be assur, but the second approach (rama) would hold that since the result is immediately mixed in with the wine, it isn't a nolad problem and therefore permitted. However, it seems that the Rama is machmir for the sefer hateruma, but doesn't pasken like the sefer hateruma against the first approach, and would therefore admit that it is assur.

It would also seem that according to the sefer hateruma that the rama is machmir for one would not be able to make ice on shabbos either. Since the nature of the issur is the product being muktzah, there should be no difference between the melting of ice or the freezing of water. In both situations the product should be muktzah and therefore assur to cause.

Shabbos 51a - Adam Choshuv

In my shiur this morning, I pointed out that although Rav Moshe has a teshuva explaining that ma'aris ayin only applies to situations where one is doing something that is mutar, but other people think he is doing something else which is actually assur. For example, one who hangs out soaking laundry to dry on shabbos, and people think he laundered them on shabbos, that is ma'aris ayin. But if one were to put out their laundry to dry and people will think he violated shabbos because of their mistake in thinking that drying laundry is also prohibited on shabbos, that is not considered ma'aris ayin. Nevertheless, it seems from our gemara that even if one is doing something that is mutar and other people will mistakenly think it is assur, an adam choshuv should refrain from doing it as rashi explains - שהרואה אותו שהוא מיקל עומד ומיקל יותר. In the case Rav Moshe was describing the sho'el was giving him mussar for driving to shul on friday afternoon after candle lighting since some people think it's assur. After rejecting the problem, Rav Moshe agreed to stop this practice but didn't explain why he agreed. Perhaps he is relying on this gemara.

I later realized that I had written about this about 5 years ago:

http://hearos.blogspot.com/2007/03/moed-kattan-12b-adam-chashuv.html

Shabbos 51a - Wrapping to Keep Warm

The gemara says that one can wrap something that is cold - מותר להטמין את הצונן. Rashi explains that this means that one can wrap something cold to maintain the cold temperature but cannot wrap something cold to warm it and remove the chill. According to Rashi the gemara is coming to exclude the possible prohibition against wrapping to keep cold because it may lead to wrapping to keep warm, and wrapping for warmth is always prohibited. The Ran quotes the Rambam as saying that as long as one is not wrapping in something which increases heat, one may even wrap something cold so that it doesn't get colder or to even remove the chill.

The gemara discusses the case of wrapping something after it was transferred from the kli rishon into another container. The Rambam understands that once something is in a kli sheini there is no prohibition of hatmana. The Rambam understands that just as one may wrap something that is cold because there is no expectation of it really being warm and won't lead to reheating, so too one may wrap something once it has been put in a kli sheini. However, The Ran explains that Rashi cannot permit wrapping a kli sheini. Rashi holds that even if something is cold it cannot be wrapped to remove the chill, certainly one cannot wrap a hot food that is in a kli sheini. Therefore, Rashi goes li'shitaso in explaining the leniency of פינה ממיחם למיחם to be that since one poured from the kli rishon to the kli sheini for the purpose of cooling it down, there is no concern that they will want it so hot. We permit them to wrap it and aren't concerned that they will not be content with the level of warmth and come to reheat it, since they had already done something for the purpose of cooling it down. According to Rashi, we don't permit the wrapping of a kli sheini unless the item was put in a kli sheini for the purpose of cooling down. Based on Rashi, if one poured hot water into a thermos because it is better insulated and will retain the warmth more, although the actual thermos isn't a violation of hatmana, one would not be allowed to wrap the thermos and insulate it more since the pouring into a thermos was with the intent of preserving the warmth and not cooling it down.
Even according to those who permit the wrapping of a keli sheini (when not put in the keli sheini specifically to cool down - rambam), that would not necessarily allow the wrapping using a kli sheini. In the gemara 40b Rav Yitzchok Bar Avdimi wanted to place a jug of oil into the hot bath, and Rebbi instructed him to take water in a kli sheini and immerse the oil in that. This implies that there is no issue of hatmana by warming something up when a kli sheini is used as the heat source. However, the Gra"z (257:10) asks on this gemara why isn't there a problem of hatmana. It could be that Rebbi was not permitting the jug of oil to be submerged in the kli sheini (which would answer at least according to those rishonim who hold a partial hatmana is permitted such as the Rama 253). However, the Chazon Ish (37:32) writes that heating up a bottle or jar by surrounding it with warm water doesn't qualify as hatmana. According to the first approach, when heating up a baby bottle in water that was put into a kli sheini one must be careful, whereas according to the chazon ish that would not qualify as hatmana at all.

Tosafos Yeshanim holds that the heter of פינה ממיחם למיחם may be better than something cold. When one empties from a kli rishon into a kli sheini for the purpose of cooling it down, even if it is still very hot, they have shown that the heat isn't significant for them and therefore it is permitted to wrap it to preserve heat. But an item which is cold may still be prohibited to wrap to remove the chill, as Rashi explains, since they didn't do anything to show that they want it to be cold. Nevertheless, Rav Moshe (Igros, O.C. 1:95) explains that Tosafos Yeshanim understands that the gemara permits one to wrap something which is cold even for the purpose of removing the chill like those who argue on Rashi, yet permit פינה ממיחם למיחם only when it was poured into the kli sheini for the distinct purpose of cooling it down as Rashi explained.
Although the gemara concludes that it is permitted to wrap something cold, there is a machlokes amoraim whether an adam chashuv should be machmir. Rav Moshe (dibros #25) points out that according to the Rambam where the purpose of wrapping is to remove the chill, it makes sense that an adam choshuv should be machmir since the wrapping to remove the chill can lead one to wrap even for heat. But according to Rashi who holds that the nature of wrapping is to preserve the cold, it makes very little sense to be machmir for an adam choshuv because it essentially give the wrong impression as to the nature of this issur d'rabonon. It is one thing for an adam choshuv to be machmir for things that are in line with the halacha, but it doesn't make sense to be machmir for things that would mislead others as to what the exact nature of the halacha is.
Another two issues that are related to this is whether one can do hatmana when the ultimate temperature will remain below yad soledes. The Magen Avrohom has a safeik whether one can wrap something that has cooled to below yad soledes in order to preserve some level of heat. However, the M.B. 257:29 paskens like the gra"z and pri megadim who are lenient. In the Sha'ar HaTziyun (29) he writes that this is dependent on the machlokes shulchan aruch and rama in 318 whether there is bishul to reheat something that has dropped below yad soledes, where we see that according to the Rama even below yad soledes qualifies as חמין and therefore would be assur to do hatmana. The Chazon Ish (37:31) disagrees, even the Rama understands that below yad soledes is not called chamin, but regarding reheating we are lenient on anything that is recognizable that it had once been hot i.e. it hasn't cooled down completely. But this is only when one is wrapping something on shabbos that is below yad soledes to preserve its heat. If one is wrapping something cold to increase its heat, even if it can't reach a temperature of yad soledes, the Biur Halacha 257:6 d.h. afilu cites the Gr"a who says that this is forbidden to do on shabbos (therefore, wrapping a baby bottle with milk in hot water even in a kli sheini and even when it can't get to yad soledes, would be assur).

Shabbos 50b - P'sik Reisha

The gemara cites a mishna that permits a Nazir to wash his hair with something that may cause hair to be pulled out which would be a violation of his nezirus, since it is a davar sh'eino miskavein. The gemara assumes that this Mishna was authored by R. Shimon who permits a davar she'eino miskavein, otherwise it would be forbidden. Yet, the Mishna concludes that he may not comb his hair. Rashi explains that the reason he can't comb his hair is because it will inevitably pull out hair and even R. Shimon admits that if it is a p'sik reisha it is forbidden. Rashi repeats this point later on 81b more clearly. Tosafos disagrees and says that the reason a Nazir cannot comb his hair, the gemara in Nazir 42a explains is because he intends to pull out the loose hairs. Unlike Rashi who considers it a davar sh'eino miskavein, just that it is a psik reisha and therefore forbidden, Tosafos considers it a davar hamiskavein since he intends to pull out the loose hairs. [The Ritva tries to bring Rashi and Tosafos together by saying that it is not truly a davar hamiskavein, but since it is a pesik reisha, it is like he is intending to do it and qualifies as a davar hamiskavein]. To explain how Rashi fits with the gemara in Nazir, the Keren Orah writes that by combing his intent is not to pull out hairs but to separate the clumps of hairs which is a pesik reisha that it will pull hairs out. Therefore, although the gemara focuses on kavana, the real problem is because it is a pesik reisha that it will pull out hairs.

The Milo Ha'roim (back of vilna gemara) suggests that the machlokes may be dependent on the machlokes between the Terumas HaDeshen and Magen Avrohom (314:5) whether a pesik reisha is permitted on an issur d'rabonon. Being that pulling out hairs would presumably only be a Rabbinic violation of gozeiz (shearing), Rashi may hold like the Magen Avrohom that a pesik reisha on a d'rabonon is prohibited so that would be enough to explain why combing would not be allowed, whereas Tosafos would hold like the Terumas Hadeshen that is is permitted and therefore would not be enough to explain why it is forbidden, therefore they need to say it is because it's a davar hamiskavein. The discussion is based on the Shulchan Aruch who permits the removal of a knife from a barrel in a way where it will inevitably cause the hole to widen. The Shulchan Aruch based on Terumas Hadeshen permits it even if it's a pesik reisha since the making of the hole is only an issur d'rabonon, whereas the Rama says that it is only permitted if it is not a pesik reisha. The M.B. (11) cites many achronim who side with the Magen Avrohom and hold that a pesik reisha is forbidden even on an issur d'rabonon.

Even those who forbid a pesik reisha on an issur d'rabonon, may permit it to be done by a goy. The Mishna Berura (253:51) forbids one to remove a pot from coals that surround it when it will inevitably stir up the coals, extinguishing the upper ones and lighting the lower ones. Even though some forbid it to even be done by a goy, the M.B. says that for a shabbos need one may rely on those who are lenient. The Sha'ar HaTziyun (43) explains that it is pesik reisha that one doesn't really care about on an issur which is only d'rabonon, therefore it can be done by a goy. Even the Magen Avrohom would permit this. The implication is that a pesik reisha on an issur d'oraysa cannot be done by a goy. However, the M.B. (253:99) permits one to allow a goy to put a pot near  heater even though it will cook when he later lights the heater to warm up the house. The rationale is that we permit amirah l'nachri on a pesik reisha, implying that even a pseik reisha that one actually cares about and wants, and even on an issur d'oraysa, we permit it to be done by a goy. It is difficult to reconcile these two pesakim with one another, unless the M.B. is relying on the opinions who don't consider reheating a liquid to be an issur d'oraysa so that it would be a pesik reisha on a d'rabonon (which the terumas hadeshen even permits to be done by a Jew).

Shabbos 49a - Sleeping in Tefillin

The gemara says that one should not put on tefillin unless they can uphold it's kedusha like elisha ba'al kinafayim. Abaye says that it refers to the ability to stay awake without a concern of dozing in the tefillin, and Rava says that it refers to the ability to maintain the cleanliness of one's body and not pass gas while wearing tefillin. Tosafos explains that it is incorrect to assume that one must be on the level of elisha ba'al kinafayim in any respect, except to maintain a clean body. Therefore, Tosafos bemoans the fact that people are reluctant to put on tefillin and justify their practice by saying that they aren't on the level of elisha ba'al kinafayim.

It is unclear from the opinions of Abaye and Rava which one of the two is more restrictive and which is more permissive. Rashi explains that the concern of falling asleep is really a concern of passing gas in the tefillin, but Rava holds that so long as one can be careful not to fall asleep, we are confident that he can hold himself back from passing gas while awake. Abaye on the other hand is concerned that he won't be able to control himself even while awake, therefore if he is concerned that he may pass gas, he shouldn't put on tefillin. According to Rashi it seems that Rava is more permissive than Abaye.

However, Tosafos understands that Abaye is only concerned for one who is concerned for passing gas, but isn't concerned that someone will fall asleep in inadvertently pass gass, whereas Rava holds that one who is tired and concerned he may fall asleep should also not put on tefillin.

In trying to explain the problem of sleeping with tefillin, both Rashi and Tosafos mention the concern of passing gas, but they each mention a second concern which seems to be rejected by each other. Rashi says that there is a concern that he will see a seminal discharge, which Tosafos explicitly rejects based on a gemara in Succah. Tosafos mentions the concern of a hesech hada'as, mental distraction from the tefillin, which Rashi doesn't mention.

Tosafos is apparently trying to deal with an obvious question. We are aware that there is a prohibition to have a היסח הדעת while wearing tefillin which the gemara learns out from the tzitz. Why then don't we simply say that the problem with sleeping in tefillin is an inherent problem of he'sech ha'daas rather than a concern that he will pass gas? To deal with this question Tosafos says both reasons (see also ohr zarua cited in biur halacha 44 who also cites both reasons). However, the question still stands according to Rashi?

The Rishonim, cited by M.B. 44:3 explain that the definition of היסח הדעת in regard to the mitzvah of tefillin does NOT mean that one needs complete concentration on their tefillin for the duration of time that they are wearing it. Tefillin is a mitzvah that applies all day and therefore one is allowed to to mundane activities and non-kodesh work while wearing tefillin, even though they will not be thinking about the tefillin. The issur of a היסח הדעת in the tefillin is merely to the exclusion of קלות ראש, light headed and inappropriate silly behavior. According to this approach, it seems difficult that the source of this halacha is the tzitz. Would we say by the tzitz as well that the entire prohibition is only against lightheaded behavior. It would seem that the obligation while wearing the tzitz would be not to have any hesech ha'daas from kodesh things at all.

The Sha'agas Aryeh (39) discusses the nature of hesech hada'as in tefillin and concludes that even a hesech hada'as that isn't a קלות ראש can still qualify as a hesech hadaas, against the Rishonim that are quoted in the Mishna Berura.

מענין לענין - The Rambam only paskens the issur of hesech hada'as in hilchos tefillin 4:14, but doesn't make any mention of it in hilchos klei hamikdash. However, in Hilchos Tefillin the Rambam does write that the source of the issur of hesech hada'as in tefillin is from the tzitz. Why does he not mention it in Hilchos Klei HaMikdash? The Minchas Chinuch 99 makes the point, but doesn't deal with the question.

Shabbos 48a - Cooking Something Edible Raw

Tosafos discusses whether one is allowed to leave a pot with raw apples cooking on a fire before shabbos. Tosafos suggests that since one is allowed to do shehiya and leave a pot cooking on a fire once it is a third of the way cooked, כמאכל בן דרוסאי, without a concern that he will stir the flames, one can also leave the pot with apples cooking since it is even more edible than food which has reached מאכל בן דרוסאי.

It is possible that the rationale of Tosafos is that just as when something reaches כמאכל בן דרוסאי it is considered cooked and therefore we aren't concerned that he will stir the coals to cook it more, similarly something that is edible without being cooked is considered halachically cooked so that the stirring of the coals is not a concern. However, this clearly isn't the opinion of Tosafos. In the very next discussion Tosafos forbids one to wrap on shabbos the pot containing the apples because it would be a violation of cooking. Tosafos clearly considers there to be a violation of cooking even on food that is edible without cooking. Therefore, when Tosafos permits shehiya on the pot containing the apples, their rationale is that although we don't consider it cooked, he won't be motivated to stir the coals since he doesn't care that much about it being cooked. This is to the exclusion of the opinion of the Rambam (9:3) who holds that there is no Torah prohibition to cook things which are edible raw.

Rav Moshe (Dibros, # 4) points out that according to this approach we can prove from Tosafos that they do not consider כמאכל בן דרוסאי  to be considered cooked. Had Tosafos held that כמאכל בן דרוסאי is considered cooked on a Torah level so that any further cooking wouldn't constitute a violation, there would be no similarity or proof from מאכל בן דרוסאי to a food edible raw since Tosafos clearly holds that by a food edible raw there is a violation of cooking. How then can Tosafos prove that we can leave the pot of apples on the fire from the right to leave the pot that has been cooked כמאכל בן דרוסאי on the fire; perhaps we only permit כמאכל בן דרוסאי because it is considered already cooked. Clearly, Tosafos must be assuming that there would be a violation of cooking both by a food edible raw and by a food that is כמאכל בן דרוסאי, therefore just as by מאכל בן דרוסאי we aren't concerned that he will stir the coals, the same will be true with a food that has already been cooked. Based on this, Rav Moshe points out that Tosafos here contradicts Tosafos at the beginning of perek kirah who holds that once something is כמאכל בן דרוסאי it is considered cooked m'doraysa and there wouldn't be any torah violation in cooking it more.

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Tosafos writes (end of d.h. mai) that we do not permit someone to place a kettle of water in a place where it can reach a temperature of yad soledes bo, even if their intent is to remove the kettle from being near a heat source prior to it reaching the temperature of yad soledes. However, in the question when Tosafos suggests this distinction, rather than using the term דלמא משתלי - lest one forget, Tosafos uses the phrase דשמא יבא לטעות ויניח שם עד שיתבשל. The Eglei Tal asks on Tosafos why are we concerned when someone puts a kettle of water near the fire where it can potentially reach yad soledes out of fear that he may forget; forgetting would not qualify as a מלאכת מחשבת and it wouldn't be an issur d'oraysa so why should we make a gezeira that he may forget since even if he does it will only be an issur d'rabonon? It seems to me that the way Tosafos articulated the concern in the question, avoids the question of the Eglei Tal. If one would forget the pot of water on the fire and it would reach yad soledes, the inadvertent act of cooking would not qualify as a מלאכת מחשבת and it would not be an issur d'oraysa. That is why Tosafos at first doesn't say that one may forget it, rather that one would make a mistake and leave it there. Perhaps Tosafos is trying to say that we are not concerned for him forgetting, rather we are concerned that he will make a mistake in halacha and think that it is permissible to leave it to heat up even if it is not on the fire. A mistake in halacha would certainly qualify as a מלאכת מחשבת and constitute an issur d'oraysa.

Rav Moshe approaches Tosafos from the exact opposite perspective of the Eglei Tal. Rav Moshe (Dibros #5) asks, why is Tosafos only concerned that he may forget the pot or come to make a mistake, implying that the entire problem with placing the pot near the fire when he intends to remove it is only a Rabbinic violation and not a Torah violation. Rav Moshe asks that given the nature of the melacha of cooking, it is similar to planting. The issur is violated by setting up a situation where something can cook. The requirement to actually cook is merely a condition, so that if it somehow is removed prematurely the person would retroactively not have violated the issur. However, if they would "forget" it there, even though it is completely inadvertent, they would be in violation of a Torah prohibition of cooking. Therefore, even if we weren't concerned that he would actually forget the pot near the fire, we couldn't permit doing an act that is an issur d'oraysa just because he plans on making sure the condition isn't fulfilled. Rashi 40b implies that one can actually leave water near a fire to remove the chill so long as he plans on removing it before it reaches yad soledes. Rav Moshe's asks that Rashi implies that it isn't even an issur d'rabonon, but really it should even be an issur d'oraysa!

Shabbos 45a - Set Aside for the Mitzvah

The gemara has a concept that something which is set aside for the mitzvah, becomes muktzah for the duration of the time it is being used for the mitzvah. The two examples that the gemara speaks about are Succah decorations and Shabbos candles. Rashi explains that the rule is the same - so long as the mitzvah is still applicable they are muktzah, but afterwards they are permitted to be used. Therefore, a succah is forbidden to be used for other purposes for the duration of Succos since that is the time of its mitzvah, whereas the oil of the Shabbos candles are not allowed to be used (even according to Rav Shimon) for the duration of the time that the candles are burning. Tosafos explains even the oil that would squirt out from the candle would be forbidden to use during the time the candles are burning because that too was set aside for the mitzvah. But, after the flame goes out, the mitzvah is over and the oil may be used.

There is a Sh'iltos d'rav Achai Goan in Parshas Vayishlach that says that on the last day of chanuka if there is left over oil in the candles, one must make a fire and burn the oil. The Sh'iltos forbids the use of the oil for personal use because it was set aside for the mitzvah. Tosafos 44a d.h. she'bner, asks why Chanukah candles are different than Shabbos candles? Why is it that for Shabbos candles, when they go out we consider the mitzvah to be over and the oil is permitted, whereas by Chanuka candles even after Chanukah ends the oil is not permitted to use?

To answer this question, Tosafos makes a distinction between Shabbos candles and Chanuka candles. However, Tosafos is a little confusing because they mention two seemingly independent points in their distinction. Tosafos writes that Chanuka candles are not for one's personal benefit, rather to publicize the miracle, therefore one doesn't anticipate them extinguishing early and expect to use the oil. On the other hand, Shabbos candles are primarily there for the purpose of receiving benefit so that one is anticipating them going out and using the oil. Tosasfos seems to focus on two separate points: 1. Shabbos candles are permitted to benefit from whereas Chanuka candles aren't. 2. For shabbos candles one anticipates and hopes for them to go out sooner, whereas Chanuka candles which are there to publicize the great miracle, one wants to fully give over to the mitzvah. Rav Moshe (Dibros 38) writes that he doesn't understand why Tosafos had to mention the יושב ומצפה  aspect at all. The distinction is quite simple. The halacha of the oil is the same as the use of the candle. Since Shabbos candles can be used, their left over oil can be used (just as food which is designated for the mitzvah of oneg shabbos can be used for mundane enjoyment since it is fundamentally for the purpose of deriving benefit). But since Chanuka candles is off limits from being used for any benefit, their oil cannot be used. If this were Tosafos' intent, they wouldn't have to focus on the fact that Chanuka is for publicizing the miracle and therefore one is not יושב ומצפה for them to go out. Rav Moshe leaves with at צריך עיון and doesn't understand why Tosafos has to make a big deal about the Chanuka candles being parsumei nissa, representing the miracle and wholeheartedly given over for the mitzvah?

I think that Tosafos considers the distinction Rav Moshe makes to be insufficient. The rule is as we find by a succah, after the mitzvah ends the left over material can be used. Even mitzvos which are not there for the purpose of deriving benefit, such as the mitzvah of succah, would be permitted to be used for mundane benefit after the mitzvah is over. Therefore, to simply distinguish between shabbos and chanuka based on whether the mitzvah is designed for one to benefit from, is not enough. Therefore, Tosafos is forced to explain that Chanuka is special. Since the mitzvah is there to publicize a miracle, one is happy to fully give over all the materials for the mitzvah without any anticipation of being able to use them. That is why even after the mitzvah is over, the materials remain assur. No other mitzvah would be like this, not even a mitzvah from which one cannot benefit during the mitzvah.

The Ritva (21b) writes that the prohibition to use the light of the Chanuka candles is technically only during the half hour that they need to be burning for. After the half hour it is technically permitted to even benefit from the light, just that we don't allow you to actually benefit from the light because of בזוי מצוה. However, the material is no longer considered to be connected to the mitzvah, therefore if it goes out, the mitzvah for that night is over and one is allowed to benefit from the oil. It is not like Succah where we consider the full 7 days to be one long mitzvah, rather the lighting of each night is independent. Therefore the Ritva rejects the sh'iltos who holds that after Chanuka one must burn all the oil. The Ritva permits the use of the left over oil even during chanuka, and even on that night (the ritva implies that according to the Rif even if it goes out early one can benefit from the oil, but the beis  yosef 677 holds that only if it burned for its full time).

Shabbos 44a - Tiltul Min HaTzad

The gemara concludes that טלטול מן הצד is considered normal moving of muktzah and cannot be done on shabbos. Tosafos explains that there are other sources that imply that one can move muktzah through tiltul min hatzad, therefore Tosafos concludes that it depends on the purpose. If one is doing טלטול מן הצד for the sake of moving the actual muktzah item from one place to another such as by a corpse, that is not allowed. But if one is doing the טלטול מן הצד for the sake of a non-muktzah item, just that the muktzah gets pulled along with it, that is permissible. This distinction is paskened in Shulchan Aruch. In siman 311:1 the Shulchan Aruch writes that tiltul min hatzad for the sake of the muktzah is prohibited (unless it is a special circumstance for kavod ha'meis), but in 311:8 the Shulchan Aruch paskens that tiltul min hatzad for the sake of something permitted where the muktzah will inadvertently be moved, is permitted. Based on this, the Mishna Berura (6) writes that one may not take a non-muktzah item and use it to push muktzah because that would be טלטול מן הצד לצורך דבר האסור, which would be a violation of moving muktzah. However, if one is doing so because they need to use the place where the muktzah is sitting, it is permitted. Therefore, the M.B. (308:115) paskens that if one has shells on a table (assuming that it doesn't make the area look disgusting so that there is no heter based on גרף של רעי), since they are muktzah, he cannot move them with his hand. But one can take a napkin and sweep them away if he needs to use the place since that would qualify as tiltul min hatzad for the sake of something permitted.

The gemara paskens like R. Yehuda that if a fire breaks out in a house where there is a corpse, one may move the corpse away from the fire because chazal were concerned that if they didn't allow it, one would come to intentionally (Tosafos) extinguish the fire. The Ran cites a machlokes whether we only allow the moving of a corpse when it is טלטול מן הצד, even though it is normally forbidden, we allow it to be done to prevent extinguishing a fire, or do we even allow the direct moving of a corpse to save it from a fire. It seems from Tosafos that when it is not possible to move the corpse through a ככר או תינוק, or move it מן הצד, we allow the direct moving of the corpse. Tosafos writes that the fact that the gemara suggests that everyone holds that טלטול מן הצד is a problem, when it could have said the opposite, implies that we pasken that טלטול מן הצד (at least for the purpose of moving muktzah) is prohibited. Tosafos suggests that it could have said the opposite and made the אוקמתא to be when there is not ככר או תינוק and no beds so that it can't be moved with טלטול מן הצד. It seems that even if טלטול מן הצד wasn't possible, Tosafos assumes that R. Yehuda would still permit the direct moving of a corpse to save it from a fire. This is exactly what the Shulchan Aruch 311:1 paskens. Ideally, a corpse should be moved using a ככר או תינוק, if that's not possible then מן הצד and if that's not possible then it can be moved directly.

Shabbos 42b - Klei Sheini on Shabbos

The mishna says that spices cannot be put into a kli rishon even after it is removed from the fire because it will cook, but can be put into a kli sheini because they cannot get cooked in a kli sheini. There is a contradicitonin diyukim of the reisha and seifa of the mishna whether pouring from a kli rishon (iruy) is treated like a kli rishon or like a kli sheini. Tosafos tries to prove both directions and concludes that pouring from a kli rishon cooks the outer layer - כדי קליפה.

There is a gemara earlier 39a that says that one can only put into hot water, something that has already been in hot water prior to shabbos, otherwise it would be a violation of cooking. It is unclear whether that gemara is speaking about a kli rishon or a kli sheini. Tosafos explains that since the gemara allows pouring from whatever type of kli we are speaking about onto the food, it comes out that according to those who consider pouring from a kli rishon not to qualify as cooking, we can be speaking about a kli rishon. Meaning, one can pour from a kli rishon onto the food, so long as they don't soak the food in a kli rishon. However, if we consider pouring from a kli rishon to be cooking, we must be speaking there about a kli sheini. Therefore, according to Rabbeinu Tam who considers iruy of a kli rishon to be cooking, the braisa is speaking about a kli sheini and prohibits the soaking of a food that hasn't been put into a kli sheini before shabbos. Based on this Tosafos writes that one cannot cook an uncooked food in a kli sheini, because the water is hot and it looks like you are cooking. Tosafos says that to reconcile this with our mishna we are forced to say that most foods cannot be put into a hot kli sheini, but spices are an exception because the מחזי כמבשל doesn't apply to them since their function is just to give taste to the food. In addition to the מחזי כמבשל problem of a kli sheini, the M.B. 318:42 explains the Shulchan Aruch who says that bread cannot be put into a hot kli sheini because there are things that are easily cooked which can be cooked even in a kli sheini. Since we aren't such experts as to what qualifies, we are machmir for everything. The Sha'ar Hatziyun (68) points out that the exception is water and oil, which are explicit in the gemara that they don't get cooked in a kli sheini. Oil is clear from the gemara 40b and water from the gemara 42a. Obviously, spices are also an exception.

The Chayei Adam (Hil. Shabbos 20:4) has a famous opinion that if the water in the kli sheini is יד נכוית בותת, hot enough to burn one's hand, it has the ability to cook, even in a kli sheini. The M.B. (48) quotes the chayei adam without citing anyone who argues. Rav Moshe (Igros, O.C. 4,74,4) writes that it doesn't make that much of a difference for us because we are machmir for almost all foods to consider them מקלי הבישול - easily cooked, and therefore we don't put raw foods into a kli sheini even if it is yad soledes bo. However, it would make a difference for water, oil and spices that even we are lenient to put in a kli sheini. Based on the gemara 42a it would be permissible for one to add a drop of tap water to their hot water in a kli sheini and not worry about the water being cooked. However, the Chayei Adam would forbid adding water to a kli sheini that is יד נכוית בו, and therefore wouldn't allow if if the water were too hot.

The Chayei Adam refers us to his sefer Sha'arei Tzedek (perek 2,28, Binas Adam 9) where he cites the Rambam (Hil. Ma'asros 3,15) who says that if the kli sheini is יד נכוית בו, there is cooking even in a kli sheini. He also cites the the Tur regarding an אמבטי based on the gemara 42a, and explains that there is a source for this in the yerushalmi in ma'asros.

It seems to me that Rashi 42a d.h. b'kos, would be a support for the chayei adam. Rashi explains that the reason that cold water can be added to a cup, which is a kli sheini, is because it isn't that hot, implying that if it were too hot, one could not add water. But, even Rashi quotes a second approach that implies so long as it is a kli sheini, it is not a problem. Furthermore, the Mishna 42a that distinguishes between a kli rishon and kli sheini implies that spices can be put in a kli sheini even if it is רותחין, because that is the type of kli rishon we are speaking about as well. The Ritva writes explicitly that even if the kli sheini is רותח it doesn't have the ability to cook. The rationale for a kli sheini not being able to cook is as Tosafos explains 40b that it doesn't have the heat radiating from it's walls to maintain the temperature. Therefore, it seems clear that in Hilchos Shabbos we don't regard a kli sheini as being able to cook things that aren't מקלי הבישול, just that we are machmir for most foods that they are מקלי הבישול or that it looks as if one is cooking. But, water, oil and spices can be added to a kli sheini no matter how hot it is.

Regarding the Tur that the Chayei Adam cites who speaks about the prohibition to add water to an אמבטי even though it is a kli shein, because it is very hot; that is not a question at all. Tosafos 42a d.h. aval, also considers an ambati to be a kli sheini (unlike the implication of rashi that ambati is a kli rishon and sapal is a kli sheini), but clearly writes the distinction between a כוס to which cold water can be added and a אמבטי to which cold water cannot be added, is not temperature. Rather, the distinction is that an אמבטי which regularly has very hot water, looks like a kli rishon to that people will think it's a kli rishon, whereas a cup of hot water everyone knows is a kli sheini. Therefore, Tosafos also indicates clearly that tap water can be added to a cup of steaming hot water (or tea) in a kli sheini and will not constitute cooking.