- Four different reasons the Rabbanon prohibited immersing keilim on Shabbos and Yom Tov
The Mishnah on Daf 17b stated: חל להיות אחר השבת – If Yom Tov fell after Shabbos, Beis Shammai say: מטבילין את הכל מלפני השבת – We must immerse everything before Shabbos, but Beis Hillel say: כלים מלפני השבת ואדם בשבת – Keilim must be immersed before Shabbos, but a person may immerse on Shabbos. The Gemara notes that both Beis Shammai and Beis Hillel agree that the Rabbanon banned immersing tamei keilim on Shabbos and asks the reason why. Rabbah said: גזרה שמא יטלנו בידו ויעבירנו ארבע אמות ברשות הרבים – It is a decree out of concern that one might take the kli in his hand and transport it dalet amos in reshus harabim. Rav Yosef said גזרה משום סחיטה – It is a gezeirah lest one come to do the melachah of סחיטה - wringing wet clothing. Rav Bivi says: גזרה משום ישהא – It is a gezeirah to prevent against the possibility that one might delay immersing his keilim until Yom Tov when he has more time. Rashi explains that in the interim, the keilim might come in contact with terumah and be metamei it. Rava says מפני שנראה כמתקן כלי – because it is similar to making a kli usable.
- Why a person is permitted to immerse, even on Yom Kippur
The Gemara objects to Rava’s reason that the Rabbanon prohibited immersing keilim on Shabbos and Yom Tov מפני שנראה כמתקן כלי – because it is similar to making a kli usable. If so, a tamei person should also be prohibited from immersing himself, since he appears to be “repaired” by this immersion. The Gemara answers, אדם נראה כמיקר – A person who immerses himself in a mikveh appears to be cooling himself. His true motive – to render himself tahor – is not readily apparent and therefore does not appear to be a form of repair. The Gemara says that this explains why an immersion on Shabbos would be permitted, but why would an immersion on Yom Kippur be permitted? Since bathing on Yom Kippur is forbidden, it would be obvious that he is immersing to get rid of tumah, and should therefore be prohibited according to Rava, because it is similar to repairing. Rava said: Is there anything pertaining to melachah that is permitted on Shabbos and prohibited on Yom Kippur? אלא הואיל ובשבת שרי ביום הכפורים נמי שרי – Rather, since it is permitted to immerse on Shabbos, it is permitted on Yom Kippur as well. The Gemara will question whether Rava holds of the principle of הואיל – “since” an act is permitted in one case, it must be permitted elsewhere as well.
- ושוין שמשיקין את המים אבל לא מטבילין
The Mishnah on Daf 17b stated: ושוין שמשיקין את המים בכלי אבן לטהרן אבל לא מטבילין – Beis Shammai and Beis Hillel agree that we may make tamei water contiguous to the waters of a mikveh in a stone kli to be metaher them, but we should not immerse this tamei water. Rashi explains that the Mishnah discusses a person whose drinkable water was tamei and he needed to purify it. The water of the mikveh could not be used for drinking because it was not fit for consumption. The act of השקה, making the waters contiguous, serves to fuse them into a single entity of mikveh water, analogous to planting seeds in the ground, and frees them of tumah. The Gemara here asks, what does the Mishnah mean when it says לא מטבילין – we should not immerse? Shmuel explained אין מטבילין את הכלי על גב מימיו לטהרו ביום טוב – We may not immerse a tamei kli by way of its water, to be metaher it on Yom Tov. This is why using a stone kli is required, since stone keiliim cannot become tamei.