1) ENTERING A BATHROOM WHILE WEARING TEFILIN OR A KAMEI'A
QUESTION: The Gemara suggests that a person is permitted to walk into a bathroom while wearing a Kamei'a that is covered in leather. The Gemara adds that if not for the letter "Shin" inscribed on the outside of Tefilin, one would be permitted to walk into a bathroom while wearing Tefilin, since the Parshiyos themselves are covered in leather.
However, the Gemara in Berachos (23a) teaches that Tefilin may not be brought into a bathroom unless they are placed in a covering that is not their designated covering. Even though the Parshiyos are already covered by their designated covering (the leather encasement of the Tefilin), they need an additional covering in order to be brought into a bathroom. The Gemara there seems to contradict the Gemara here, which says that if not for the "Shin" on the outside of the Tefilin, one would be permitted to walk into a bathroom with Tefilin without any additional covering, since the leather encasement around the Parshiyos suffices. How are we to reconcile these two Gemaros? (RASHBA to Berachos 23a)
(a) The RITVA here answers that the statement of the Gemara in Berachos -- that a holy object's designated covering does not permit one to bring it into a bathroom -- applies only when the holy object is sometimes removed from that covering. A Kamei'a and Tefilin, though, are never removed from their leather encasements. Even though the leather is made to hold the Kamei'a and Tefilin, one may walk into the bathroom with them (if not for the "Shin" on the outside of the Tefilin) since they are never removed from their encasements. When the Gemara in Berachos requires that the Tefilin be placed in a covering that is not designated for the Tefilin, such a covering is necessary because of the "Shin" on the outside of the Tefilin. Since the Tefilin are frequently removed from that covering, a designated covering does not suffice.
(b) According to RASHI in Berachos (23a), the Gemara there is not referring to one who brings Tefilin into a bathroom, but rather it is referring to one who places the Tefilin on the ground. The Gemara says that a covering that is designated for the Tefilin is not a sufficient separation between the Tefilin and the ground. Such a covering is a sufficient separation with regard to entering a bathroom with Tefilin. (MAGEN AVRAHAM OC 43:13; SEFAS EMES)
2) PLEASURE AND JOY
QUESTION: The Gemara says that the Rabanan did not prohibit Palyatan (balsam) oil after the Churban because it does not provide both Ta'anug (pleasure) and Simchah (joy); it provides only Ta'anug.
Based on this statement of the Gemara here, the BECHOR SHOR (at the end of Maseches Ta'anis, and cited here by Rav Yosef Engel in Gilyonei ha'Shas) explains an apparently self-contradictory Halachah in the laws of Tish'ah b'Av. The REMA (OC 553:2) explains that when Tish'ah b'Av occurs on Motza'i Shabbos, one may eat whatever he wants during the third Shabbos meal in the afternoon. However, one should not study Pirkei Avos, because after midday of the day before Tish'ah b'Av the practice is to refrain from learning Torah which rejoices a person's heart.
The TAZ (OC 554:1) asks that if one must have Simchah on Shabbos, and therefore one may eat whatever he wants throughout the entire day, then the same requirement of Simchah should permit one to learn Torah! After all, the only reason one is prohibited to learn Torah on Tish'ah b'Av (and Erev Tish'ah b'Av after midday) is because the words of Torah are "Mesamchei Lev" (OC 554:1).
ANSWER: The BECHOR SHOR answers that we see from the Gemara here that there is a clear differentiation between Ta'anug and Simchah. Ta'anug refers to the physical pleasure of eating, or of smearing oil on one's skin. Shabbos is called "Oneg" (Yeshayah 58:13). Therefore, on Shabbos there is a Mitzvah to partake of large and delicious meals, and one is permitted to do so even on Erev Tish'ah b'Av. However, Simchah is an entirely different Mitzvah; there is no Mitzvah of Simchah on Shabbos. Since learning Torah gives a person Simchah, one should not learn Torah after midday of Erev Tish'ah b'Av that occurs on Shabbos. (The ME'IRI in Beis ha'Bechirah, first Perek of Beitzah, also distinguishes between Oneg and Simchah and explains that there is no Mitzvah of Simchah on Shabbos, only on Yom Tov.)