QUESTION: The Beraisa (22b) states that when a Nasi dies, all of the learning in all of the study halls ceases in respect for the Nasi. The Beraisa continues (23a) and says that in the house of an Avel, words of "Shemu'ah" and "Agadah" (Halachic teachings and Agadic teachings) are not spoken. The Beraisa adds that Rebbi Chananyah ben Gamliel maintains that words of "Shemu'ah" and "Agadah" may be spoken.
Why does Rebbi Chananyah ben Gamliel permit the learning of "Shemu'ah" and "Agadah" in the house of an Avel? The Gemara (15a, 21a) states clearly that an Avel may not learn Torah during Aveilus.
Moreover, why does the Beraisa single out these two areas of learning, "Shemu'ah" and "Agadah," when it says that Torah may not be learned in the house of an Avel? The Beraisa earlier (21a) records a lengthy list of all of the areas of Torah learning which are prohibited for an Avel. Why does the Beraisa here not mention all of them, as the Beraisa earlier does?
(a) The RAMBAN (in TORAS HA'ADAM) explains that the Beraisa here refers to learning Torah in the house of an Avel on Shabbos. On Shabbos, an Avel is not permitted to observe any public practices of Aveilus. The Beraisa teaches that although an Avel may not observe Aveilus in public, he must refrain from learning these two parts of Torah. Rebbi Chananyah permits him to learn these parts of Torah on Shabbos because he maintains that refraining from learning them is considered a public act of Aveilus. Everyone agrees that if a practical Halachic question arises, the Avel is permitted to teach the Halachah.
(b) The RAMBAN gives a second answer. He says that the "Beis ha'Avel" mentioned in the Beraisa refers to the study halls mentioned earlier in the Beraisa, which must cease all learning activity at the death of the Nasi. The Beraisa now adds that not only is the regular Torah learning stopped as a sign of mourning for the Nasi, but the Talmidim may not even learn areas of Torah which do not require deep analysis and are not usually learned in the study halls. Rebbi Chananyah says that these areas of Torah may be learned in the study halls during the mourning for the Nasi.
(c) The SHULCHAN ARUCH (YD 378:7) cites the ruling of the Gemara as the Halachah. It is evident from the context of his words that he understands that the Gemara refers neither to Shabbos nor to the study halls of the Nasi, but to the home of an individual Avel. The SHEVET YEHUDAH explains that the Shulchan Aruch maintains that the Beraisa does not refer to what the Avel himself may or may not learn; the Avel himself certainly is prohibited from learning Torah. Rather, the Beraisa refers to others who come to visit the Avel. When they talk among each other, they may not talk words of Torah, even matters of "Shemu'ah" and "Agadah."
HALACHAH: The common practice today is to learn Mishnayos in the home of the Avel, in the merit of ("l'Iluy Nishmas") the departed relative. The Poskim write that this is a commendable practice. The NETZIV (Meshiv Davar 5:56) explains at length that since the Mishnayos are learned for the benefit of the soul of the departed, it certainly is permitted. The Avel himself, however, should not listen, because he is not permitted to learn. (If possible, the Avel should go into another room while the others who have come to comfort the mourner learn the Mishnayos together l'Iluy Nishmas the deceased.) In addition, the Talmidim of the deceased should not be the ones who learn Mishnayos, because the Gemara says that the Talmidim must refrain from learning.