Succah 19 - 25
The Leaves that Do Not Wither
"Even the casual remarks of Torah scholars should be studied." This counsel of the Sage Rav is based on King David's comparison of the Torah scholar to a "tree planted by a stream, which produces fruit in its season and whose leaves do not wither." (Tehillim 1:3) Even the least substantial part of this tree - the leaves, which symbolize the casual remarks of the Torah scholar - will not go to waste.
Two different dimensions of what can be learned from the conversation of the Torah scholar appear in Rashi's explanations here and elsewhere. In our gemara, the above counsel is cited in reference to a statement made by Rabbi Shimon regarding his experience in the succah of Rabbi Gamliel. Tevi, the non-Jewish slave of Rabbi Gamliel, slept under a bed in that succah. Rabbi Gamliel called this to the attention of his colleagues by exclaiming: "Did you see what sort of Torah scholar my slave Tevi is? He is aware that slaves are exempt from the mitzvah of succah and he therefore sleeps under the bed."
Rabbi Shimon's report on this incident concludes that "from the casual remark of Rabbi Gamliel we learned two things: 1) Slaves are not obligated in the mitzvah of succah; 2) One who sleeps under a bed has not fulfilled the mitzvah of sleeping in the succah (because the covered area created by the bed serves as a barrier between him and the succah)."
Rabbi Shimon intentionally used the term "casual conversation" rather than "words" in order to show that even though Rabbi Gamliel was not consciously teaching words of Torah to his audience, but was only priding himself on the wisdom of his slave, there was still so much to learn in halachic matters from this casual remark.
In Mesechta Avodah Zarah (19b) Rashi offers a different perspective of Rav's counsel. Even the casual remarks of Torah scholars should be studied in order to learn from them how to express oneself in their style of speech which is pure, rich and healing.
The two explanations are complementary rather than contradictory. When one listens carefully to even the casual remarks of a Torah scholar he is bound to learn something he did not know before, and how to express himself in better fashion.
The schach covering a sucah cannot be either too sparse or too thick. In regard to the minimum, the mishna tells us that there must be more space on top covered than left open, so that there will be more shade than sun. As regards the maximum, the same mishna seems to set no limit, for it states that "If it is thickly covered like a house, even if the stars are not visible inside, it is kosher."
In the Jerusalem Talmud, however, the inference is drawn from the mishna that a succah in which the stars are not visible is indeed kosher, but it is not the preferred way of making one. This is why the Shulchan Aruch (Orach Chaim 631:3) writes: "It is customary for the schach to be sparse enough for the stars to be seen through it, but if it was thick as a house and the stars are not visible it is still kosher."
Rabbeinu Tam, however, introduces another limitation. If the schach is so thick that rain cannot penetrate the succah it is not kosher. He offers two proofs. One is from a later mishna (28b) which states that a man may leave the succah if enough rain is falling to spoil his food. If one can make the schach thick enough to keep rain out, why should he not be required to make the schach rainproof rather than be exempt when rain enters?
A second proof is from the mishna in Mesechta Ta'anis (2a) which states that rain on Succos is a bad sign, because it prevents fulfillment of the mitzvah. If a succah can be made rainproof, the falling of rain should hardly be considered a bad sign.
Tosefos (Succah 2a) also mentioned a similar approach in explaining a statement by Rabbi Zeira. Rabbi Zeira who bases the disqualification of schach more than twenty cubits high on a passage (Yishayahu 4) describing the function of a succah, does not, however, require a succah to be rainproof based on that very same passage which mentions this as one of a succah's functions. His conclusion is that since a succah must be a temporary structure rather than a permanent one, it would be wrong for it to be rainproof.
Even though the Shulchan Aruch does not cite Rabbeinu Tam's opinion, the Mishna Berura (631:6) does cite later authorities who rule that if no rain can enter the succah, it is too much like a regular house and therefore not kosher. If, however, it is impossible to remove some of the schach to make it vulnerable to rain, one can rely on the more lenient opinions that it is still kosher.