On 30b, the Gemara asks why keduasha is chal on the schach all 7 days, unlike an esrog. But what is the comparison. we just said that you can't make a tenai on the schach since you can't say aini bodeil kol bei hashmashos due to the issur of soseir. But who said that you can't make a tenai on an esrog? So why can't we just say that by esrog you can make a tenai. and therefore the kedusha only goes as per the tenai, but by schach. since the tenai is invalid, the kedusha sets in and goes the whole yom tov.
Yaron Barach, Brooklyn, NY
Yaron, it is good to hear from you again!
This is another very sharp question.
1. We may learn the Peshat in this Gemara from the words of the Ramban in Milchamos Hash-m (page 17a of the pages of the Rif). The Ramban writes that the question of the Gemara is: what is the difference between Esrog and Sukah? Why is it that one may make a Tenai on Esrog but one may not make a Tenai on Sukah? The Ramban adds (his words are terse but this is his intention) that one cannot say that the difference between Esrog and Sukah is that Esrog is only mid'Rabanan while Sukah is d'Oraisa, and therefore the Tenai works for a d'Rabanan but does not work for the more severe d'Oraisa level. The reason why one cannot say this is that there is a principle, "Kol d'Tikun Rabanan k'Ein d'Oraisa Tikun" -- when Chazal instituted Halachos they did so on the basis of the Torah model. Therefore, if a Tenai is effective for Esrog then it must also be effective for a Sukah. (This explanation of the Ramban's words is based on the Ran that I wil cite soon, b'Ezer Hash-m.)
2. So you were correct in your question that a Tenai does indeed work for the Esrog. Now the Gemara goes further and asks that since we know that a Tenai works for Esrog it should follow that it also works for the Sukah since there is no difference between d'Rabanan and d'Oraisa.
3. The Ran on the Rif (17a, DH u'Mai) explains further that since a simple Tenai suffices for Esrog, it should also suffice for Sukah. Therefore, even if one did not say, "Eini Bodel...," the Tenai on the Sukah should work. Just as there is an Isur of Soser on the Sechach, there is an Isur d'Rabanan on the Esrog because it is "Huktzah l'Mitzvaso" -- it has been set aside to be used only for the Mitzvah of Esrog. Since this did not prevent the Tenai from working on the Esrog, the Isur of Soser also should not prevent the Tenai from working on the Sukah. This is the Gemara's question: What is the difference between Esrog, where a Tenai does work, and Suka, where a Tenai does not work?
Kol Tuv,
Dovid Bloom
Reb Dovid,
Thanks as always for the reply and the kind words.
What I don't understand about the Ran is the Gemara's answer with the chiluk that esrog doesn't apply at night. What does that have to do with the question? The question was why a tenai doesn't work by sukkah as it does by esrog, so what difference does it make if the Mitzvah applies at night? And I don't follow what the Ran ends off with, that since esrog doesn't apply at night, they didn't make it like a yoma arichta. How does that affect if a tenai should work or not?
Kol tuv
Yaron
1. Since the Mitzvah of Esrog does not apply at night, this is a reason why the Tenai can work. A Tenai cannot help in the middle of a Mitzvah to remove the prohibition of benefiting from the item with which one performs the Mitzvah. However, when the Mitzvah has terminated, even if only temporarily, the Tenai can work to prevent the Isur from coming back onto the item. Therefore, when night arrives, the Esrog is no longer an object of Mitzvah and the Tenai takes effect, and one is allowed to eat the Esrog. In contrast, the Mitzvah of Sukah continues straight for seven days and nights, and does not cease for one moment of that period. Therefore, a Tenai cannot help to remove the prohibition against benefiting from the Sukah.
2. According to the above explanation, we now understand what the Ran means about the long day. As far as the Sukah is concerned, the entire seven days of Sukos are equivalent to one long day because the Mitzvah never stopped in the middle. In contrast, Esrog is considered like seven different Mitzvos because each day it starts afresh after a night when no Mitzvah of Esrog existed. With regard to Esrog, Sukos is not considered one long day. Since it is a Mitzvah with a break in the middle, the Tenai can work during that break. In contrast, there is no break from the Mitzvah of Sukah during Sukos, so the Tenai cannot take effect.
Kol Tuv,
Dovid Bloom