This section starts the analysis of a new mishnah.
A tree while still attached to the ground cannot be used for skhakh, the roofing of the sukkah. Skhakh must come from a natural source, but it must be detached from the ground. Therefore, if one puts his sukkah underneath a tree it is invalid, just as it would be invalid if one built a sukkah inside a house with the ceiling as his roof.
If a person builds one sukkah on top of another, it turns out that the skhakh of the bottom sukkah is the floor of the top sukkah. Even if the skhakh meets all other halakhic requirements it is still invalid because the fact that someone is living above makes it again similar to a person who builds his sukkah inside a house.
Rabbi Judah holds that if there is no one who is living in the upper one, than the bottom one is valid. The upper sukkah is not considered to be living quarters unless someone is actually living there.
The mishnah taught that a sukkah that is underneath a tree is invalid. Rava says that this is only so if the tree provides more shade than the sun shining through. But if it allows more sun to shine through, then the sukkah underneath is valid because the tree isn’t like kosher skhakh.
The Talmud says that Rava derives this halakhah from the precise wording of the mishnah. The mishnah says that a sukkah built under a tree is “as if he made it within a house.” The mishnah could have stated simply that such a sukkah is invalid. Usually the mishnah is as concise as possible. According to Rava the reason that the mishnah adds in that such a sukkah is as if it was built in a house is that it wishes to limit the invalidity of such a sukkah to a case that is just like a house. Just as a house would provide more shade than sun, so too in order for the tree to invalidate the sukkah underneath it needs to provide more shade than the sun it lets in.
In yesterday’s section Rava said that if the tree lets in more sun than the shade it provides, the skhakh underneath is valid. Today’s section questions this.
The Talmud raises the problem that even if the tree lets in more sun, still the tree’s leaves and branches are invalid as skhakh. Therefore, he is joining invalid skhakh to valid skhakh, which should invalidate the sukkah.
R. Papa answers that for the sukkah to be valid, he must weave the invalid live branches with the valid skhakh (cut off from the ground). This would serve to make it look as if it was all valid because one wouldn’t notice the difference between the valid and invalid branches. And as long as at least 50 per cent of the skhakh is indeed valid, the sukkah is indeed kosher.
The Talmud now raises a typical difficulty: this is obvious! If he wove the valid skhakh in with the invalid live branches, it is obviously valid. So why would we even need to teach this?
The Mishnah has to teach that if he interweaves the valid and invalid skhakh. If it had not explicitly taught that it is valid we might have thought that we would decree that such a sukkah is invalid lest he validate even a case where he didn’t interweave the valid and invalid skhakh. In other words, we might have thought that we would be stringent and not allow this type of sukkah (the interwoven) to be valid, so the mishnah taught that it is valid.
The Talmud now raises another difficulty—haven’t we already taught that if a person weaves together valid and invalid skhakh it is valid. The mishnah teaches that if one takes vegetation still attached to the ground and puts it on the sukkah, the sukkah is still valid as long as there is more valid (unattached) skhakh than invalid skhakh.
We then have to ask whether this mishnah describes a case where he wove them together or didn’t. If he didn’t weave them together, then we have the same problem we discussed above—he joins invalid skhakh with valid skhakh.
Therefore, the mishnah must refer to a case where he did interweave the valid and invalid skhakh. So if this mishnah teaches that we don’t decree that such a sukkah is invalid, why would we need our mishnah to teach the same thing.
There is a subtle difference between the two mishnayot. The mishnah about the vine teaches that ex post facto, if this situation arises, the sukkah is valid. Our mishnah teaches that ab initio one is allowed to intentionally build a sukkah in this way. Thus both mishnayot are necessary.
Our section continues to explain another section of the mishnah, where we learned that if one placed one sukkah above another, the bottom sukkah is invalid.
As stated in the introduction, a sukkah built underneath another sukkah is invalid. The Talmud cites a baraita which uses a verse to derive that the skhakh must be directly under the sky. It can’t be underneath another sukkah, underneath a tree or underneath the roof of a house.
The Torah literally says, “You shall dwell in sukkot”—using the plural form. It would seem therefore that one could indeed dwell in two sukkot, where one was built underneath another.
In Hebrew, the word “In sukkot” is written without the vav. While we pronounce the word as a plural, we could read it in the singular. This would give the impression that it is singular. One cannot dwell in a sukkah which is underneath another sukkah.
Rabbi Jeremiah will now begin an extended explanation of four different scenarios where one sukkah is on top of another. There are four possibilities as to their validity, and he will explain how each works out.
If the lower sukkah’s skhakh lets in more sun than shade, then this skhakh is not valid in any case. It does not count as a sukkah. So if the upper skhakh is valid and is within 20 cubits of the ground, then only that skhakh counts as the covering of the sukkah and the bottom sukkah is valid.