ANSWERS TO REVIEW QUESTIONS
prepared by Rabbi Eliezer Chrysler
Kollel Iyun Hadaf, Jerusalem
Previous dafSukah 18
(a) If, in a *large* Sukah, one fills in part of a three Tefachim space in
the S'chach, with metal rods - the Sukah is Kasher (seeing as there is
neither the Shiur of space nor that of Pasul S'chach to invalidate it.
(b) If one did the same thing in a *small* Sukah - it would be Pasul,
because it does not have the Shiur S'chach of a Kasher Sukah.
(c) If one filled in part of the space with canes, the Sukah is Kasher,
because of the principle of 'Levud'. That is when it is *next to the wall*.
Rav Acha and Ravina argue what the Din will be in the *middle* of the Sukah.
According to one of them, the leniency in the former case only applies to
the *side* of the Sukah, but not to the *middle* - because, in his opinion,
'Levud only applies next to a wall, but not to the middle of the roof (or
(d) Ravina proves that 'Levud' applies even in the middle of the roof (or
the wall) from the Koreh of a Mavoy, where we validate two beams that
protrude from the two parallel walls at the entrance of a Mavoy, which stop
within three Tefachim of each other, because of 'Levud' - Rav Acha refutes
this proof, on the grounds that this is restricted to the beams of a Mavoy,
whose application is purely mi'de'Rabbanan.
(a) If a room has a Tefach by Tefach skylight, an object that is ...
Rebbi Yishmael b'Rebbi Yossi informed Rebbi Yehudah, who validated ...
1. ... directly underneath the skylight remains Tahor, if there is a piece
of corpse in the room.
(b) Ravina refutes the proof from here (that Levud does not apply in the
*middle* of a wall or ceiling) - because Hilchos Tum'ah have their own
2. ... in the room, remains Tahor, too, if the piece of corpse is directly
underneath the skylight.
(c) Clearly, it was handed down from Sinai that with regard to Tum'ah, there
is no Din Levud in the middle of a wall or ceiling - and one cannot learn
extend what is learned from Halachah le'Moshe mi'Sinai to any other area of
1. ... a Sukah with Pasul walls, provided there is at least seven by seven
Tefachim of Kasher S'chach in the middle - that, according to his father,
that applies only up to four Amos (where we say 'Dofen Akumah), but not
2. ... a type of small fish called Abruma - that, according to his father,
it depended on the river: the Abruma of certain rivers was permitted, but
of other rivers, it was forbidden.
(a) Similarly, Abaye permitted a type of small fish called Tzachnasa from
the River Bav. We initially thought that this was because the River Bav was
a swift-flowing river - and non-Kasher fish, which had no spinal cord, could
not survive in it.
Ravina concludes that, nowadays, fish from the River Bav are forbidden -
because the waters of other rivers, which bring insects with them, flow into
(b) That is not the case, however - because non-Kasher fish were known to
survive in similar swift-flowing rivers.
(c) Perhaps it was because the water was very salty, the Gemara then
suggested, and non-Kasher fish, which had no scales, could not survive in
(d) The reason that we ultimately permit Tzachnasa from the River Bav - is
not because we discovered them to be Kasher, but because the mud on its
river-bed simply did not produce insects, which would render even Kosher
(a) If S'chach is placed on top of a courtyard that is separated from the
adjoining passageway (which is more than four Amos wide) by means of posts
that are placed at intervals of less than three Tefachim apart - the
courtyard will serve as a Kasher Sukah, because, due to the Din of 'Levud',
the posts are considered a proper wall.
(b) Abaye validates it even if there are no posts - because, in his opinion,
we will apply the principle 'Pi Tikrah Yored ve'Sosem' to the inner vertical
section of the ceiling that surrounds the courtyard.
(c) Rava does not apply 'Pi Tikrah Yored ve'Sosem' in this case (we shall
see later why that is) See also Rabeinu Chananel.
(d) Abaye concedes that by a Sukah that has only two walls and S'chach
consisting of planks of less than four Tefachim wide, 'Pi Tikrah Yored
ve'Sosem' will not apply - due to the fact that, since it is open at both
ends, the Rabbanan forbade it because it resembles an open Mavoy.
(a) Rav permits carrying on Shabbos even more than four Amos inside an
Achsadra in a field that is not attached to a house - because he holds 'Pi
Tikrah Yored ve'Sosem' (even by all four walls). Shmuel concedes that the
principle of 'Pi Tikrah Yored ve'Sosem' by *three* walls, but not by *four*
(See Tosfos DH 'Achsadra').
(b) We initially suggest that, in the Machlokes between Abaye and Rava -
Abaye holds like Rav, and Rava, like Shmuel.
(c) We conclude however, that this is not the case. Even Abaye has to agree
that only Rav will agree with him, but not Shmuel. We cannot possibly
establish Shmuel by 'Achsasdra be'Bik'ah' exclusively, but by Sukah, he will
agree that 'Pi Tikrah Yored ve'Sosem' - because if he holds 'Ein Pi Tikrah
Yored ve'Sosem' by 'Achsasdra be'Bik'ah', where the walls *are* made for the
inside of the Achsadra, then he will certainly hold that, by our case of a
Sukah that is surrounded by an Achsadra, where they are *not*.
(d) Rava however, establishes that even Rav (who holds by Achsadra
be'Bik'ah, 'Pi Tikrah Yored ve'Sosem' - because the walls *are* made for
the inside of the Achsadra) will agree in the case of Sukah - where they are
*not* that 'Ein Pi Tikrah Yored ve'Sosem'.