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prepared by Rabbi Eliezer Chrysler
Kollel Iyun Hadaf, Jerusalem

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Eruvin 78


(a) Is a ledge of four square Tefachim protruding from a wall of more than ten Tefachim sufficient to reduce the height of the wall?

(b) Under what circumstances would a ladder leaning against it render it fit to do so? Would the ladder need to be four Tefachim wide?

(c) A wall of twenty Tefachim requires two ledges (and two ladders).
How exactly, would they need to be arranged to qualify as a Pesach?

(a) What does Rav Huna mean when he says that a pillar ten Tefachim high and four Tefachim square that stands in the street becomes reduced, when one sticks a peg in it?

(b) Some restrict Rav Huna's Din to a peg that is at least three Tefachim tall, others say even if it is less. Rav Ashi disagrees with Rav Huna. He says 'Afilu she'Gavo'a Sheloshah'.

(c) They asked Rav Ashi whether the same would apply if the top of the board was full of pegs.
What was his reply?

(a) Rav Yehudah quoting Shmuel requires a ladder of fourteen Tefachim to reduce the height of a ten Tefachim wall.
Why is that?

(b) Rav Yosef permits even a ladder of thirteen and a bit, and Abaye, even eleven and a bit.

(c) The biggest Chidush of all is that of Rav Huna Brei de'Rav Yehoshua. In fact, he holds like Rav.
What did Rav say?

(d) Rav himself, was surprised at this ruling, which he had received as a tradition.
How did Shmuel explain it?

(a) What do large sections of date-palm stumps and Babylonian ladders have in common?

(b) Which one of the two would we ...

  1. ... know from the other?
  2. ... not know from the other, and why not?
(c) If two ladders (neither of which was two Tefachim wide) were placed near each other, and one added straw in between the adjacent rungs of the two ladders to join them together (thereby making up the four Tefachim), would this constitute a Pesach?

(d) How about the reverse case (when he placed a wooden ladder in between a series of straw rungs, to make up four Tefachim)?

Answers to questions



(a) Up to what height would one need to carve rungs in the wall ...
  1. ... to widen the rungs of a ladder that were not four Tefachim wide?
  2. ... if there was no ladder?
(b) Why the difference?
(a) Rav Yosef asked Rabah whether a tree that serves as a ladder to climb a wall can be considered a Pesach.
Why might it ...
  1. ... not be considered a Pesach - even according to Rebbi, who *validates* an Eruv on a tree?
  2. ... be considered an Eruv - even according to the Rabbanan, who *invalidate* it?
(b) Rav Yosef asked Rabah further that, if we assume other trees to be a Pesach, will the same apply to the tree of an Asheirah.
What is the Sha'aleh?

(c) Why might it not be a Pesach - even according to Rebbi Yehudah, who *permits* placing an Eruv on a grave?

(d) And why might it be considered a Pesach even according to the Rabbanan, who *forbid* it?

(a) How did Rabah reply to Rav Yosef's two Sha'alos?

(b) Rav Chisda maintains that the opposite is more logical.
What is his opinion?

(c) The final opinion quoted is that of Rav Nachman bar Yitzchak, who holds neither like Rabah nor like Rav Chisda.
What does he say, with regard to both a tree and an Asheirah?

(a) What are the dimensions of a dividing-ditch between two courtyards, for the courtyards to require two separate Eruvin?

(b) Will the ditch be considered filled in, if it is filled with ...

  1. ... straw or stubble?
  2. ... earth or stones?
(c) A four-Tefachim plank lying across the ditch will also combine the two courtyards. What is the Halachic difference between the plank and the earth or stones in the previous case?

(d) What does the Mishnah write regarding two ledges that protrude from an upper floor of two adjacent houses?

9) How do we reconcile our Mishnah, where straw in the ditch does not divide between the two courtyards, and the Mishnah on the following Amud, which considers a hay-stack to be a Mechitzah to divide between two courtyards?

10) What are the ramifications of the Mishnah in Ohalos 'Bayis she'Mil'ehu Teven O Tzeroros, u'Bitlo, Batel'?

Answers to questions
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