ANSWERS TO REVIEW QUESTIONS
prepared by Rabbi Eliezer Chrysler
Kollel Iyun Hadaf, Jerusalem
Previous dafEruvin 5
(a) Abaye requires a trench - that extends four Amos into the Mavoy to
increase the height of the entrance.
(b) In the previous case, where the entrance has a wall (the edge of the
Koreh, about which we say [mi'd'Oraysa even above twenty Amos] 'Pi Tikrah
Yored ve'Sosem', as we discussed earlier), the trench is required, not to
create a wall, only to change the height of the Koreh; whereas, in our
current case, where the Koreh is less than ten Tefachim, we are now coming
to create a wall d'Oraysa by digging the trench, and the wall must have a
Hechsher Mavoy (four Tefachim, according to Rav Yosef, four Amos, according
(a) It is possible that Abaye holds like Rebbi Ami and Rebbi Asi (who rule
that a a wall of four *Tefachim* adjacent to the entrance permits a breach
of up to ten Amos next to it) - because *they* are speaking about a Mavoy
that was formerly Kasher (in which case, if four Tefachim remain, the Mavoy
remains Kasher); whereas *he* is speaking about the initial measurements of
a Mavoy (which is four Amos).
(b) If the remaining wall of at least four Tefachim is not there - then a
breach of three Tefachim will invalidate the Mavoy.
(c) This is because by a breach of three Tefachim we no longer
say 'Levud', combined with the suspicion that the people of the Mavoy will
now use the breach as an entrance (instead of the original one adjacent to
it); as a short-cut from the Mavoy to the street; and that is not
acceptable, since the breach has no Lechi or Koreh.
(a) A Lechi or a Koreh will only permit carrying in a Mavoy - if it has at
least two Chatzeros opening into it, and each Chatzer must have the front of
at least two houses leading into *it*.
(b) A Chatzer at the back of the house - was usually used as a wood-store
and was called a Rechavah.
(c) The Beraisa cannot be speaking when the Chatzer opened into the far end
of the Mavoy - because Rav Nachman has already taught us that the length of
a Mavoy must exceed its width; otherwise, it has the Din of a Chatzer (which
becomes rectifiable by means of a plank of four Tefachim or of two narrow
planks - but not by a Lechi or a Koreh, like a Mavoy). So since we are
speaking about a Mavoy whose length is four Amos, we must establish its
width at *less* than that, not more.
(d) Rav Yosef will establish the Beraisa- by a Mavoy of four Amos long, and
whose far end is less than four Amos. The Chatzeros are situated on the
corners, diagonally across the edge of the Mavoy.
(a) The reason that Rav Huna invalidates a Lechi of four Amos that extends
across the entrance of the Mavoy, is because a plank of four Amos is seen as
a Mavoy, and not as a Lechi. Is this not because four *Amos* constitutes the
length of a Mavoy - and not four *Tefachim*?
(b) Rav Yosef however, refutes this proof - on the grounds that a board of
four Tefachim may well be considered the wall of a Mavoy, yet that does not
mean that it will lose its status as a Lechi; *that* happens only when it is
four *Amos* long.
(a) When Rav Huna Brei de'Rav Yehoshua says 'de'Metafi Bei O de'Mevatzer Bei
- he meant that the added Lechi was not completely flush against the
existing one: it is either higher or lower than the Pasul one, or wider or
narrower than it.
(b) According to Rav Papa - the second Lechi is not placed beside the first
at all, but beside the opposite wall on the other side of the entrance.
(a) According to Rav Huna Brei de'Rav Yehoshua - a Mavoy that is less than
eight Amos wide becomes permitted if the plank stretches across the majority
of the entrance, because of 'Omed Merubah al ha'Parutz'.
Rav Huna brei de'Rav Yehoshua learns a leniency by Mavoy from Chatzer; he is
not concerned that a breach in a Chatzer only invalidates if it is at least
ten Amos, whereas a breach in the wall of a Mavoy invalidates when it is
four Amos or even four Tefachim - because, in his personal opinion, a breach
in a Mavoy also invalidates only if it is at least ten Amos - like that of a
(b) He learns this from a Kal va'Chomer from Chatzer - which does *not*
become permitted by means of a Lechi or a Koreh (yet it *does* become
permitted through 'Omed Merubah al ha'Parutz'), so a Mavoy, which does
become permitted through a Lechi or a Koreh, should certainly be permitted
through 'Omed Merubah al ha'Parutz'.
(c) We could learn a similar Kal va'Chomer from a plank of four Tefachim,
which permits a Chatzer - even if it is more than eight Amos, so how much
more so should we permit a Mavoy of eight Amos by means of a plank of four
(d) The problem with the Lechi of which we are speaking is that it was not
placed there in order to serve as a plank, which is why it is not valid as a
Lechi. For the same reason, it cannot serve as a plank (a Pas) either.
Rav Ashi declares the Mavoy Kasher even with an entrance that is eight Amos
1. ... when the standing plank is longer than the breach - because of 'Omed
Merubah al ha'Parutz'.
2. ... when the breach is longer than the standing wall - because then the
plank is considered a Lechi
3. ... when they are exactly the same size - because as we just learnt,
whether the Omed is more than the Parutz or vice-versa, the Mavoy is Kasher;
the only remaining possibility is that perhaps the Omed and the Parutz are
the same (in which case it will be forbidden to carry). Since this is a
Safek mi'de'Rabbanan (because min ha'Torah, carrying in a Mavoy is
permitted), we apply the principle 'Safek de'Divreihem Lehakel'. Nor is it
ever certain that they are exactly the same, because of the principle 'I