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prepared by Rabbi Eliezer Chrysler
Kollel Iyun Hadaf, Jerusalem

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Eruvin 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 to Abaye).

(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'.

(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 Tefachim?

(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.

7) 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 Chatzer.

8) Rav Ashi declares the Mavoy Kasher even with an entrance that is eight Amos wide ...

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 Efshar Letzamtzem'.
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