ANSWERS TO REVIEW QUESTIONS
prepared by Rabbi Eliezer Chrysler
Kollel Iyun Hadaf, Jerusalem
Previous dafEruvin 78
(a) A ledge of four square Tefachim protruding from a wall of *more* than
ten Tefachim is not sufficient to reduce the height of the wall.
(b) A ladder, even one that is *less* than four Tefachim wide, leaning
against the ledge (but not against the wall next to it) will be considered
(c) The two ledges that protrude from a twenty Tefachim wall must be
placed, one below ten Tefachim - with a ladder leaning against it, and the
other, above ten Tefachim. The ledges must be placed apart from each
other, in a way that allows for a ladder to be placed from one to the
(a) When Rav Huna says that a pillar ten Tefachim tall and four Tefachim
square that is stuck in the street, becomes reduced when one sticks a peg
in it - he is referring to the *width* of the pillar of four by four, the
minimum width for a Reshus ha'Yachid. By sticking a peg in it, one reduces
its width, so that it is no longer a Reshus ha'Yachid.
(b) Rav Ashi says 'Afilu she'Gavo'a Sheloshah' - because he holds that a
peg of three Tefachim can be used to hang things on, and consequently, it
is Chashuv and will not detract from the four Tefachim space (since one
can now use both the remaining space and the space taken up by the peg).
(c) When they asked Rav Ashi whether the same would apply if the top of
the board was full of pegs - he replied that one would also be Chayav,
since one could put things across the top (like one combines the earth
lying round a pit with the pit itself to make up four Tefachim width -
even though the only way they can be used together is by placing things
across the top).
(a) Rav Yehudah quoting Shmuel requires a ladder of fourteen Tefachim, to
reduce the height of a ten Tefachim wall - because if the angle of the
ladder would be more acute than that, it would be difficult to climb, in
which case, it would not be considered a Pesach.
(b) Rav Yosef permits even a ladder of thirteen and a bit - because
according to him, it will suffice, if the ladder reaches within the *top
Tefach* of the wall; whrereas Abaye permits even eleven and a bit, because
he holds that it only needs to reach within *three Tefachim*.
(c) Rav permits even a ladder of seven Tefachim and a bit, following the
leniency of Abaye, in addition to permitting a ladder even when it is
(d) Shmuel compared the ladder to the case of two platforms, one on top of
the other, which we permitted above (on the previous Amud).
(a) Both large sections of date-palm stumps and Babylonian ladders -
qualify as a Pesach even if they are not attached - because they are
1. The Amora who says this by Babylonian ladders, will certainly include
(c) If two ladders (neither of which is two Tefachim wide) are placed
near each other, and one adds straw in between the adjacent rungs of the
two ladders to join them together (thereby making up the four Tefachim) -
this will not constitute a Pesach, since the new straw rungs are too weak
to hold one's weight.
2. Whereas the one who says it by date-palm stumps will not include
Babylonian ladders - presumably, either because they are not as heavy as
the stumps, or because they are easier to transport.
(d) In the reverse case however, when one places a wooden ladder in
between a series of straw rungs, to make up four Tefachim - this will
constitute a Pesach, since it is possible to climb the rungs of the ladder
and to hold the straw section to help him climb.
(a) One would need to carve rungs in the wall ...
1. ... only up to a height of ten Tefachim high to widen the rungs of a
ladder that were not four Tefachim wide.
(b) This is because - in the former case, where he already has a ladder
going up to the top, it is sufficient to make up the deficiency in width, by carving rungs up to the height of four Tefachim to help him begin to
climb; once he reaches the height of ten Tefachim, it is easy to climb the
remaining distance to the top, even though it is less than four Tefachim
wide. Whereas in the latter case, where there is no ladder at all, and it
will be difficult to complete the ascent even after the initial ten
Tefachim, without anything to assist him, one requires rungs all the way
up to the top.
2. ... if there was no ladder - right up to the top of the wall.
1. A tree might not be considered a Pesach, even according to Rebbi, who
*validates* an Eruv on a tree - because that is only with regard to the
Din of Eruv, which becomes effective during Beis Hashemashos, when,
according to Rebbi, Rabbinical decrees (such as climbing trees) do not
apply on Shabbos; whereas a Pesach must be a Pesach for the whole of
Shabbos, which a tree is not.
(b) Rav Yosef's Sha'aleh by an Asheirah tree is - whether, even assuming
that other trees *are* called a Pesach, that is because there is *no* Isur
Hana'ah involved, whereas here there *is*.
2. On the other hand, it might be considered an Eruv, even according to
the Rabbanan, who *invalidate* an Eruv on a tree - because that is only
due to the fact that an Eruv has to be edible, albeit it only for the
duration of Bein Hashemashos; whereas as far as a Pesach is concerned, it
only needs to be called 'a Pesach' (which a tree *is* - during the week);
who said that it must be usable on Shabbos?
(c) Maybe an Asheirah tree (and our Sugya is confined to one that is
detached [see 7b] - Ritva) will not be called a Pesach, even according to
Rebbi Yehudah, who *permits* placing an Eruv on a grave - because there
(where Eruv Techumin is only permitted by a D'var Mitzvah, and where he is
not concerned that the Eruv be preserved, once it is Koneh with the entry
of Shabbos), he is deriving no benefit from it; whereas with regard to
using an Asheirah-tree for Eruvei Chatzeros (which is permitted even when
it is not for a D'var Mitzvah) - he *is*.
(d) Or it could be that, even according to the Rabbanan, who *forbid*
placing an Eruv on a grave - the Asheirah-tree will still be considered a
Pesach, since it really is a Pesach (with regard to gentiles), which has
'a lion riding on it' (i.e. an external reason - the Isur Shabbos, that is
preventing its use).
(a) Rabah replied 'Ilan Mutar, va'Asheirah Asurah'.
(b) Rav Chisda maintains - that the tree (which is Asur because the Isur
is one of Shabbos) should be Asur; and the (detached - see 6c) Asheirah,
which has nothing to do with the Isur of Shabbos) should be permitted.
(c) Rav Nachman bar Yitzchak, disregarding the previous Sugya - explains
that whether or not, a tree is considered a Pesach, is a Machlokes Rebbi
and the Rabbanan (Rebbi, who permits placing an Eruv Techumin on a tree,
will also consider a tree to be a Pesach; the Chachamim, who forbids it,
will not). And an Asheirah -tree is a Machlokes Rebbi Yehudah and the
Rabbanan (Rebbi Yehudah, who permits placing an Eruv on a grave, will also
consider an Asheirah to be a Pesach; the Rabbanan, who forbid it, will
not). Note: According to Rav Nachman bar Yitzchak, a Pesach follows the
same pattern as an Eruv, and must therefore be practically usable (at
least during Bein Hashemashos).
(a) For a dividing-ditch between two courtyards, to cause the two
courtyards to be obligated to make two separate Eruvin - it must be four
Tefachim wide, and it must run all the way across the Chatzer.
The Gemara differentiates between the straw *Mechitzah*, which is a
Mechitzah (since a Mechitzah is a Mechitzah whether one is Mevatel it
there or not), and the straw *in the ditch*, which constitutes a
Chatzitzah, (and a Chatzitzah is only effective if one is Mevatel it to
that place, not if it stands to be removed).
(b) If the ditch is filled with ...
1. ... straw or stubble - it will *not* be considered filled (since these
commodities are usable and stand to be removed.
(c) If one fills the ditch with earth - the two courtyards combine, so
that one may only make a combined Eruv; whereas when a plank is placed
across them, it has the Din of a Pesach, leaving them with the option of
either combining to make one Eruv, or of making two separate Eruvin.
2. ... earth or stones - it will, since earth and stones are normally
placed in a ditch to remain there.
(d) The Mishnah writes that the same Din of joining the two courtyards
with a plank, applies equally to two ledges that protrude from an upper
floor of two adjacent houses - giving them the same option of making one
combined Eruv or two separate ones, should they place a plank across from
one to the other.
'Bayis she'Mil'ehu Teven O Tzeroros, u'Bitlo, Batel' - is speaking about a
house (i.e. a room) which contains something which is Tamei Mes (and
therefore Metamei be'Ohel). As long as there is space in the house, the
Tum'ah fills the house, but goes only as far as the ceiling. By filling it
with straw and being Mevatel the straw there, one causes two things to
happen, one le'Kula, and one le'Chumra: 1. That the Tum'ah is now confined
to the space that is immediately above the Tum'ah (but not to the rest of
the house); 2. The Tum'ah now goes up beyond the ceiling, to the sky.