ANSWERS TO REVIEW QUESTIONS
prepared by Rabbi Eliezer Chrysler
Kollel Iyun Hadaf, Jerusalem
Previous dafEruvin 43
ERUVIN 42, 43, 44 sponsored by a generous grant from an anonymous donor. Kollel Iyun Hadaf is indebted to him for his encouragement and support and prays that Hashem will repay him in kind.
(a) The proof from our Mishnah (that when the boat is moving, even Rebbi
Yehoshua and Rebbi Akiva permit one to walk the entire boat - like Rabah)
- is Lashon *'she'Ratzu* Lehachmir al Atzman', from which we can
infer that, strictly speaking, they were permitted to carry on the entire
boat - because it was moving (like the contention of Rabah), and that they
only declined to do so because they wished to be Machmir on themselves,
because maybe, the boat had stopped moving for a short while, in which
case, they would have been Koneh Shevisah, and would indeed be forbidden
to walk more than four Amos.
(b) The Gemara's second proof Mishnah, is juxtaposition
of the Machlokes of the boat, to the case of the man who was forcibly
removed by gentiles and placed in an enclosure etc.; just as *there*, the
enclosure is stationary, so too, does the dispute by the boat speak when
the boat is stationary.
(a) The Gemara was surprised at Rav Acha Brei de'Rava ruling like Raban
Gamliel in the case of the boat - since even Rebbi Yehoshua and Rebbi
Akiva only wanted to be strict with themselves, implying that, strictly
speaking, they agreed with Raban Gamliel. In that case, why would it be
necessary to rule like Raban Gamliel, since nobody argued with him?
(b) The questioner's mistake lay in failure to realize that Rebbi
Yeshoshua and Rebbi Akiva only agreed with Raban Gamliel by a boat that
was moving (as we explained a little earlier), but not when the boat was
stationary; and it was *there* that Rav Acha B'rei de'Rava found it
necessary to issue a ruling like Raban Gamliel.
(a) The Sha'aleh whether Techumin applies above ten Tefachim applies -
either to a long but narrow board which is higher than ten Tefachim, but
less than four Tefachim wide - (whether one may travel beyond the Techum
along that board); or whether someone who is able to fly, due to having
pronounced one of the Names of Hashem (even though doing so is forbidden)
- is permitted to do so beyond the limits of the Techum on that Shabbos or
(b) If there was no Techum on water above ten Tefachim - then why did
Rebbi Yehoshua and Rebbi Akiva want to be strict with themselves. There
were absolutely no grounds to be strict here, since, even if the boat did
stop (which was the cause of their Chumra), they would still be above ten
Tefachim and would therefore be permitted to walk in any case.
(c) There in fact, no proof re that Techumin above ten Tefachim
does apply - because the Mishnah could well be speaking when the boat in
question was traveling *below* ten Tefachim. But had it been higher, then
even Rebbi Yehoshua and Rebbi Akiva would have no reason to be strict with
(d) Nor is there is any proof from those seven Chidushim, which were said
one Shabbos morning in front of Rav Chisda in Sura, and again in the
afternoon in Pumbedisa in front of Rabah (which was well outside the
Techum Shabbos of Sura) - because who said it was Eliyahu ha'Navi who
whisked the Chidushim from Sura to Pumbedisa on that Shabbos, perhaps it
was Yosef the (learned) Demon?
(a) Why is the 'Nazir' (who has undertaken to be a Nazir on the day that
Mashi'ach comes), permitted to drink wine on Shabbos and Yom-Tov? Why do
we not not suspect that he may still come that very day, in which case the
Nezirus will become effective? Unless the Din of Techum applies even above
ten Tefachim, in which case we know for sure that Eliyahu cannot have
arrived on Friday.
(b) If the 'Nazir' was permitted to drink wine on Shabbos and Yom-Tov
because Eliyahu has not arrived by Friday, then he should be permitted to
drink wine *every* day, since, by the same token, Eliyahu had not been
known to arrive on the previous day, Mashi'ach would most certainly not
come on that day.
(c) Since Eliyahu had not arrived on the previous day, then why was the
Nazir not permitted to drink wine on the following day? is not a Kashya -
because it is possible that really, Eliyahu had indeed arrived, but his
presence remained as yet, unknown, because he went first to the Beis-Din
ha'Gadol to 'present his credentials' as it were.
(d) The reason that the 'Nazir' is permitted to drink wine on Shabbos and
Yom-Tov - is on account of the tradition that Mashi'ach will not come on
Shabbos or Yom-Tov, not for any intrinsic reason, but because Eliyahu
ha'Navi, who will always come one prior to the arrival of Mashi'ach, will
not come on Shabbos, in order to interfere with the preparations for
Shabbos, which have priority. In other words, people would take the
trouble to go and greet him, and that is wrong, because the preparations
for Shabbos take precedence.
(a) Eliyahu cannot come on Friday, in order not to interfere with the
preparations for Shabbos, as we explained above - but Mashi'ach *can*.
Why? Because the moment Mashi'ach arrives, all the nations will become
subservient to us, and we will not be short of servants to prepare Shabbos
We are forced to say that the 'Nazir' made his vow on a Shabbos or a Yom-
Tov - because, the Gemara concludes, that is the only day that he could
possibly be permitted to drink wine. On any subsequent Shabbos, there is
no way that he could drink wine, since he had already become forbidden
during the week (and how can the ban to drink wine be lifted?), so the
only day that drinking wine can possibly be permitted, is on the first day
when his vow was made on a Shabbos, because a. Eliyahu had not come on the
previous day - Friday, and b. he had not yet become forbidden to drink
wine on the previous day, as would be the case on all subsequent Shabbasos
(see Rabeinu Chananel - Rashi's explanation does not appear to follow the
text in our Gemara).
(b) There is no proof that there is Techumin above ten Tefachim, because
otherwise, why may the 'Nazir' not drink wine on Sunday, seeing as Eliyahu
cannot have arrived on Shabbos - because it may well be that the Tana who
was really not sure whether Techumin applies above ten Tefachim, forbade
the 'Nazir' to drink wine even on Sundays, because *maybe* there is *no*
Techumin above ten Tefachim, and Eliyahu ha'Navi will arrive on Shabbos
(although it is possible that there *is*, in which case, Eliyahu will not
come on Shabbos).
(a) Raban Gamliel in our Mishnah knew exactly where the Techum Shabbos
ended - by means of a tube whose length he adjusted so that, when he
peered down it, his line of vision, via the lower outer edge of the tube
would end at exactly two thousand Amos.
(b) In order to ascertain the height of a date-palm, one would measure
one's own height and the length of one's shadow - from which one would
know the ratio of his real height to that of his shadow; then he should
measure the shadow of the date-palm and apply the same ratio to the palm-
tree (twice the height or three times, or whatever it was).
(c) To measure the depth of a (very shallow) valley - one takes a tube
(whose maximum vision limit is for example, two thousand Amos, and moves
to the top of the ledge overlooking the valley. Then he moves back, still
looking through the tube, until he reaches a point where the valley is no
longer visible (due to the fact that it is outside the line of vision of
the tube, and not because of the angle of the valley). By detracting the
distance ledge to where he is now standing, he will know the
height of the valley.
(a) To prevent wild animals from resting in the shade of an earthen-
tombstone - he should first stick a post in the ground, in order to gauge
the direction of the shadow during the hottest time of day (since that is
also the direction that the shadow of the grave will stretch). Then, he
builds a sloping mound of earth leading off the tombstone in that
direction. In this way, the animal will be prevented from taking shelter
in the shade of the tombstone at that time of day.
(b) He would stick the post into the ground specifically after four hours
- when the sun begins to get hot (which is also the time when wild animals
usually come and look for shade)?
(c) We are afraid that the animal will not just rest beside the Matzevah,
but brush against it and knock it down.
(a) When Rav Nechemyah, Rav Nachman's disciple, engrossed in his studies
one Shabbos, walked straight outside of the Techum - Rav Nachman
instructed them to make a human Mechitzah to enable him to return.
(b) No! Rav Chisda had no problem with the Sha'aleh of whether a Mechitzah
that is made on Shabbos would be effective to permit Rav Nechemyah to
return to inside the Techum) - since Rav had already ruled like Raban
Gamliel, with regard to both gentiles who removed someone from his Techum
forcibly (to which our case - where Rav Nechemyah left his Techum be'Ones,
is comparable) and walking the entire ship which traveled beyomd the
Techum on Shabbos. What he wanted to know was whether the Halachah was
like Rebbi Eliezer, who permits someone who has walked two Amos outside
his Techum (and no more) to return to his Techum, under any circumstances.
In our case, the Sha'aleh therefore was whether - if there were enough
people to form a Mechitzah up to within two Amos of Rav Nechemyah's
original Techum, he would be permitted to return the final two Amos into
his Techum, even without an Eruv - like Rebbi Eliezer.
(c) We know that this is so from Rav Nachman, who replied 'Make him a
Mechitzah of people, *and let him enter*'. Now it is obvious that once
they made him a Mechitzah of people, he would be allowed to enter
(otherwise why would they have taken the trouble to make the Mechitzah)?
What he must therefore have meant is, that they should make Rav Nechemyah
a Mechitzah of people, and, in spite of the fact that the Mechitzah ended
two Amos short of his Techum, he was nevertheless permitted to enter -
like Rebbi Eliezer.