Siman 368

If the eruv was diminished from its measure that will be explained, if one Shabbat has not yet passed over it—they must add until its measure. But if one Shabbat has passed over it, even if only a fraction remains—it is kosher. For thus we learned in a Mishnah (80b): The remnants of an eruv—any amount. And anything over which one Shabbat has passed is called "remnants of an eruv," for it is not its beginning, since it already served on the first Shabbat; but if one Shabbat has not passed over it, it is called "the beginning of an eruv." And it appears to me that "any amount" is not literal, for it stands to reason that if less than a kezayit remains, it would not be considered an eruv, and certainly a kezayit is required. And from the Yerushalmi there, it appears to me that two-thirds must remain, as it says there: How much are they: "Remnants of an eruv, as Rabbi Yose said: hyssop with which one sprinkled one time—it is kosher, from here on it is its remnants, so too here," thus far its words. And the language is not settled, for is it so that one is not permitted to sprinkle with hyssop even several times when it is diminished? But we explicitly learned in the eleventh chapter of Parah: "The commandment of hyssop is three stalks, and its remnants are two," see there. Rather, this is the explanation: one time it requires being completely kosher, which is three stalks, and from here on it is called remnants. And so too here—its remnants means two-thirds. (So it appears in my humble opinion)

And in the name of the Maharil they wrote, that if the eruv broke, even before the first Shabbat – it is permitted, since at the time of placement it was whole, (Magen Avraham subsection 3) but this is not implied by the poskim. However, this is certainly so, that if it was only whole at the onset of Shabbat – we are no longer concerned if it breaks on Shabbat. And there is one who wrote the opposite, that even if it broke after the first Shabbat – it is good to make another, for that which the remnants of an eruv are valid, is specifically when there remains at least one whole loaf. (ibid. in the name of R.M.M.) And this too is explained in the poskim to the contrary, that even a slice is valid. (ibid. and Beit Yosef) And there is also one who says that this is specifically when there is also shitufi mevo'ot, for then the remnants of the eruvei chatzerot are valid even in any amount. But when there is no shitufi mevo'ot – the remnants of the eruv are of no use at all. (Magen Avraham ibid.) For this is implied by the language of the Mishnah there which says: that the remnants of an eruv may be any amount, because they only said to make an eruv in courtyards after they have joined in the alleyway so as not to cause the children to forget, and therefore they were lenient regarding the remnants of the eruv, but without this – no. But if so, it is a great wonder regarding the Tur and the Shulchan Aruch, who wrote this law plainly regarding eruvei chatzerot. And our teacher Yehonatan wrote this explicitly, that a courtyard that is without an alleyway – the law of the remnant of an eruv does not apply to it, see there. And in the Rambam I did not find this law of the remnants of an eruv at all, for the truth is that he rejected it from the halacha, as he wrote in the Commentary on the Mishnah, that the halacha is not so, and so wrote the Bartenura. (For he holds that the first Tanna disagrees with Rabbi Yose as the Tosafot Yom Tov wrote, and the Tur and the Shulchan Aruch hold that Rabbi Yose does not disagree with the first Tanna, and they hold that this "and they only said to make an eruv in courtyards etc." – is a matter unto itself, and they are not the words of Rabbi Yose, and so it appears in the Rambam chapter 5 halacha 13 see there. And this is certainly a wonder, that the Beit Yosef would not bring the opinion of the Rambam at all, and study this well).

And what is the measure of the eruv at its outset? When there are eighteen householders or fewer—a kigroget for each and every one is sufficient. And if they are more than eighteen, even if they are a thousand or more—its measure is food for two meals, which are eighteen grogerot, which are approximately six eggs; and some say they are approximately eight eggs. Thus wrote the Rambam, the Tur, and the Shulchan Aruch. And there is a great wonder in this, for a kezayit is half an egg, and we explicitly say in Shabbat (91a) that a grogeret is larger than a kezayit; so how could the calculation here be twelve zeitim which are eighteen grogerot? And the truth is that for this reason our teachers, the authors of the Tosafot (80b, s.v. 'agav'), wrote that the calculation of two meals is not according to the calculation of eggs, but rather large loaves, see there; but according to the Rambam, the Tur, and the Shulchan Aruch, it is a wondrous thing. And some have answered that here the six eggs are in their shells, while the zayit is half an egg without its shell, and the shell is significantly large in volume, and according to this it is possible that the grogeret is larger than a kezayit. (The Gra later in siman 486 and the Turei Zahav subsection 6). And one should add further to this, for behold we learned in the seventeenth chapter of Kelim that there are large, small, and medium eggs, and all the measures of the sages are in the medium, as we learned there; and regarding the two meals of an eruv—we shall say that they are large ones. And even though according to the Mishnah in "Keitzad Mishtatfin" (82b) it is difficult to explain thus, nevertheless one may be pressed to say this. And so too regarding grogerot we learned there in Kelim, that there are large, small, and medium ones. And it can be said that here it is with a small one, and that which says a grogeret is larger than a kezayit—that is with a large one; and from all these things together the difficulty can be answered, as is understood.

If they made an eruv and afterwards the eruv was damaged, and one of the residents of the courtyard came to return and repair it—and even though the remnants of an eruv are valid, yet here it was damaged before the first Shabbat (Taz, subsection 1), or when there is no mavoi here according to the opinion of those who disqualify the remnants of an eruv in a courtyard without a mavoi, as I wrote in section 2; and even without this, it can be said that they wish to repair it so that it does not become entirely ruined. If he comes to make the eruv from the original species, such as if they made the eruv with wheat bread and now too he repairs it with wheat bread and the like, even if he makes the eruv from their own—he does not need to inform them, for presumably it is pleasing to them. And there is one who says that he requires the knowledge of one of the members of the household (ibid., subsection 2), and this is according to the approach of the Tosafot and the Rosh in the previous siman. In my humble opinion, it appears that it is not necessary, for only at the beginning of an eruv is this required according to their approach, as I wrote there, but not when it had already been placed and was damaged, even if it was entirely consumed.

And if he comes to mix from another species, for example, if they originally mixed with wheat bread and now he wants to mix with barley bread, or vice versa, if it was completely finished and he wants to mix from theirs—he must inform them. And even according to the approach of the Rif and the Rambam there, that they may mix against his will—nevertheless, perhaps they do not desire another species but rather the previous species. But when he mixes from his own—he does not need to inform them, as presumably it is pleasing to them. And if the first was not finished but rather diminished, even though he mixes from theirs—he does not need to inform them, for since there still remains from the first species, they will not be concerned if the repair is from another species.

And all this is if he comes to add because it was spoiled. But if he comes to add because residents were added, and it did not contain two meals which suffice even for a thousand, then for them this is the beginning of an eruv. Therefore, if they have only one opening to this courtyard, and it turns out that they prohibit the residents of the courtyard—there is no need for their knowledge at all according to the Rif and the Rambam in the previous siman, even when he makes the eruv from theirs. And according to the Tosafot and the Rosh—he needs the knowledge of one of the members of the household. But when they have two openings, one to this courtyard and one to another courtyard—he must inform them, even when he makes the eruv from his own, for perhaps they do not desire to make an eruv with this courtyard but rather with the other. And even though when they make an eruv in both they will be permitted to carry in both, as will be explained in siman 378, nevertheless perhaps they are not pleased with a multitude of residents. And some say that when he makes the eruv from his own—there is no need to inform them. (The R"ri) And the reason is that he holds that it is permitted to carry in both courtyards, and if so, certainly they are pleased, and the reason that perhaps they are not pleased with many residents is a weak reason, and it is sufficient for when he makes the eruv from theirs and not from his own. (And in vain the Magen Avraham wondered about him in subsection 1, and so wrote the Tosefot Shabbat subsection 4) And also in the Mordechai this is explained, as he wrote: "New ones were added to them who had not yet made an eruv with them—he adds and grants them merit if he makes the eruv from his own, and he must inform them if he makes the eruv from theirs" Thus far his words; behold it is explicit that when he makes the eruv from his own there is no need to inform them.

If the bread of the eruv became moldy and unfit for eating, or if worms or many ants fell upon it—it is as if it has been completely consumed, and they must make a new eruv. Therefore, it is the custom to make the eruv a matzah cake, which does not mold quickly, and furthermore, they can keep it during the days of Pesach and can keep it all year. And they should see to keep it in a place where there is no moisture and under glass, for then ants will not fall upon it. And this is better than making an eruv every single Shabbat, lest they forget one Shabbat. However, if they wish to make an eruv every Shabbat eve and eat the eruv on Shabbat—the authority is in their hands, for the eruv only needs to exist at the onset of Shabbat, as I wrote in siman 394, see there. And there are those whose minds are more comfortable making it every Shabbat eve, because the eruv that is for the whole year is liable to become spoiled. (Taz, subsection 4, and see there that he wrote that it is also good to make an eruv every Shabbat eve without a blessing, see there. And it requires further study, for if so, it is an eruv in two places, and the residents are divided and prohibit one another, unless he makes the eruv on condition—if the eruv of the synagogue is invalid, my eruv is an eruv, and if it is valid, it is not an eruv; and it requires further study. And what he wrote not to rely on an eruv that has diminished and to make another—certainly it is so, and such is the simple custom.)