1) WHITE LICE
QUESTION: The Gemara relates a peculiar practice of the mother of Mar brei d'Ravina. She made seven sets of clothing for her son to wear, one for each day of the week. RABEINU CHANANEL explains that she did this so that he would not be bothered by Kinim, lice, which would distract him from learning.
Why did she have to make seven sets of clothing? If her aim was to rid his clothes of lice, then it would have sufficed simply to make him two sets of clothes and to wash one set every day!
ANSWER: The answer to this question may lie in the Gemara in Pesachim (112b). The Gemara there quotes Abaye who says that one of the causes of Tzara'as is wearing clothes that were used within eight days after being washed, because within eight days Kinim Levanim (white lice) may still appear in the clothes.
According to Abaye's teaching, it is clear why Mar brei d'Ravina needed seven separate sets of clothing. It would not help to wash his clothes one day and to wear them the next, because the Kinim Levanim would infest them. Mar brei d'Ravina needed a separate set of clothing for each of seven days, so that when each one was washed, it would not be worn until eight days had passed! (Y. Tavin)
2) HALACHAH: RENTING THE DOMAIN OF A NOCHRI IN ORDER TO MAKE AN ERUV
QUESTION: Reish Lakish and the students of Rebbi Chanina arrived at a certain inn where they planned to stay over Shabbos. They wanted to make an Eruv Chatzeros to permit themselves to carry from their rooms into the Chatzer of the inn. One of the rooms, however, was rented by a Nochri who was out of town. Reish Lakish ruled that they could rent his room from the innkeeper, since it was in the innkeeper's power to evict the tenant. Rebbi Afas later concurred with Reish Lakish's ruling, and the Halachah follows Reish Lakish in practice.
Many Jewish communities today have an "Eruv." What we call an "Eruv" today is not the precise "Eruv" of the Gemara. Rather, what we call "Eruv" is the ritual enclosure utilizes Halachos such as Tzuras ha'Pesach to form a Mechitzah around the city (or neighborhood). This virtual wall around the city gives the city the status of one large Chatzer. However, even though the Mechitzah gives the city the status of a Chatzer, an "Eruv Chatzeros" must be made in order to permit carrying there. The Eruv Chatzeros is usually made by the rabbi of the city, who is Mezakeh some food (a loaf of bread or box of Matzah, for example) to all of the Jews in the city and places it in one of the houses in the Chatzer (the city).
However, the presence of non-Jews who own property in the city prevents the Eruv from being effective. The Gemara teaches that in order to make the Eruv effective, the rabbi must go to every non-Jew and rent from him the right to carry on his property (on Shabbos). This is practically impossible today, because there are usually thousands or hundreds of thousands of non-Jews in the city, and even if it were possible to approach every non-Jew, some might not consent to the rental agreement. In addition, public thoroughfares (such as streets) also need to be unified under the collectively-owned consortium of the Eruv. From whom does one rent the right to carry in those public areas?
ANSWER: The Gemara here teaches a solution to this dilemma. We learn from the ruling of Reish Lakish that whoever is in charge of an area and has the power to evict people from that area has the right to lease it as well. Where a public area such as a street is concerned, the rabbi may rent it from someone (or from that person's Shali'ach) who has the authority to evict residents from that area. Such a person might be the chief of police (and, by extension, any police officer who is an agent of the police chief) or the mayor. Similarly, if the police chief or the mayor has the right of entry to each person's home, then one may rent access to all of the non-Jewish homes in the city from him. (See SHULCHAN ARUCH OC 391:1; see also "The Contemporary Eruv -- Eruvin in Modern Metropolitan Areas," by Rabbi Yosef Gavriel Bechhofer (Feldheim Publishers, 1998), ch. 5, for a summary of the issues involved with renting rights from non-Jews for the sake of making an Eruv Chatzeros.)
3) WHEN A NOCHRI ARRIVES ON SHABBOS
QUESTION: The Gemara discusses a case of a Chatzer in which Jews resided with one Nochri. The Nochri was not present in the Chatzer at the onset of Shabbos, but he arrived during Shabbos. The Gemara discusses whether the Jews may rent the Nochri's property from him and, with Bitul Reshus, thereby permit carrying in that Chatzer on Shabbos.
RASHI's words here are difficult to understand. Rashi (DH d'Asa, according to the text as it appears in our edition) first writes that the Jews could have made an Eruv when the Nochri was not home on Erev Shabbos. According to Rashi's words, the Gemara's question presumably applies to a case in which the Nochri returned to the Chatzer after they made an Eruv (see Tosfos). The Gemara discusses whether the Nochri's presence annuls their Eruv and requires them to rent his property from him.
Rashi then writes that they did not make an Eruv before Shabbos. Rashi implies that had they made an Eruv, it would not have been effective, because they were required to rent the property of the Nochri (even though he was not present) and they did not do so. When the Nochri arrived on Shabbos, the Jews sought to rent his property from him and be Mevatel their Reshus to each other in order to permit themselves to carry in the Chatzer. This contradicts Rashi's original statement that they could make an effective Eruv when the Nochri is not present.
ANSWER: The Rishonim record two completely different explanations in the name of Rashi (see Tosfos DH d'Asa). Upon close examination it seems that Rashi revised his original explanation and wrote a new one, and both versions were recorded in our text of Rashi. (It is also helpful to accept the emendation of the HAGAHOS DIKDUKEI SOFRIM, who suggests that the words, "v'Lo Irvu me'Esmol, v'Lo...," should read, "v'Ilu Irvu me'Esmol, Lo....")
The words in Rashi's first version read, "v'Ilu Irvu me'Esmol, Lo Havu Matzi Metaltelei b'Chatzer." Rashi is saying that even if they would have made an Eruv on Erev Shabbos, they would not have been able to carry in the Chatzer on Shabbos before the arrival of the Nochri. This follows the opinion of Rebbi Meir (86a), which is not accepted as the Halachah by most Rishonim (see Tosfos DH Ikle'u, and the Gemara on 47a).
The words in Rashi's second version, which were added to the beginning of Rashi's comment, begin from the words (in our text of Rashi), "d'me'Esmol Shapir..." until the words, "Heicha d'Leisei." Rashi is saying that had they made an Eruv on Erev Shabbos, they would have been able to carry in the Chatzer on Shabbos before the arrival of the Nochri. This follows the opinion of Rebbi Yehudah and Rebbi Shimon (86a), which Rashi himself accepts as the Halachah (see Rashi DH Ikle'u, and Tosfos DH Ikle'u).
Rashi's first version seems to address a fundamental question that the Rishonim ask on the Sugya. We know that if all of the residents in a Chatzer participated in the Eruv except for one person who forgot to join the Eruv, in order to permit carrying in the Chatzer that person needs to be Mevatel his Reshus to all of the other residents. This is because all of the other residents already have an Eruv, and they lack only that person's Reshus in the Chatzer. As soon as they get that person's Reshus, the Eruv unites the residents in the joint ownership of the Chatzer, and it permits them to carry there. Even though it did not work before the person was Mevatel his Reshus, now that he was Mevatel his Reshus the Eruv is "Chozer v'Ne'ur" -- it becomes re-activated.
In the Gemara's case, however, Bitul Reshus does not seem to be necessary, because there was already a full-fledged Eruv. The Halachah follows the opinion of Rebbi Yehudah and Rebbi Shimon who maintain that the Jews may carry in the Chatzer with an Eruv when the Nochri is not home. In the case of the Gemara here, the Jews presumably made an Eruv on Erev Shabbos when the Nochri was not home and was not expected to return on Shabbos. When they made the Eruv, it was a valid, effective Eruv. Later, during Shabbos, the Nochri returned and the Eruv became invalidated. When the Jews rent his domain from him, the Eruv becomes re-activated and they should once again be permitted to carry in the Chatzer because of the Eruv. No further measure (such as Bitul Reshus) should be necessary. However, from the Gemara later (66b) it is clear that in this case, to rent the domain of the Nochri does not suffice -- it is also necessary for all of the Jews in the Chatzer to be Mevatel their Reshus to one of the residents in order to carry there. Why does the original Eruv -- which was effective until the Nochri came -- not become effective again when his Reshus is rented from him and no longer stands in the way of the Eruv?
Rashi's first version answers this question. Rashi explains that the Gemara here follows the opinion that when the Nochri is not home on Shabbos, the Jews may not carry in the Chatzer unless they rented his Reshus from him. Therefore, on Erev Shabbos the residents of the Chatzer did not make an Eruv, because it would not have helped. Later, on Shabbos, when the Nochri shows up and the Jews rent his Reshus from him, the question arises whether they may be Mevatel Reshus in order to permit carrying in the Chatzer.
TOSFOS (DH d'Asa) suggests a different approach, which can be used to answer Rashi's second version. If the Jews made an Eruv on Erev Shabbos and they did not rent the rights to the property of the Nochri, when they finally do rent his property from him the original Eruv does not become effective. This is in contrast to a situation where one of the Jewish residents of a Chatzer forgets to join the Eruv. The reason for this distinction is that if a Jewish resident forgets to join the Eruv, he nevertheless is fit to join the Eruv even though he has not chosen to join the Eruv. (In addition, as the Ritva points out, we assume that he will probably cooperate and be Mevatel his Reshus.) Therefore, the Eruv can be tentative until he is Mevatel his Reshus. When, however, a Nochri lives in the Chatzer, the Eruv that was made originally is void, because the Nochri is not fit to join the Eruv, and we also have no reason to assume that he will agree to lease his Reshus to a Jew. The Eruv cannot become "re-activated" when the Nochri eventually does lease his Reshus to the Jews.