OPINIONS: The Beraisa says that Chafei Posachas (teeth of a lock which are made of bone) are Tahor until they are placed into a lock. Why are they Tahor until they are placed into a lock? If they are considered a Kli, then they should be able to become Tamei even before they are not placed into a lock. If they are not considered a Kli, then they should remain Tahor even when they are placed into a lock.
(a) RASHI says that a Chaf is Tahor before it is placed into a lock because it is not usable at all by itself. Once it is placed in the lock, it becomes useful and therefore can become Tamei. Rashi explains that it becomes Tamei because Peshutei Kli Etzem (utensils made of bone which do not have receptacles) are like Peshutei Kli Matchos (metal) and are Mekabel Tum'ah. Even though it is attached to the lock, and a Kli that is attached to an object that is Tahor is itself Tahor, the lock itself has a receptacle (for the key) and is Mekabel Tum'ah. (This itself is a reason for why the Chaf can be Mekabel Tum'ah, since anything that is attached to an object that is Mekabel Tum'ah is also Mekabel Tum'ah; see 48b.)
(b) TOSFOS (DH Chafei) disagrees and says that Peshutei Kli Etzem are Tahor, as the Mishnah states in Kelim (2:1). Furthermore, the Chaf is the main part of the lock, and therefore it does not become Tamei as a result of being attached to the lock, which is Mekabel Tum'ah. On the contrary, the lock itself should not become Tamei because it is attached to the Chaf and is subordinate to it.
Tosfos also questions the first statement of Rashi. Rashi says that since the Chaf is not usable when it is not attached, it is Tahor. This, however, is obvious, and the Beraisa is teaching nothing new!
Rather, Tosfos explains that the Chaf alone does not become Tamei because it is a metal Chaf which has not yet been completed ("Golmei Kli Matchos"). Even though it is still fit for some uses even when it is not connected to the lock, it is Tahor because it is an unfinished metal utensil. Once it is attached to the lock, though, it becomes finished, and even though it has no receptacle, it is Mekabel Tum'ah because it is a finished metal utensil.
QUESTION: The Gemara discusses the amounts and types of rocks that one may bring with him into the bathroom on Shabbos. Why does the Gemara interrupt this discussion to ask whether one is permitted to move a spice mortar on Shabbos?
(a) RASHI explains that because of its shape, a spice mortar is fit for use for Kinu'ach (cleaning oneself) in the bathroom.
(b) TOSFOS (DH v'Im and v'Amar), says that the Gemara's mention of a spice mortar is unrelated to the topic of Kinu'ach. Rather, the Gemara is giving the maximum amount of stones that one may take with him into the bathroom. When one enters a temporary bathroom ("Beis ha'Kisei she'Eino Kavu'a"), one may take the amount of rocks equal in size to the "leg of a Meduchah Ketanah."


OPINIONS: Rav Chisda and Rabah bar Rav Huna said "something" in order to undo the witchcraft of the woman who cast a spell on their ship. What was it that they said?
RASHI in Chulin (105b, DH Amrei) offers two explanations. The first explanation is that they countered her spell by using their knowledge of black magic. The second explanation is that they uttered the Holy Name. Rashi here, too, understands that they uttered the Holy Name.
With regard to the second explanation, Rashi comments, "it cannot be proven" ("v'Lo Muchecha Milsa"; see Rosh Yosef). Rashi implies that the second suggestion needs strong backing in order to be considered valid. Why is that?
(a) In AVOS D'REBBI NASAN (12:13), we are taught that the expression, "d'Ishtamesh b'Taga Chalaf" (Avos 1:13), means that one who uses the Holy Name (for mundane purposes) will have no part in the World to Come. This interpretation is quoted by the REMA (YD 246:21). (Although we find in Sanhedrin (67b) that when Rebbi Yochanan and Reish Lakish learned Sefer Yetzirah, a calf was created, Rashi there explains that the calf came about by itself and they did not intentionally create it.)
(b) Rashi here, however, explains that the Amora'im used a "Shem Taharah" (Holy Name) to move the boat. This conforms to the opinion of the REMA (in YD 179:15), who permits the use of the Holy Name to perform miracles. In fact, "one who performs miracles with Hash-m's Holy Name demonstrates the greatness and mightiness of the Creator (LEVUSH, ibid.)." According to the Rema, the statement of Avos d'Rebbi Nasan apparently pertains only to those who are not on the proper level of holiness when they use the Holy Name. (It is possible that the words "Shem Taharah" that Rashi here uses, as opposed to the words "Shem Kodesh," are a euphemism for Shem Tum'ah, and Rashi's opinion here is consistent with his words in Chulin.)
HALACHAH: The SHACH (YD 179:18) quotes the LEVUSH who states that since it is almost impossible for one to be on the proper level of Kedushah and Taharah in order to use the Holy Name, one should refrain from using it except under dire circumstances.