1) PREPARING A WOUND-COVER FOR USE ON SHABBOS
QUESTION: The Beraisa teaches that one may wear a wound-cover outside of his home on Shabbos, when he daubed it with oil before Shabbos, or when he wore it out of his home once before Shabbos. In such cases, the wound-cover is not considered an object that he carries, but rather a garment that he wears. The Beraisa implies that if he did not wear it on Friday, he may not go out with it on Shabbos because, as Rashi explains, it is not considered a garment.
If merely wearing the wound-cover once on Friday gives it the status of a garment, then the person should simple wear it on Shabbos inside his home in order to give it the status of a garment! Why does the Gemara not consider this option?
ANSWERS:
(a) According to RASHI, it could be that when one wears it on Shabbos without having daubed it with oil before Shabbos, one does not show that it is a garment. Since the wound-cover is normally worn with oil, if one wears it without oil on Shabbos he does not show that he likes to wear it that way and considers it a garment without oil. Rather, the reason why he is wearing it without oil is because it is forbidden to put oil on it on Shabbos! If he wears in on Friday without oil, it must be that he likes to wear it that way and considers it a garment even without oil (because otherwise he would put oil on it), and therefore he may go out with it on Shabbos.
(b) TOSFOS (DH Aval Lo) explains that the Gemara is not discussing whether or not the wound-cover is a garment with regard to walking out with it. Rather, the Gemara is discussing whether it is Muktzah -- whether it is considered designated for use on Shabbos? When the Beraisa says "one may go out" or "one may not go out" with it, it means "one may handle it" or "one may not handle it." Accordingly, one may not put it on even at home on Shabbos.
(c) RABEINU CHANANEL and the RAMBAM explain that this wound-cover ("Pikurin") is actually a wig (made to cover rashes on the head, -Rambam). According to this explanation, it could be that if one wears it on Shabbos for the first time, there is a fear that he may become uncomfortable and take the wig off after he walks out into Reshus ha'Rabim. If, however, he daubed it with oil before Shabbos, or if he tried it on Friday and saw that it was comfortable, the Rabanan permit him to wear it on Shabbos without fear that he will feel uncomfortable and remove it. (M. KORNFELD)
2) HALACHAH: PREPARING AN OBJECT FOR USE ON SHABBOS
OPINIONS: The Gemara cites three opinions concerning how a person must prepare an object for use on Shabbos so that it is not Muktzah: (1) he must do a formal act of preparation with the object; (2) he merely needs to think about using the object on Shabbos (that is, to mentally designate it for use on Shabbos); (3) he merely needs to use it once before Shabbos (with no formal act of preparation or mental designation). What is the Halachah?
(a) TOSFOS cites RABEINU SHIMSHON who rules leniently (one merely needs to use it once before Shabbos), because that seems to be how Rav Ashi and Rav Asi conclude in the Gemara.
(b) The RAMBAM (Hilchos Shabbos 25:21) rules that one must think about it before Shabbos (the second opinion in the Gemara).
(c) Tosfos cites RABEINU TAM who rules like the Tana Kama, that one must do a formal act of preparation. His ruling is based on a Gemara later in Shabbos.
HALACHAH: The SHULCHAN ARUCH (OC 308:20) rules like the lenient opinion of Tosfos (a), that using it once before Shabbos is sufficient preparation for Shabbos.

50b----------------------------------------50b

3) BRUISING AN OLIVE ON SHABBOS
OPINIONS: The Gemara discusses whether one may bruise an olive on Shabbos. Other than the problem of handling food disrespectfully, what law of Shabbos prohibits bruising an olive on Shabbos?
(a) RASHI explains that one bruises an olive to make it sweeter. TOSFOS (DH Mahu) explains that Rashi means that bruising an olive might be prohibited on Shabbos because one thereby makes it into an edible food item, an act which is prohibited on Shabbos (155a). The Rishonim dispute Rashi's explanation because according to Rashi, the question of bruising an olive has nothing to do with the subject of the Gemara here.
(b) TOSFOS YESHANIM and the other Rishonim explain that the question is whether or not one may bruise olives in order to obtain their juice to smear on one's skin on Shabbos. This is relevant to the subject of the Gemara here, because the Gemara has been discussing the use of various materials for washing one's skin on Shabbos.

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