Shabbat 12 - Work that is not needed
Earlier we saw that on Friday afternoon a tailor should not go into the street with his needle, because he may forget and continue carrying it after sundown, when Shabbat already started. However, in discussing the case of a zav (a man who had a gonorrheal discharge) , we find one ruling that allows him to carry a pouch to collect his discharge, while the other one forbids it. How are we to understand the opinion that it is allowed? The answer is that only that labor that is needed is prohibited on Shabbat. However, this man needs not his pouch but what collects in it (so that he can know when he becomes ritually pure), and that carrying is permitted - this is the opinion of Rabbi Shimon.
Another Friday night precaution: one should not delouse his garment or read a book, using a oil lamp, lest he strain to see something and adjust the light. On Shabbat during the day, how is one to delouse his garment? One should roll the flee between his fingers and throw it away, but not kill it. Nor should one do this in the street, out of respect for the passer-byes. Rabbi Ishmael ben Elisha thought that he could read by lamp light, and almost came to tilt the lamp. Some say, he did tilt it, and later wrote a note, "When the Temple is rebuilt, I will bring a fine sacrifice for my violation."
Can one visit sick people on Shabbat? Beit Shammai prohibit it, but Beit Hillel reluctantly allow it. One should pray for the sick when he visits, and say that "It is Shabbat, when we are forbidden to pray for daily needs, but the recovery is near."
Art: Carl Vilhelm Holsoe - Woman Reading by Lamplight