By Rabbi Berach Steinfeld
Shulchan Aruch, Orach Chaim 318:1 discusses if a person cooks on Shabbos or does any other melachah intentionally, it is forbidden to the person who did the aveira forever and to others it is muttar after Shabbos. If the person did it beshogeg, it is forbidden on Shabbos; however, on Motzai Shabbos it is muttar for both him and others right away. If someone did Borer and took out one food from another food, it would stand to reason that the food is assur on Shabbos. What would happen if he remixed the food and it is as it was before? Would the food be permissible?
The Gemara in Shabbos 149a and Shulchan Aruch, Orach Chaim 360:13 say that a person is not allowed to look in a mirror on Shabbos because if the mirror is made out of metal you may come to rip off hanging flesh or hairs. The question is, why isn’t looking in a mirror not considered as if one is forming a picture? Forming a picture would be the tolda of koseiv; the halacha is that even if it is writing that does not last, it is forbidden. How could one look in a mirror on Shabbos?
To answer the first question, the Pri Megadim in 319:1 and Shailos U’tshuvos Rav Paalim 1:13 discuss this question. They both have a safek what the din would be. Do we say that since his action did not last since it got re-mixed, one may have hana’a from it? On the other hand, it could be considered a k’nas which does not get undone by making the object back to the same way it was before. The Rav Paalim compares it to somebody who tells a non-Jew to warm a pot. He may not have hana’a even after the pot cools off. We see that the k’nas stays even after the melacha wears off.
The Tzitz Eliezer 14:33 says we can’t compare it to a case of telling a goy, which is very stringent. We don’t want people being mezalzel in hilchos Shabbos. However, in the case of Borer, even if you will say it is assur on Shabbos, after Shabbos it will be muttar. He brings proof from the Ramban in Eiruvin 41b that says that maaseh Shabbos is assur. Nevertheless, if he took something into reshus horabim and brought it back in, he would be allowed to have hana’a since it was in his house to begin with. He therefore has no direct hana’a from maaseh Shabbos. In our case, where he remixes the food, he has no benefit from maaseh Shabbos so he may have hana’a. The Rashba disagrees with this position and says that if one moves something four amos in reshus horabim and then brings it back, it would be forbidden. The Tiferes Yisroel paskens like the Ramban and says that a person could benefit from this action.
Regarding the mirror, we can differentiate that in all cases of writing even if it does not last there is some sort of ink that is applied. There is some kesiva involved if he is engraving something in the dirt, even though it does not last. Conversely, someone who looks in the mirror is not applying any material to the mirror, and nothing is being engraved in the metal itself to make it considered ksiva. This would mean that a reflection is not a type of writing.
May we be zocheh to be mekayem Shabbos properly.
Regarding the Mirror question, He is right because I know someone that stayed in the dark the whole Shabos so as not to form a shadow. It also says “Lo Svarei Eish B’chol Moishvoiseichem” no light and no shadows.