1) FORGETTING AND REMEMBERING IN THE MIDST OF A SIN
QUESTION: The Mishnah says that if a person forgets that it is Shabbos and throws or carries an object from Reshus ha'Yachid to Reshus ha'Rabim, and before the object lands he remembers that it is Shabbos, he is exempt. This is because he did not begin and end the Melachah while he was unaware that it was Shabbos. Rather, he only began the Melachah unaware that it was Shabbos. When the Melachah was completed, though, he was aware that it was Shabbos.
In the Gemara, Rava explains that the Mishnah is teaching two cases. First, if a person throws an object from Reshus ha'Yachid to Reshus ha'Rabim and he remembers in mid-flight that it is Shabbos, he is exempt. Second, if a person carries from Reshus ha'Yachid to Reshus ha'Rabim and remembers that it is Shabbos before he comes to a stop in Reshus ha'Rabim, he is exempt (this is the case that the Mishnah expresses with the words, "Zeh ha'Klal...").
RASHI (DH Ela Amar Rava) explains that according to Rava, the Mishnah teaches that one is exempt in a case in which he throws an object (when he remembers in mid-flight that it is Shabbos), and the Mishnah adds that one is also exempt in a case in which he carries an object. The Mishnah needs to add the case of carrying, because we would not have known that one is exempt in that case.
This is difficult to understand, because it seems that the opposite should be true. Once the Mishnah teaches that one is exempt from the obligation to bring a Korban Chatas when he throws an object and remembers in mid-flight that it is Shabbos, it is obvious that he is exempt when he carries the object and then remembers that it is Shabbos. Since he is able to stop the action and avoid the Melachah when he remembers that it is Shabbos, but nevertheless he continues and does the Melachah anyway, his act is considered intentional and he is certainly exempt from a Korban Chatas, as the Gemara says. In contrast, when he throws an object into Reshus ha'Rabim, he is unable to retract his act, and thus we would have thought that even though he remembers that it is Shabbos, his act is still considered to have been done fully unknowingly, since he cannot retract it. Why, then, does the Mishnah need to add that one is exempt when he remembers in the middle of carrying, if the Mishnah already teaches that one is exempt when he remembers in the middle of throwing?
ANSWER: The MAHARSHA (to Tosfos DH Ela) asks this question and offers the following answer. If the Mishnah had not added, "Zeh ha'Klal," we might have thought that one who inadvertently throws an object on Shabbos and then, before the object lands, remembers that it is Shabbos is Chayav. When the Mishnah says that one is exempt when he throws the object and then remembers that it is Shabbos, we might have thought that it refers to a case in which the person remembered, after he threw the object, that it was Shabbos and the object was caught by a dog (that is, the Mishnah is teaching one case and not several different cases). The reason why he is exempt is because the dog caught the object and it never came to rest where the thrower intended.
The second case in the Mishnah, in which one threw an object with intention to inflict a wound, refers to an object that was attached to one end of a rope, while the thrower is still holding the other end. Since he is able to pull back the object in mid-flight and prevent himself from doing the act of Melachah, if he remembers that it is Shabbos he is exempt.
However, we still would not have known that one who throws an object on Shabbos which he cannot retract is exempt if he remembers that it is Shabbos before the object lands. We would have assumed that it is like any other act of Shogeg, and he is Chayav to bring a Chatas. Accordingly, once the end of the Mishnah ("Zeh ha'Klal") reiterates that one is exempt when he remembers that it is Shabbos while he carries an object, we are forced to re-examine our interpretation of the Mishnah. Why does the Mishnah need to repeat this law? It must be that the beginning of the Mishnah indeed discusses a case in which one threw an object and remembered the prohibition while it was in mid-flight, and it teaches that he is exempt even when the object is not caught by a dog. (That is, the first part of the Mishnah discusses two distinct cases, and not one case.) The Mishnah's additional teaching of "Zeh ka'Klal" refers to a case of carrying, which was not discussed separately in the Mishnah.
In summary, had the Mishnah not taught "Zeh ha'Klal," we might have thought that one who throws is Chayav, and that the Mishnah does not discuss such a case. The "Zeh ha'Klal" teaches that one who throws is exempt. The first case of the Mishnah refers to an ordinary case of throwing and remembering, while the "Zeh ha'Klal" refers to walking with an object and remembering the prohibition while walking.
2) A MELACHAH THAT ENDURES
OPINIONS: The Mishnah states that "one is Chayav for performing a Melachah that endures on Shabbos." What does this mean?
(a) RASHI explains that the Mishnah means that "one is Chayav for performing a Melachah on Shabbos that endures." That is, "Shabbos" refers to when the Melachah is performed, and one is Chayav only if the Melachah endures for a long time.
(b) The RITVA explains that the Mishnah means that "one is Chayav for performing a Melachah that endures on Shabbos." That is, "Shabbos" refers to how long the Melachah must endure for one to be Chayav. As long as it endures for the duration of that Shabbos, one is Chayav. The SHA'AR HA'TZIYON (OC 303:68 and BI'UR HALACHAH) infers that the RAMBAM (Hilchos Shabbos 9:13) also understands that the Mishnah means that one is Chayav for a Melachah that endures for that Shabbos.
3) THE FINAL HAMMER BLOW
QUESTION: Among the Melachos that the Mishnah here lists is the Melachah of "Makeh b'Patish." RASHI explains that Makeh b'Patish refers to the final blow that a person gives to a rock which he chisels it out of a mountain, in order to break it off of the mountain. Rashi earlier (73a), however, explains that Makeh b'Patish refers to when the artisan strikes the hammer against the anvil after he flattens a metal strip, in order to smooth the surface of the metal strip. Why does Rashi give two different explanations for the act of Makeh b'Patish?
ANSWER: In the Mishnah earlier (73a), Rashi describes the Melachos as they were performed in the Mishkan. Therefore, Rashi explains there that "Makeh b'Patish" means the strike of the artisan's hammer on the anvil when his work is completed. There were no rocks that were chiseled for the construction of the Mishkan.
Here, though, Rashi does not give the same explanation for "Makeh b'Patish," because that explanation is the same as the act that Raban Shimon ben Gamliel adds at the end of the Mishnah. The Makeh b'Patish of the beginning of the Mishnah must be a different form of Makeh b'Patish (which the Mishnah mentions in order to teach the present-day applications of the Melachah).