Question: If the people in each yard made an Eiruv amongst themselves with their houses, we can say that there is a yard open to the alleyway. The case would be where the people in one of the yards open to the alleyway nullified their entire domain, including any ownership in the yard and alleyway, to the people of one of the other yards open to the alleyway. This would enable those people to carry from the yard to the alleyway!

Answer #1: The Gemara did not ask this because there is an opinion in Eiruvin (66b) that one cannot nullify his domain from his yard to someone in another yard.

Answer #2: Additionally, without this the Gemara asks a good question.

Explanation: Rav is basing himself on his position on Eiruvin (68b) that one can nullify (to one person) and then nullify again (to an different person).

Explanation: We hold that even if the people in the yards made an Eiruv Chatzeiros amongst themselves it is permitted to carry (in the entire alleyway).

Explanation (cont.): This is because Rav who forbade carrying more than four cubits in the alleyway when the people in the yard made an Eiruv (but did not make a Shituf) is basing himself on the fact that he rules like Rebbi Shimon (see Eiruvin 74a) only when they did not make an Eiruv. However, Rebbi Yochanan rules like Rebbi Shimon whether the people in the yard made an Eiruv or not.

Opinion: We rule like Rebbi Yochanan.

Explanation: The Gemara later explains that this excludes Tzitzis and Mezuzah. This means that Rebbi Eliezer did not mean that all preparation for doing Mitzvos that apply on Shabbos push aside Shabbos, as the Shtei ha'Lechem etc.

Observation: This seems to imply that if we had not learned that Rebbi Eliezer requires a Gezeirah Shaveh, I would have derived to Tzitzis and Mezuzah from Milah that its preparations also push aside Shabbos.

Question: This is difficult. How would it have been possible to derive to Tzitzis and Mezuzah from Milah? It is understandable that the preparations for Milah push aside Shabbos, as the Torah tells us that Milah pushes aside Shabbos. However, doing the Mitzvos of Tzitzis and Mezuzah themselves do not even require pushing aside Shabbos! (Why would I think to derive that their preparations push aside Shabbos?)

Question: This is difficult. What is the question? Why don't we indeed derive that just as one harvests stalks for the Omer even if he found harvested stalks, so too he should harvest stalks for the Shtei ha'Lechem even if he found harvested stalks? Why don't we therefore learn two laws, that their preparation pushes aside Shabbos and that they should be harvested on Shabbos?

Answer #1: Rabeinu Tam answers that they are not similar enough that we should derive that the stalks for the Shtei ha'Lechem should be harvested on Shabbos. This is because the wheat and barley is generally cut already by Shevuos. The Gezeirah Shaveh only implies that the preparation pushes aside Shabbos.

Answer #2: Alternatively, it is possible to say that we cannot derive harvesting (stalks for the Shtei ha'Lechem should push aside Shabbos).

Answer #2 (cont.): How do we know that cutting the stalks for the Omer pushes aside Shabbos? This is derived from the Pasuk, "b'Charish uvi'Katzir Tishbos" as stated in Menachos (72a). Just as plowing is something one is permitted to do (but is not a Mitzvah to do), so too harvesting is merely permitted. This excludes the harvesting for the Omer which is a Mitzvah.

Answer #2 (cont.): The Torah reveals that this is only derived regarding the Omer, regarding which the Torah also says "harvest" and not regarding the Shtei ha'Lechem regarding which the Torah does not say "harvest." (In other words, not only does one have to have stalks for the Omer, but the harvesting itself is a Mitzvah.)

Answer #2 (cont.): It must certainly be that the only reason harvesting the Omer is permitted on Shabbos is because of the word "harvest" (indicating that the harvesting itself is a Mitzvah). If not, why would we say this law regarding the Omer more than regarding the Shtei ha'Lechem? Why wouldn't we say that the harvesting of the Shtei ha'Lechem is also a Mitzvah and therefore pushes aside Shabbos? (It must be we cannot derive the harvesting of the Shtei ha'Lechem from the Omer because the Torah implies that the only reason the harvesting of the Omer pushes aside Shabbos is because it is a special Mitzvah, which is not the case regarding the harvesting of stalks for the Shtei ha'Lechem.)

Question: This is difficult. Why does the Gemara need to give a reason for this? Why not suffice with the fact that we do not find it is included in things that push aside Shabbos? All other things that push aside Shabbos are derived from a Pasuk, and we do not learn one from another (that we can say these should be derived from one of them)!

Answer: However, it is possible to say that we should derive Tzitzis and Mezuzah from Sukah. What would you say in order to say Sukah is unique (and we cannot derive Mezuzah from it)? Sukah applies both in the day and at night. This is not a valid difference, as Mezuzah also applies in the day and at night! Tzitzis also applies by both according to the Rabbanan who argue on Rebbi Shimon in Menachos (43a), as they do not derive "And you will see it" as excluding pajamas but rather as excluding a blind person's clothing.

Observation: According to this answer that we would have derived from Sukah, one must say that one who passes the time for Tzitzis has nullified the Mitzvah. Otherwise, one could ask that we see this is true regarding Sukah (as opposed to Tzitzis), and therefore we should not derive Tzitzis from Sukah.

Observation (cont.): It is logical that one does not nullify Milah just because he has not yet done it, as the same Mitzvah of Milah he is obligated in on the eighth day he is obligated in on the ninth day. If he would have done the Bris on the eighth day he obviously would not do the Bris again on the ninth day.

Observation (cont.): However, one is obligated to perform the Mitzvos of Sukah, Tzitzis, and Mezuzah every day (that they apply). Even if he already did them today, he will still be obligated to do them tomorrow. Therefore, when the day passes and he did not do these Mitzvos on this day, he will never be able to fulfill the Mitzvos of that day on another day (as the next day is a new and separate obligation).

Question: How could we possibly derive from Sukah? The same question applies to all of the topics which the Gemara attempts to derive from later in the Gemara. On the contrary, we should derive from the Mitzvah of honoring parents and building the Beis Hamikdash that do not push aside Shabbos!

Answer: Our Gemara is deriving as follows. Just as we find that there are many Mitzvos that apply on Shabbos and whose preparation pushes aside Shabbos, we should also say that preparation for all Mitzvos that apply on Shabbos should push aside Shabbos!

Answer (cont.): Therefore, it is not possible to derive from the Mitzvah of honoring parents whose preparations are in fact the Mitzvah itself, and not deemed mere preparations for doing the Mitzvah. A son who fulfills the wishes of a parent who says, "slaughter or cook for me" is fulfilling the Mitzvah by honoring his parent when preparing the food. The building of the Beis Hamikdash is one Mitzvah that Hash-m commanded to build it (the building is the Mitzvah itself, not mere preparation).

Question: Why should we think that we should make up a Gezeirah Shaveh? A person cannot merely make up a Gezeirah Shaveh, and must have a tradition from his teacher that this Gezeirah Shaveh should be derived!

Answer: Perhaps there was a tradition that the words "Shivas Yamim" can be used for a Gezeirah Shaveh (even though no specific derivation was handed down, see Maharam).

Explanation: We do not know what to derive from Shivas Yamim.

Implied Question: This is despite the fact that we derive in Pesachim (5a) that just as Shivas refers to the seventh day of Yom Tov, so too Rishon means the first day. (Doesn't this show what is meant to be derived from this Pasuk?)

Answer: It is possible that this derivation in Pesachim (5a) is only from the word Shivas, not the word Yamim.

Implied Question: This is despite the fact that sheep, wine for libations, and oil for flour offerings are also brought with the Omer and Shtei ha'Lechem. (Aren't they the same as the four species since they also have four items total that need to be done to fulfill the Mitzvah properly?)

Answer: The four species of Sukos are different as the absence of any of them causes the Mitzvah not to be fulfilled, as stated in Menachos (27a). Later in Menachos (45b) we say that the lack of sheep does not hold back from fulfilling the Mitzvah of the Omer or Shtei ha'Lechem. Therefore, when the Gemara says it requires four species, it means that there is no Mitzvah of Lulav without all four species. However, with the others their Mitzvah can be fulfilled even if the accompanying items that are supposed to be brought are not brought.

Implied Question: The Gemara here does not delve further and try to derive from a Tzad ha'Shaveh from all of these suggested topics (Omer, Lulav, etc.) to derive that preparations for Matzah push aside Shabbos. (Why not?)

Answer #1: This is the way of the Gemara, sometimes it does delve further in this fashion and sometimes it does not. In any event, if it would have tried to derive from a Tzad ha'Shaveh there would have been a question on it anyway. Rabeinu Porat.

Answer #2: Alternatively, we find derivations directly from Pesukim even when these derivations could have been derived from a Tzad ha'Shaveh. This is similar to the rule that we find derivations from the Pasuk even when these derivations could have been derived using a Kal v'Chomer.

Implied Question: The Gemara often says, "Let the Torah write this law by this topic, and we could have derived the others from it." This means a Pasuk is not needed! (In other words, this implies the Gemara is asking that if could be derived from a method of learning, there would be no reason for the Torah to write it as a Pasuk!)

Answer: This is because if there was no Tzad ha'Shaveh and we could derive this Mitzvah from a different topic, the Torah would not have written a Pasuk since it would be so obvious. In this way it is not similar to the rule regarding a Kal v'Chomer which is more obvious type of derivation.

Explanation: This Pasuk is open for derivation in all ways. It is not needed to teach us a law regarding Lulav, as even though we derive "Yamim" - "days" and not nights, the Pasuk "Shivas" was not needed at all, as it could have just said "And you will be happy before Hash-m...in the days." Therefore the word "Shivas" is extra.

Question: How does Rebbi Eliezer derive "Yamim" and not nights? Since he holds of the Gezeirah Shaveh he should derive from Sukah that just as by Sukah "Yamim" includes nights, so too regarding Lulav it includes nights?

Answer: We cannot derive from a Gezeirah Shaveh something that the definition of the word used in the Gezeirah Shaveh itself seems to exclude. This is because "Yamim" implies days and not nights.

Implied Question: This implies that he means to say that Matzah does not apply by night as it does during the day, and this cannot be as on the contrary, the main Mitzvah of Matzah is on the first night as the Pasuk says, "In the evening you should eat Matzos. (What does the Gemara mean?)

Answer: It could have said (i.e. it must mean) that it applies both during the day and during the night (as opposed to Matzah that only applies mainly at night).

Explanation: Rebbi Eliezer therefore derive laws regarding each topic (Tekios of Rosh Hashanah and Yovel) from the other topic, as we derive in Rosh Hashanah that all the Tekios of Tishrei should be similar to each other, as explained by Rashi.

Explanation (cont.): The Rabbanan hold that it is not possible to compare them. Rather, the Pasuk teaches that the Tekios should be similar regarding the order of the Tekios. However, they are clearly not the same regarding the time that they are blown, as one is blown on Rosh Chodesh (i.e. Hashanah) and one on the tenth of the month.