Explanation #1: Rashi explains that they ruled that the farmer was impure for a night because he touched vessels that hovered over a dead person, and those vessels were impure for seven nights. This is according to the law that a person who touches a Tamei Mes is impure for one night according to Torah law.

Question #1: This is difficult. Why did the listener make a mistake and think that it was impure for seven days, since it is a simple law that a person who touches something Tamei Mes is only impure overnight?

Question #2: Additionally, according to Torah law the farmer is impure for seven days because he connected to impurity, as something that "was close" to something that "was close" to a dead person is impure for seven days according to Torah law, as stated in Avodah Zarah (37b). Even if this is through impurity of an Ohel there is still a law that he is impure for seven days, as stated in Ohalos (1:3).

Explanation #2: It therefore appears that they said the farmer was impure for seven days due to his connection with something that became impure. The person who heard this made a mistake because it is not obvious that one who connects to something that became impure should be impure for seven days.

Explanation #2 (cont.): This person thought that he was impure due to Ohel, since there is a circumference of a Tefach around this object. This is why the Mishnah taught that any movable object brings impurity to cause anything under it to become impure due to Ohel if it has the thickness of a plow.

Explanation: The impurity of Ohel causes him to be impure for seven days. This is even if there is no law of impurity through connection, for example if there is a kerchief that is separating between the plow and his flesh. In such a case the kerchief is impure for seven days due to the connection of the Ohel with the dead person (see Maharsha who says the text should read "Ohel" not "Adam").

Explanation (cont.): The person is not even impure according to Rabbinic law (for seven days). Rather, he is impure for one night according to Torah law, as is apparent from the Gemara in Nazir (42b). However, they decreed that he should be impure for seven days due to Ohel. This is to prevent people who do not know the laws of connection of impurity to mistakenly say that he is impure for only one night due to Ohel. They might think that since he is only impure due to Ohel for one night due to the object that has the circumference of a Tefach, in general impurity of an Ohel only causes one to be impure for one night.

Explanation (cont.): They therefore decreed that he should be impure for seven days just like a person who is impure in an Ohel ha'Mes. They did not differentiate between whether there are three or four kerchiefs separating between him and the dead person. They did not differentiate between whether the contact he has is four, five, or many more times removed from the dead body. Even if the movable object is a flat wooden vessel that does not become impure, and therefore cannot connect impurity, one is still impure.

Explanation (cont.): However, this is specifically if the item's circumference is that of a plow, which is a Tefach. If it is less than this, there is no mistake that it is because of Ohel. Even if they do not know about impurity through connection, they would not make a mistake. Rather, they would ask why he is impure.

Explanation: Since there is no impurity through connection, a significant Ohel is required like it is regarding other things.

Question: Why did they say he is impure for seven days due to connection according to Rebbi Tarfon? A plow is a simple wooden vessel that does not become impure!

Question (cont.): It must be that the case is where the blade is not in the plow, as if it would be it would cause impurity even if it was very small (much less than a Tefach). Everything under it would be impure due to the law, "A sword is like the dead person" which even applies through impurity of Ohel as is apparent from the Mishnah in Ohalos (1:1). We understand that the entire Pasuk "A dead person with a sword" is meant to teach laws regarding impurity of Ohel, as stated in Nazir (53b).

Answer: Rabeinu Tam answers that the area where the blade is inserted into the plow is considered a "Beis Kibul" - "area that contains." (This takes it out of the category of simple wooden vessels that do not become impure.)

Implied Question: This is not considered a Beis Kibul that is meant to be filled (that is not considered a real Beis Kibul). (Why not?)

Answer: This is because the blade is not permanently set into the wood. Rather, sometimes it is placed in the wood and sometimes it is taken out.

Proof: This is also apparent from Meseches Keilim (25:2) where the Mishnah considers this a Beis Kibul. The Mishnah says, "A plow is considered to have an underside and an inside."

Implied Question: The Mishnah in Keilim (9:6) says that a knitting needle that was swallowed into its wooden shaft or a wooden stick (used to guide oxen that were plowing) that swallowed the metal hook on top of it...if they were pure and they entered an Ohel ha'Mes, they become impure. This means that only the metal hook becomes impure.

Implied Question (cont.): The Mishnah (ibid.) continues that if a loaf of Terumah touched them, it remains pure. This implies that the wooden stick is considered a simple wooden vessel, which is why the loaf of Terumah that touches it is pure. The wooden stick does not become impure from the metal hook. It would seem that the wooden stick discussed in that Mishnah and our case of the wooden plow are similar! (Yet we are saying that the wooden plow is impure by itself!)

Answer: The Ri says that it is possible to say that the case in Keilim (ibid.) is where it is impossible to take the metal hook out of the wooden stick unless one would break the wooden stick. This is why it is no longer considered to have a Beis Kibul.

Explanation: Rabeinu Porat explained that they did not make a decree that the harvesting of olives for the press causes them to become able to become impure.

Explanation (cont.): This is because a decree lest they be harvested in boxes that have tar on the inside (in order to prevent the liquids from spilling out) does not apply to olives, as the liquid that comes out of them at this point is not considered liquid.

Implied Question: The Mishnah in Machshirin (6:5) says that this liquid is considered olive oil. (How can we reconcile this with our explanation?)

Answer: This refers to the liquid that comes out of the olives after they have been sitting together in a container for two or three days after they have been gathered. This is according to the opinion of Rebbi Yaakov later (144b). However, even Rebbi Yaakov admits that liquid that comes out due to the harvest of the olives is pure.

Answer (cont.): Similarly, the reasoning that grapes are very close to each other and regarding a person going out to his field in order to know if his grapes are ripe to be harvested does not apply to olives.

Observation: It is therefore understandable that the Beraisa later (145a) states that if someone crushes some of his olives in order to find out whether his olives are ready to be harvested, they do not become able to become impure.

Explanation: The Tosefta in Machshirin (4:5) says regarding a container containing fruit that water was dripping into that Beis Shamai says the water causes the fruit to become impure. The Tosefta continues that this is only if it (the container) is pure. If it is impure, everyone agrees that it causes the fruit to become impure. These are the words of Rebbi Meir. Rebbi Yosi says that whether it is pure or impure, Beis Shamai says that it causes the fruits to become impure and Beis Hillel says it does not case the fruits to become impure.

Question: The Riva asks, why don't we make a decree regarding growth from Terumas Ma'aser where one cannot take off only a small amount as per the statement of Shmuel?

Answer #1: The Ri answers that it is true that they included Terumas Ma'aser in this decree. The Gemara means that they even made this decree regarding Terumah Gedolah, and it is explaining the reasoning for both Terumah and Terumas Ma'aser.

Answer #2: The Maharam says that the Leviyim are believed regarding Terumas Ma'aser, as Ma'aser is only given to Chaveirim.

Answer #3: The Riva answers that those who were suspect would not take off Terumas Ma'aser at all, as stated in Sotah. The Chaveirim who would take Terumas Ma'aser would be believed [Tosfos Yeshanim].

Explanation: Rashi explains that they therefore decreed that even if he will plant it, it is considered impure.

Question: This is difficult to the Ri. The Gemara in Pesachim (34a) says explicitly that seedlings of impure Terumah are pure from becoming impure and cannot be eaten, meaning they cannot be eaten by a non-Kohen as explained there. This implies it can be eaten by Kohanim!

Answer: Since it cannot be eaten by non-Kohanim, the fact that it has the characteristic of not being impure is not a reason to let him keep it.

Implied Question: In our Gemara we suspect that a bad thing will happen with it, yet in Pesachim (20b) Beis Hillel says one can use impure Terumah wine to spray around the house (on the dirt floor). (Isn't this a contradiction?)

Answer: It is possible to say that Beis Hillel would agree in the case of our Gemara, as sometimes he must keep it around for a full year until he plants it (as opposed to the Gemara there where it can be used immediately).

Question: The Riva asks, why were they more stringent regarding wine, and they said that it is forbidden from benefit, more than their bread or oil?

Answer: He answered that this is because wine causes Hash-m and men to be happy, and they would often pour it for idolatry even when an idol was not present. Accordingly, since Chazal were going to forbid wine anyway in order to prevent intermarriage, the Chachamim gave it the law and stringency of actual Yayin Nesech. This is because they would indeed pour it as a service to their idol, even if an idol was not present.

Observation: The Gemara similarly could have asked, "However, what is there to say according to Rebbi Tarfon?"

Explanation: Rashi considers not ridding one's clothes of lice by the light of a candle and not reading by the light of a candle as two different decrees.

Proof: This is implied by the Beraisas statement, "these (plural) are some of the Halachos" and it only says these two laws.

Implied Question: The Beraisa does not list the prohibition against checking if the clothes are his or his wife's, or for a waiter to check cups and bowls by the candlelight. (Why not?)

Answer: This is because these are derived from the laws regarding lice and reading, as they are the main laws stated.

Question: However, it is difficult why Rashi does not list the prohibition against a Zav eating with a Zavah, as that is certainly one of the eighteen decrees as explicitly stated in the Mishnah!

Explanation #1: Accordingly (Maharam - since we do have to count a Zav eating with a Zavah as one of the eighteen decrees unlike Rashi), it must be that the decree that a person who eats a Rishon or Sheini causes Terumah to be invalid is one decree.

Explanation #2: Alternatively, it must be that one who enters with his head and most of his body into Mayim Sheuvim and a person who is pure that has three Lugin of Mayim Sheuvim fall on him are considered one decree. This is because without one the other would not be true. This is similar to the fact that we consider the decree against Nochri bread, oil, wine, and their daughters as one decree.

Implied Question: The Tosefta states that a Zav who is a Chaver should not eat together with a Zav that is an Am ha'Aretz, and it says, "These are from the Halachos." (We have already listed the eighteen decrees!)

Answer: It is possible to say that this is included in the decree that a Zav should not eat with a Zavah.

Question: This is understandable according to the opinion in Avodah Zarah (36b) that they decreed Yichud applies to a Kusi woman similar to it applying to a Nochris. However, according to the opinion that they decreed the daughters of Kusim were Nidos, how can this decree apply to a Nochris (who is never a Nidah according to Torah law)?

Answer: Since they decreed they were considered Nidos people would refrain from coming in contact with them, and they therefore would not end up marrying them.

Explanation: Rashi explains that they are put in the oven and they turn white.

Proof: This is also implied later (27b) where we state, "the combed pieces of flax, when they turn white."

Implied Question: This is despite the fact that even if one puts out a trap on Shabbos he does not bring a Chatas (i.e. transgress the Torah prohibition of Shabbos) because he does not know if it will end up trapping an animal. (Why should there be a prohibition against doing so on Erev Shabbos if one does even transgress a Torah prohibition if he does so on Shabbos?)

Answer: Even so they decreed that it should be forbidden to do so on Erev Shabbos, as sometimes a person can transgress a Torah prohibition if when he sets the trap he immediately catches something. This is as the Tosefta states that if someone spreads out a net to catch an animal or bird and it flies into the net, he is liable to bring a Chatas.

Question: How does he know when the animal will arrive?

Answer: The Yerushalmi establishes that the case is where he spreads out the trap in forests where there are many animals. The case is additionally where he cannot capture in this net more than one or two animals, as why should it help if he spreads the net out before Shabbos if it will continue to capture animals throughout Shabbos?

Implied Question: This is despite the fact that if he does this on Shabbos he will not have to bring a Chatas (i.e. transgress a Torah prohibition). (Why is it decreed to be prohibited before Shabbos?)

Answer: Since the Nochri is leading the animal or he is doing something that is forbidden according to Torah law on Shabbos, they decreed that this should not be done right before Shabbos. This is as Rashi explains that he will be confused with the one who is his messenger.

Answer (cont.): However, regarding the topics stated in the beginning of the Mishnah where he does not do an action on Shabbos with his hands they would not have made such a decree, were it not for the fact that he is liable to bring a Chatas. This is the reason why we do not give skins to a tanner before Shabbos.

Opinion: Rabeinu Tam understood from our Gemara that it is permitted for a Nochri who is a Kablan (meaning a contractor who gets paid for an entire job no matter when he does it or how long it takes) to build a Jew's house on Shabbos.

Proof #1: He brings a proof from the fact that Beis Hillel permits, according to Rav Yosef, to put wheat in a mill before Shabbos and allow it to grind throughout Shabbos. Certainly it is also permitted to have a Nochri contractor do Melachah for you on Shabbos!

Question: This is not a proof, as everyone knows that the mill grinds on its own, and they also know that the wheat was placed there before Shabbos. However, they might say that the Nochri is being paid to do this job specifically on Shabbos!

Proof #2: He also brings proof from the Gemara in Avodah Zarah (21b) where Rabban Shimon ben Gamliel says that a person may rent his field to a Nochri. Why is this? People will say that the Nochri is merely a sharecropper who is choosing to work on Shabbos for his own benefit. Similarly, people will say the Nochri contractor is working on Shabbos for his own benefit!

Implied Question: He says this is a proof, despite the fact that Rebbi Shimon ben Elazar argues on Rabban Shimon ben Gamliel (ibid.).

Answer: This is because we rule like Rabban Shimon ben Gamliel in this regard, as the Stam Mishnah follows his opinion.

Implied Question: The Gemara in Moed Katan (12a) says that contractors within the Techum (i.e. Halachic city limits) are forbidden, but outside the Techum is permitted. (This is seemingly unlike Rabeinu Tam who says one can even do this in the city!)

Answer: Rabeinu Tam understands that the Gemara in Moed Katan (ibid.) is referring to Hilchos Aveilus, which is why it rules stringently.

Question: It appears to me that the Gemara there (ibid.) has opinions that are more stringent regarding Chol ha'Moed than Aveilus. Even the opinions that are more stringent regarding Aveilus than regarding Chol ha'Moed will admit that Shabbos is more stringent than Aveilus!

Opinion #2: The Ri understands that when our Gemara says that it is permitted to give skins to a tanner, it is referring to a movable object. The Nochri does the Melachah with the skins in his own house, and it therefore does not become known that the skins belong to a Jew.

Proof #1: This is also implied in Moed Katan (11b), where it says that if his object is in the hands of others to do, they should not do it in his house but they may do it in their own house. However, when a contractor is building a Jew's house that is connected to the ground it is known to everyone, and therefore it is forbidden when done inside the Techum, as one who sees the Nochri doing so will say the Jew has hired day laborers (for Shabbos).

Proof #2: This is also implied by the Yerushalmi in our chapter. The Yerushalmi says that if Nochri workers are working for a Jew in his house, it is forbidden. If it is in their house, it is permitted. Rabban Shimon ben Elazar says, this is true when they are Kablanim (contractors).