Question (Beraisa - R. Eliezer): If it was lost in the city, the Eruv is valid. If it was lost in the field, the Eruv is invalid;

If it is on Yom Tov [when one may carry], what difference does it make where it was lost?!

Answer: The Beraisa is abbreviated. It means as follows:

If it was in a locked cabinet and he lost the key, the Eruv is valid. (He may break it open);

This is only if it is Yom Tov. If it is Shabbos [he may not, so] the Eruv is invalid.

If the key was found, whether in the city or in the field, it is invalid. (One may not bring it to the cabinet.)

R. Eliezer says, if it was found in the city, it is valid. If it was found in the field, it is invalid.

In the city, it is valid. This is like R. Shimon, who says that roofs, Chatzeros and Karfifos are considered one Reshus for Kelim that were Shoves in them, but not for Kelim that were Shoves in the house.

In the field, it is invalid. This is like Chachamim [of R. Shimon, who forbid passing Tefilin from person to person less than four Amos at a time. R. Yehonason; Bach (on Rif) - it is like Chachamim of Rebbi, who forbid Shevus Bein ha'Shemashos. Hagahos ha'Bach on the Daf deletes 'this is like Chachamim' from the text.]

Answer #2 (to Question 4:c, 34b - Rabah and Rav Yosef): The Mishnah discusses a wooden cabinet;

The first Tana holds that it is a Kli. [The Melachos of] building and destroying do not apply to Kelim (therefore one may break it open);

R. Eliezer holds that it is an Ohel (tent, so one may not destroy it).

They argue like the following Tana'im;

(Mishnah (it is also a Tosefta)): If a Zav banged on a coach, box or cabinet, it becomes Tamei. (His skin did not touch it, e.g. he wore a glove or used a stick);

R. Nechemyah and R. Shimon are Metaher.

Suggestion: The first Tana holds that these are Kelim. R. Nechemyah and R. Shimon hold that they are Ohalim [and are not Mekabel Tum'ah].

Rejection (Abaye - Beraisa): [If a Zav banged] an Ohel and it moved, it is Tamei. [If he banged] a Kli and it did not move, it is Tahor. (Rashi - even an Ohel is Mekabel Tum'ah. Rambam, according to Grach (409) - all agree that Ohalim are not Mekabel Tum'ah. All references here to Ohalim refer to the Kelim inside.)

(Seifa of the Tosefta): If it moved, it is Tamei;

The general rule is, if the Zav moved it, it is Tamei. If vibrations moved it (e.g. the Zav stomped on the floor), it is Tahor. (It did not move due to his [direct] Ko'ach (impetus), rather, due to Ko'ach Kocho.)

(Abaye): All agree that if the Zav moved it, it is Tamei. If vibrations moved it, it is Tahor;

They argue in a case when the Zav banged it and it vibrated. The first Tana considers this as if the Zav moved it. R. Nechemyah and R. Shimon do not.

Question: If so, how do we explain our Mishnah?

Answer #3 (Abaye and Rava): The case is, the lock is tied with ropes, and one needs a knife to break them. The first Tana holds like R. Yosi, who permits moving any Kli on Shabbos, except for a big saw or the blade of a plow;

R. Eliezer holds like R. Nechemyah, who permits moving even a garment or ladle only for its intended purpose. (A knife is not made for cutting rope.)

(Mishnah): If the Eruv rolled outside the Techum, or a pile of rocks fell on it [and buried it], or it was burned, or it was Terumah and it became Tamei:

If this was before Shabbos, the Eruv is invalid. If it happened on Shabbos, it is valid.

R. Meir and R. Yehudah say, if we are in Safek whether it was before or on Shabbos, he is in Chamar Gamal (like one prodding a donkey from the back and leading a camel from the front, i.e. he must face both ways. If the Eruv was 1000 Amos to the north, it forbids him to go more than 1000 Amos to the south, lest the Eruv was valid, and he may not go past 2000 Amos to the north lest it was invalid.)

R. Yosi and R. Shimon say, a Safek Eruv is valid.

R. Yosi: Avtulmus testified in the name of five Chachamim that a Safek Eruv is valid.

(Gemara - Mishnah): If the Eruv rolled outside the Techum...

(Rava): This is only if it rolled more than four Amos outside the Techum. If it is within four, it is valid, for we 'give' four Amos to one who places an Eruv. (It is as if it is within the Techum.)

(Mishnah): If a pile of rocks fell on it...

We are thinking that he could [physically] remove the rocks. (It is forbidden only because they are Muktzeh.)

Suggestion: Our Mishnah is unlike Rebbi, who permits Shevus Bein ha'Shemashos.

Rejection: It is even like Rebbi. The case is, one needs [to dig with] a hoe and axe to uncover it. (It is in his land. He would be liable for plowing even if he does not need to plow now.)

We must teach both of these;

Had it taught only about rolling outside the Techum, we would have thought that it is invalid because it is not near him, but if it is covered by rocks, it is valid;

Had it taught only about being covered by rocks, we would have thought that it is invalid because it is covered, but if it rolled outside, since the wind could bring it back, it is valid.

(Mishnah): Or if it was burned, or it was Terumah and it became Tamei...

Question: Why do we need these cases?

Answer: A burned Eruv teaches the extremity of R. Yosi's opinion [that a Safek Eruv is valid even if it is not in the world]. Tamei Terumah teaches the extremity of R. Meir's opinion. (Rashi - he is Posel even though it is here and it had Chezkas Taharah. Rashash - he is Posel even though Safek Tum'ah in Reshus ha'Rabim is normally Tahor.)

Question: R. Meir is lenient about a Safek [mid'Rabanan]! (A Stam Mishnah is R. Meir.)

(Mishnah): If a Tamei person went to immerse and has the following doubts, he is Tamei:

He is unsure whether or not he immersed, and (Ritzva - or) whether or not the Mikveh had 40 Sa'im, or there are two Mikva'os, only one of which has 40 Sa'im, and he is unsure in which he immersed.

This is when he became Tamei mid'Oraisa. If he was Tamei mid'Rabanan and had the same doubt about immersion, he is Tahor;

Tum'os mid'Rabanan include one who ate or drank Tamei food or drink, one [who immersed from Tum'ah today, i.e. a Tevul Yom] who entered Rosho v'Rubo (his head and the majority of his body) in Mayim She'uvim (water that was in a Kli. Even after nightfall, he is Posel Terumah until he immerses again), or [anyone] who had three Lugim of Mayim She'uvim poured on Rosho v'Rubo.

R. Yosi is Metamei.

Answer: R. Meir holds that Eruv Techumim is mid'Oraisa.

Question: This is not true!

(Mishnah): (When measuring the Techum, two people hold a 50 Amah rope by its ends. We count the distance between them to be 50 Amos, even if valleys and inclines in between make the 'walking' distance (i.e. along the incline) to be more than this.) If there is a hill in between which cannot be 'swallowed' by the rope:

R. Dostai says in the name of R. Meir, I heard that [we do not measure with the 50 Amah rope along the slope, rather,] Mekadrin. (Two people hold a four Amah rope by its ends. One holds it near his feet, and the other holds it near his head. This reduces or cancels out the vertical component of the distance. It is as if we drilled through the hill to measure the horizontal distance.)

We would not be so lenient if Techumim were mid'Oraisa!

(Rav Nachman): We do not Mekader when measuring the Techum of an Ir Miklat (city of refuge for Shogeg murderers. Also the Techum gives refuge) or when measuring [the nearest city to a murdered body] to bring Eglah Arufah [a calf beheaded to atone for the murder], because they are mid'Oraisa.

Answer: R. Meir said 'Mekadrin' in the name of his Rebbi, but he himself holds that Eruv Techumim is mid'Oraisa.

Support (Mishnah): ... I heard that Mekadrin...

Question: R. Meir contradicts himself regarding mid'Oraisa laws! (Elsewhere he follows Chazakah to be lenient about Safek Tum'ah.)

(Mishnah - R. Meir): If Reuven touched Shimon at night, and did not know then if he was alive, and the next morning he found Shimon dead, Reuven is Tahor;

Chachamim say, he is Tamei, for we assume that Tum'os were previously in the same state that they were found in.

Answer #1 (R. Yirmeyah): In our Mishnah, [R. Meir is stringent because] a Sheretz was on the Eruv all of Bein ha'Shemashos.

Question: If so, R. Yosi would not be Machshir!

Answer (Rabah and Rav Yosef): The case is, one set of witnesses says that it became Tamei during the day, and another set says that it became Tamei after dark. (R. Yosi holds that the contradictory testimonies cancel each other, and the Chezkas Taharah remains. R. Meir says that the testimonies create a Safek. Tosfos (Sof 83a) - Rabah and Rav Yosef explain R. Yirmeyah. (I.e. the first pair says that a Sheretz was on the Eruv all of Bein ha'Shemashos. If R. Yirmeyah were rejected, the Gemara would have said 'Ela'.))