(Beraisa): We are Toleh the Safek Tamei Chalah. We neither eat nor burn it.

Question: What kind of Safek does the Mishnah discuss?

Answer: It discusses a Safek pertaining to Chalah.

Question: What does this mean?

Answer (Abaye and Rava): It teaches about a Safek other than Hochachos, i.e. such as the case of two paths, which is Tamei even regarding Chulin! (One path, we do not know which, has Tum'ah underneath that is Metamei anyone who traverses the path. Reuven walked on one of the paths and touched Taharos;

Version #1 (Tosfos): After he became Tahor (from the Safek Tum'ah), he walked on the other path and touched other Taharos. Since we cannot be Metaher both sets of Taharos (surely, one of them is Tamei), and there is no reason to be Metaher one more than the other, both are considered Teme'im.

Version #2 (Rashi, as understood by Tosfos): Shimon walked on the other path and touched Taharos. Beis Din was asked to rule about both sets of Taharos at the same time. (As above,) we must rule that both are Teme'im.

Version #3 (Me'iri, and Rashi, according to Aruch la'Ner): (There is only one set of Taharos.) The paths are in Reshus ha'Yachid, e.g. a field in winter, when people do not walk through it. Safek Tum'ah in Reshus ha'Yachid is Tamei.) (end of Version #3)

Rather, the Beraisa discusses (doubtfully) supporting (or being supported by) a Zav, which is Metamei Chalah, but not Chulin.

(Mishnah): If a Zav and a Tahor person (Levi) loaded or unloaded a donkey together:

If the objects were heavy, Levi is Tamei. (Rashi - perhaps; Tosfos - surely) he leaned on the Zav or vice-versa;

If the objects were light, Levi is Tahor. We are not concerned lest one of them leaned on the other.

We are Metaher (Rashi - in both cases; Tosfos - in the latter case only) regarding Chulin Al Taharas Terumah, but not regarding Terumah;

Chulin that is Tevel l'Chalah (Chalah was not yet separated) has the same law as Chalah itself.

Question (Mishnah): A Tevulas Yom (she immersed today. She is still slighty Temei'ah until nightfall) may knead a dough, separate a piece (without yet calling it Chalah), put it in a Kli that does not receive Tum'ah, bring it close to the rest of the dough, and declare it to be Chalah;

This is because a Tevul Yom makes (only) a Shelishi l'Tum'ah, and such Tum'ah does not apply to Chulin.

If (Chulin) Tevel l'Chalah were like Chalah, she would be Metamei the dough!

Answer (Abaye): For every (definite) Tum'ah that is Metamei Chulin, Chachamim decree that (even) Safek cases are Metamei Tevel l'Chalah;

Since a Tevul Yom is not Metamei Chulin, Chachamim did not decree (in any case) that he is Metamei Tevel l'Chalah.

Question: Since a definite Nidah is Metamei Chulin, Chachamim should have decreed that the Safek case (the 24 hours of retroactive Tum'ah) is Metamei Tevel l'Chalah!

(Rav Shmuel bar Rav Yitzchak): The 24 hours apply to Chulin Al Taharas Kodesh, but not to Chulin Al Taharas Terumah.

Answer #1: Chulin Al Taharas Terumah does not contain Terumah within it, but we consider Tevel (l'Terumah or l'Chalah) as if it contains Terumah (or Chalah, i.e. whatever will be separated from it).

Answer #2: Since the 24 hours is only a stringency mid'Rabanan (and at the time she touches Taharos, we have no grounds to suspect that she is Teme'ah), so Chachamim did not decree.

(Mishnah - R. Eliezer): Four types of women are Dayan Sha'atan (because they are Mesulakos Damim, they normally do not see blood) -- a Besulah, a pregnant woman, a nursing woman, and a Zekenah (all of these will be explained).

R. Yehoshua: I heard only that a Besulah is Dayah Sha'atah.

However, the Halachah follows R. Eliezer. (Eliyah Rabah - the Mishnah says this, and not R. Yehoshua.)

(For this Halachah,) a Besulah is a girl who has never seen blood, even if she is married.

A pregnant woman is Dayah Sha'atah from the time the fetus shows;

A nursing woman is Dayah Sha'atah until she weans her baby;

R. Meir says, if another woman is nursing her baby, or if she (prematurely) weaned him, or he died, the 24 hours apply to her;

Chachamim say, she is Dayah Sha'atah.(for the normal period of nursing, 24 months).

A Zekenah is a woman who did not see blood for three periods close to her old age (this will be explained);

R. Eliezer says, any woman who did not see blood for three periods is Dayah Sha'atah.

R. Yosi says, a pregnant or nursing woman is Dayah Sha'atah after three periods without blood.

She is Dayah Sha'atah the first time she sees. The 24 hours apply to the second sighting;

If her first sighting was due to Ones, she is Dayah Sha'atah for her second sighting.

(Gemara - Beraisa - R. Eliezer): You (R. Yehoshua) heard about only one (type of) woman. I heard about many. One who did not see the new moon should not testify about it, rather, only one who saw!

During R. Eliezer's lifetime, people conducted themselves like R. Yehoshua. After R. Eliezer died, R. Yehoshua returned the law (to be like R. Eliezer) like it used to be.

Question: Why didn't he do so in R. Eliezer's lifetime?

Answer: R. Yehoshua was concerned that if people will follow R. Eliezer here, they will follow his rulings elsewhere. We do not want this, because he was Shemuti. (Tosfos - he was from Beis Shamai. Rashi - he was excommunicated);

In R. Eliezer's lifetime, R. Yehoshua would not be able to protest (if people would rule like him in other laws), due to R. Eliezer's honor. After his death, he could protest.

(Shmuel): The Halachah follows R. Eliezer in our Mishnah and in three other places. (After the seven days of Nidah, the next 11 days are called Yemei Zivah. If a woman sees blood for three consecutive days amidst the 11, she becomes a Zavah, and she must count seven consecutive clean days (without blood) before she can immerse and become Tehorah);

(Beraisa - R. Eliezer): If a woman saw Dam Zivah three consecutive days amidst Koshi (labor pains) and ceased Koshi for 24 consecutive hours before giving birth, (we do not attribute the blood to the birth, and) she is Yoledes b'Zov (a Zavah who gave birth);

The Halachah follows R. Eliezer.

(Mishnah - R. Eliezer): If a Zav (or Zavah) checked himself (or herself) on the first and seventh days that he (or she) must count, and found himself (herself) to be clean, and did not check on the other days, we rely on Chazakah that also the intermediate days were clean;

R. Yehoshua says, only the two days checked count. Five more clean days are required;

R. Akiva says, only the seventh day counts;

R. Shimon and R. Yosi say, R. Eliezer's opinion is more reasonable than R. Yehoshua's. (Since R. Yehoshua does not rely on Chazakah, he should be concerned lest an intermediate day was not clean. The first day should not count!)

R. Akiva's opinion is the most reasonable. (We must be concerned lest an intermediate day was not clean. We require seven consecutive clean days.) However, the Halachah follows R. Eliezer.

(Mishnah - R. Eliezer): Achorei Kelim (the backs of Kelim that became Tamei through liquids) are Metamei liquids, even Chulin. They are not even Posel (solid) food; even Terumah.

R. Yehoshua says, a Kal va'Chomer teaches that they are Metamei liquids and are Posel food;

A Tevul Yom is not Metamei Chulin liquids, but he disqualifies Terumah food. Achorei Kelim are Metamei Chulin liquids, all the more so they are Posel Terumah food!

R. Eliezer: Tum'as Tevul Yom is mid'Oraisa, but Achorei Kelim is mid'Rabanan. We cannot use a Torah law to teach about a mid'Rabanan law through Kal va'Chomer!

Mid'Oraisa, food or drink cannot be Metamei a Kli. Chachamim decreed that liquids can be Metamei Kelim, due to fluids (e.g. urine and spit) of a Zav or Zavah, which can be Metamei Kelim;

They decreed that if a liquid was Metamei a Kli, the Kli can be Metamei liquids, but not foods, because liquids are more prone to become Tamei. (A food can become Tamei only after Hechsher, i.e. one of the seven special liquids was put on it. Liquids do not need Hechsher.)

Question: Why do they discuss the back of a Kli, and not the inside of a Kli?

Answer: The back is more lenient. (R. Eliezer admits that the inside is Metamei Terumah food.)

(Mishnah): If a Tamei liquid touched the back of a Kli, the back is Tamei, but the inside, handles, and brim are Tahor;

If a Tamei liquid touched the inside, the entire Kli is Tamei.

Question: What is Shmuel's Chidush? In three of these, the Mishnah or Beraisa itself says that the Halachah follows R. Eliezer!

Suggestion: His Chidush is the Mishnah of Achorei Kelim, which does not say that the Halachah follows R. Eliezer.

Rejection: If so, he only needed to say that the Halachah follows R. Eliezer in that Mishnah!

Answer: Shmuel teaches that (Maharsha - had to teach this, because) we do not derive the Halachah from a Mishnah or Beraisa, even if it says whom the Halachah follows. (Rashba - this is when it opposes a general rule, such as here, for normally the Halachah does not follow R. Eliezer.)