(Beraisa): She can become retroactively Teme'ah even when she (properly) finds herself Teme'ah. I.e. not at the time of her Veses she is retroactively Teme'ah 24 hours.

Inference: Because she can become retroactively Teme'ah, her Kesem is retroactively Tamei, but the four women who are Dayan Sha'atan, also their Kesamim are Dayan Sha'atan!

Question: Who is the Tana of the Beraisa?

Answer: It is R. Chanina ben Antignos.

(Rav Yehudah citing R. Chanina ben Antignos): Kesamim of all women (except for the exceptions we will give) are retroactively Teme'im;

Any woman who is Dayah Sha'atah, the law of her Kesem is as if as she (properly) saw blood, except for a girl below the age (at which we expect her) to see blood;

For such a girl, even if her sheet is full of blood, we are not concerned.

Question: R. Chanina ben Antignos is not concerned for Kesamim at all!

(Beraisa): Kesamim of all women are Teme'im, even women who are Dayan Sha'atan.

R. Chanina ben Antignos says, women who are Dayan Sha'atan do not have Kesamim.

Suggestion: This means that their Kesamim are totally Tehorim.

Answer: No, it means that Dayan Sha'atan, but they are Teme'im from now and onwards.

Inference: This implies that the first Tana holds that they are retroactively Teme'im!

Affirmation: Yes! It is R. Meir, who is more stringent about Kesamim (Rashi - than about actual blood; Tosfos - than other Tana'im);

(Beraisa - R. Meir): All Kesamim are retroactively Teme'im, even of women who are Dayan Sha'atan (regarding a proper sighting);

R. Chanina ben Antignos says, the Kesem of a woman who is Dayah Sha'atah is like her blood. (It is Metamei her from now and onwards.)

If a girl is at the age to see blood (even if she never saw yet), her Kesem is Tamei;

If she is not yet at the age, her Kesem is Tahor.

The age to see is the age of Na'arus (Rambam - 12 years and two hairs; Rashi - 12 years or two hairs).

(Mishnah): If Bedikos were done at the time of relations, this limits the law of retroactive Tum'ah (like a Bedikah).

(Rav Yehudah): The Bedikah done before relations does not count as a Bedikah.

Question: What is the reason?

Answer (Rav Ketina): She is hurrying to have relations.

Question: Why does this invalidate the Bedikah?

Answer: Because she is hurrying, she does not insert the cloth into crevices.

Question (Mishnah): If Bedikos were done at the time of relations, this limits the law of retroactive Tum'ah.

Suggestion: Bedikos (plural) teaches that before and after are both valid (to limit retroactive Tum'ah)!

Answer #1: No, it refers to two Bedikos done after. Also he checks himself (lest blood is on his Ever).

(Mishnah): Benos Yisrael do two Bedikos at the time of relations -- one for her, and one for him.

Question: If one of the Bedikos is before relations, we understand the Chidush of our Mishnah. Even though she is hurrying, we rely on the Bedikah;

If the Mishnah discusses Bedikos after relations, what is the Chidush?

Answer: One might have thought that perhaps there was a drop of blood and it was covered by semen. The Mishnah teaches that we are not concerned for this.

Answer #2 (to Question (g)): The Mishnah teaches that Chachamim obligate women to check themselves before and after relations;

The Mishnah also teaches that the Bedikah after relations is considered a Bedikah.

Question: "If Bedikos were done" connotes that they are optional!

Correction: The Mishnah should say "she must do Bedikos."

(Mishnah): (The Bedikah at the time of relations) lessens retroactive Tum'ah from 24 hours or (if a Bedikah was done within this time) from the previous Bedikah.)

Question: If it lessens Tum'ah from 24 hours (Rashi - a large period of time; Tosfos - even though this is when she transgressed, i.e. she omitted the Bedikah of the previous morning or evening), all the more so it lessens from the previous Bedikah!

Answer: One might have thought that Chachamim were concerned for a large loss of Taharos (24 hours, so then they consider it like a Bedikah), but not for a small loss (when the previous Bedikah was within 24 hours.) The Mishnah teaches that this is not so.

(Mishnah): When we say that Dayah Sha'atah...

Question: It would have sufficed to say "if she was handling Taharos." Why does the Mishnah also mention "if she was sitting on a bed"?

Answer: This teaches that if she was not Dayah Sha'atah, also the bed would also be Tamei. It supports Ze'iri;

(Ze'iri): If a woman sat on a Mishkav or Moshav (a Kli made to sit or lie on) during the 24 hours (of retroactive Tum'ah before she found herself to be Nidah), she makes it an Av ha'Tum'ah to be Metamei Begadim. (It is Metamei a person and the garments he wears (or touches) when he sits on or touches it.)

Question: Why would the bed be Tamei? We are Metaher cases of Safek Tum'ah regarding Ein Bo Da'as Lisha'el!

Answer #1 (Ze'iri): The case is, other women were carrying the bed when she was on it. The bed is like their hands (Yesh Bo Da'as Lisha'el).

Answer #2: Even if the bed is on the ground, it is considered Yesh Bo Da'as Lisha'el due to R. Yochanan's law;

(R. Yochanan): Safek cases of Tum'ah that arise through people are Tamei in Reshus ha'Yachid;

Even if the Kli rests on the ground, it is considered Yesh Bo Da'as Lisha'el.

Question (Beraisa): If a man was surrounded by Taharos and Avos ha'Tum'ah, and he cloaked himself with a (Tahor or Tamei) garment, and he is unsure if it touched them, whatever was Tahor remains Tahor;

If it is (Tosfos - almost) impossible that it did not touch, the garment became and/or made the Taharos Teme'im.

R. Shimon ben Gamliel says, we tell him to put it on again to see if it touches when he puts it on.

Chachamim: We do not make such tests (Tosfos - to be lenient) regarding Taharos!

Summation of question: According to R. Yochanan, this should be considered Yesh Bo Da'as Lisha'el. We should always be Metamei!

Answer: Indeed, R. Hoshaya explained that we are Metaher only in Reshus ha'Rabim. We are Metamei in Reshus ha'Yachid (like the law of Yesh Bo Da'as Lisha'el).

(Ze'iri): If a woman sat on a Mishkav or Moshav during the 24 hours (of retroactive Tum'ah), she makes it an Av ha'Tum'ah to be Metamei a person and his garments.

Question (Avimi's Beraisa): During the 24 hours, a Mishkav or Moshav that she sat on is like (a Kli that) she touches.

Suggestion: Just like a Kli that she touches is not Metamei people, also her Mishkav.

Rejection (Rava): A Kal va'Chomer disproves this!

A Kli Cheres with a Tzamid Pasil (it is plastered shut) does not become Tamei in an Ohel with a Mes, but a Nidah is Metamei it retroactively (as if she touched it after seeing blood. We will explain how Rava knew this.) A Mishkav or Moshav, which becomes Tamei in Ohel ha'Mes, all the more so a Nidah is Metamei it retroactively (as if she sat on it after seeing blood, and makes it an Av ha'Tum'ah)!

Question: Avimi cited a Beraisa! (Rava must agree to it.)

Answer to both questions: It means that a Mishkav or Moshav on which she sat is Metamei (one who sits on it) like she is Metamei someone she touches, i.e. she makes him and his clothes Teme'im.