(Mishnah): A woman is Muchzekes Tehorah during the 11 days of Zivah;

If she did not check herself, whether she forgot, was unable, or intentionally did not check, she is Tehorah;

If her Veses came and she did not check herself, she is Teme'ah;

R. Meir says, if she was hiding (from an invading army or bandits) and her Veses came and she did not check herself, she is Tehorah, for fear inhibits blood;

A Zav (during the days he must count), Zavah or Shomeres Yom k'Neged Yom is Muchzak to be Tamei.

(Gemara) Question: What do we learn from the first law?

Answer #1 (Rav Yehudah): She need not check herself.

Question: The next clause says "if she did not check herself... " This implies that l'Chatchilah, she must!

Answer: That clause refers to Yemei Nidah (after the 11 days, when a sighting would make her a Nidah);

During the 11 days she is Muchzekes to be Tehorah, so she need not check. During the days of Nidah, she must check herself. If she did not, whether she forgot, was unable, or intentionally did not check, she is Tehorah.

Answer #2 (Rav Chisda): The Chidush of the Reisha is according to R. Meir, who forbids a woman without a Veses to have Bi'ah;

This is only during Yemei Nidah, but during Yemei Zivah she is Muchzekes Tehorah.

Question: If so, why does R. Meir require her husband to divorce her and never remarry her?

Answer: We are concerned lest he have Bi'ah with her during Yemei Nidah.

Question (Seifa): If her Veses came and she did not check herself, she is Teme'ah.

This implies that that she has a Veses!

Answer: The Mishnah is abbreviated, it means as follows:

A woman is Muchzekes Tehorah during the 11 days of Zivah, and she is permitted to her husband. During the days of Nidah, she is forbidden;

This refers to a woman without a Veses. If she has a Veses, she is permitted even during the days of Nidah, and she must check herself;

If she did not check herself, whether she forgot, was unable, or intentionally did not check, she is Tehorah;

If her Veses came and she did not check herself, she is Teme'ah.

Question: Since the Seifa is R. Meir, the beginning is not!

Answer: The entire Mishnah is R. Meir. It means as follows:

If she was not hiding and her Veses came and she did not check herself, she is Teme'ah, for R. Meir says that if she was hiding, she is Tehorah, for fear inhibits blood;

Answer #3 (Rava): The Reisha teaches that the 24 hours of retroactive Tum'ah do not apply during the 11 days.

Rejection (Beraisa): The 24 hours apply to all of the following: (a woman when she first becomes) a Nidah, Zavah, Shomeres Yom k'Neged Yom, and a Yoledes. (Aruch la'Ner - every Zavah was initially a Shomeres Yom k'Neged Yom, so there was no need to teach Zavah! Indeed, the Mishnah teaches that the 24 hours apply not only to (one who became a) Zavah (retroactively, we know that she was Muchzekes to see blood), but even to a Shomeres Yom who saw only once.)

Rava is refuted.

Answer #4 (Rav Huna bar Chiya citing Shmuel): It teaches that she cannot fix a Veses during the 11 days.

Rav Yosef: I never heard this (from my Rebbi, Rav Yehudah, who was a Talmid of Shmuel)!

Abaye: You taught this law to us (before you forgot your learning), to explain a Mishnah!

(Mishnah): If a woman always used to see on day 15, and once she saw on day 20, she is forbidden to have Bi'ah on (the coming) days 15 and 20 (lest she become a Nidah then);

If next time she saw again on day 20, she is forbidden on days 15 and 20;

(Rav Yosef citing Rav Yehudah citing Shmuel): The Mishnah refers to the 15th day after she may immerse (i.e. after the seven days of Nidah), i.e. 22 days after becoming a Nidah. It could not mean day 15 after becoming a Nidah, for this is during the 11 days of Zivah, and a woman cannot fix a Veses during these days.

Question (Rav Papa): Granted, one of the 11 days cannot be a fixed Veses (to be forbidden until she uproots (ceases to see on) it three times). Is it forbidden before she uproots it once?

Rav Yehudah of Diskarta could not answer.

Answer (Rav Papa): The Mishnah says, if she used to see on day 15, and once she saw on day 20, days 15 and 20 are forbidden;

(Rav Yosef citing Shmuel): The Mishnah refers to day 15 after she may immerse. (Surely, "day 20" means 20 days after she may immerse, i.e. 27 days from the previous sighting.)

Rav Papa: Because she normally sees every 22 days, days 22, 44,... are forbidden. Now, because she saw on day 27, she is also concerned for 27 days from her Veses (day 22), i.e. day 49;

Even though day 44 is only 17 days after this sighting (on day 27), and is within Yemei Zivah, it is forbidden!

Rejection (Rav Huna brei d'Rav Yehoshua): Perhaps she is concerned for days 22 and 27 from her sighting (on day 27), which are after Yemei Zivah.

Support: Surely, this is correct. If a chicken normally lays an egg every other day, and once it did not lay an egg until the third day, surely, we expect it to next lay an egg two days from this egg, not two days from when it should have laid (yesterday). Likewise, a woman expects to see after her Veses (i.e. normal interval between the beginning of Nidah until the next beginning of Nidah) after this sighting!

Question (Rav Papa): Reish Lakish and R. Yochanan are concerned for a Veses within Yemei Zivah!

(Reish Lakish): A woman can fix a Veses in Yemei Zivah, but not in the (last six) days of Nidah (for blood in the last six days is a mere continuation of the sighiting that made her a Nidah);

(R. Yochanan): She can fix a Veses in the (last six) days of Nidah.

Suggestion: The case is, she became a Nidah on Rosh Chodesh, and saw blood also on the fifth of the month (within the days of Nidah). She next became a Nidah on the next Rosh Chodesh, and saw also on the fifth; she did not see the following Rosh Chodesh, but saw on the fifth;

This is called fixing a Veses in the days of Nidah, because we count from when she expected to see (on Rosh Chodesh), so the fifth is considered in the (last six) days of Nidah (even though it actually began Nidah)!

Answer (Rav Huna brei d'Rav Yehoshua): No. The case is, she became a Nidah on Rosh Chodesh, and also on the next Rosh Chodesh; she next became a Nidah on the 25th of the month; and saw five (or six) days later on Rosh Chodesh. (The third sighting, which fixes the Veses, was in the days of Nidah. Reish Lakish holds that she does not fix a Veses, for what she saw on Rosh Chodesh was only due to becoming a Nidah on the 25th;)

R. Yochanan says, she fixes a Veses. Her primary sighting was on Rosh Chodesh, as usual. What she saw on the 25th was merely extra blood that came early due to her primary sighting. (Her primary sighting was Rosh Chodesh only regarding fixing a Veses. She counts the days of Nidah and Zivah from the 25th.)

Ravin and other Chachamim of Eretz Yisrael who came to Bavel explained like Rav Huna.