Explanation #1: Only in such a case [she does not fix a Veses in three months], but if she saw in three months [on the same day every month, e.g.] on the second of the month or the first, all agree that she does not need more, like it says above (39b) if she saw on Rosh Chodesh and Rosh Chodesh... (if she sees the next month on Rosh Chodesh, all would agree that she fixed a Veses).

Even if one month was full (30 days) and one was Chaser (29 days), so the number of days between [the first and second] sightings is not the same [as between the second and third sightings], in any case fixing [the day of] the month causes [the Veses].

When initially there is no Shi'ur in the month so the second is seen after a skipped interval from the first, all agree that the first does not count towards the number [required to make a Veses];

Note: This means that the Veses is not based on which day[s] of the month she saw. It is based only on the intervals between sightings. Therefore, even Rav requires four sightings to establish a Veses, for we need three intervals.

We require that [she sees] three times after the same interval, e.g. if she saw now and the second time 20 days later, and the third time 21 days from the second. This is why it mentioned here the 15th of this month.

Note: Rashash says that the same applies if the third time she saw 20 days from the second sighting, like it says in Tosfos Bava Kama (37b), and so says

Question (against Explanation #1): In Bava Kama (37b), it compares an ox that gored on the 15th of this month, the 16th of the [next] month and the 17th of the [next] month to the argument here;

If so, how does it say there regarding "it saw an ox, and gored [it]. It saw an ox, and did not gore", that the first is part of the count? In such a case, even Rav agrees that the first is not part of the count, since it was not at a [fixed] time of the month or week! (An ox can become Mu'ad to gore on the same day every week.)

Answer: We can distinguish between alternation of days and alternation of oxen (goring).

Explanation #2 (R. Chananel): She fixed a Veses of skipping when she did three times like this order;

E.g. she saw the 15th of Nisan, the 16th of Iyar and the 17th of Sivan, and similarly she saw the 15th of Tamuz, the 16th of Av and the 17th of Elul, and she saw also on the 15th of Tishrei, the 16th of Cheshvan and the 17th of Kislev. From now and onwards, she is concerned for the 15th of this month, the 16th of the second month and the 17th of the third month.

According to Shmuel, she must have three skips, i.e. in the fourth month she sees on the 18th, and the next three months she sees on the 16th, 17th and 18th, and similarly in the third [set of sightings] afterwards. The sighting of the 15th in the first month is not part of the count.

Question: Why did he explain like this? If so, when the Gemara asked "let us say that they argue like Rebbi and R. Shimon ben Gamliel", they do not argue only about the first sighting, rather, about the three sightings of the last skipping, and in the conclusion it means differently! (Rashash - i.e. Rav would not require sightings in the third month. Tosfos could have added that also in the second series, Rav would require only two sightings.)

Why don't three months suffice, like Rashi explained?

Question: Also the 18th should be forbidden when she changed to the 17th, for she skipped (the previous month she saw on the 16th), and this is in a Veses of skipping, like seeing on the 15th of the month and the 16th, for we are concerned for one time (seeing according to this skip)!

Answer (Ri): We are not concerned for a Veses of skipping due to one occurrence (one sighting after this skip. This is considered only one occurrence, for since she used to see on the 15th, it does not count towards a Veses of skipping - Aruch l'Ner, unlike Maharsha and Rashash.)

Explanation (Rashi): We are concerned [to forbid] Bi'ah.

Support: We must explain so, since the Gemara did not explicitly explain that it is for Taharos.

Observation: There is no reason to mention fixing a Veses through three times to [forbid] Bi'ah, for through one time she is forbidden, just if it was fixed three times, we are concerned for it until it is uprooted three times.

Explanation: Beis Hillel do not require consecutive [nights], like it says in the Gemara that a case occurred, and Rebbi gave to her four nights amidst 12 months.

Assertion: It seems that the four nights according to Beis Shamai are even scattered, like according to Beis Hillel.

Explanation: This means that she sees due to Bi'ah. We attribute [all sightings] on the entire following day and the night after it, even if she did not have Bi'ah, to Dam Besulim, even if she is not Nocheres (sees blood only when she stands, or only when she sits on the ground). After this, we do not attribute, since she did not have Bi'ah;

This is like it says above (11b), that if one night passed without Bi'ah [and she saw afterwards], she is Temei'ah;

Rav is more stringent. Only when she is Nocheres on the day after Bi'ah, we attribute blood to the Besulim] on that day and the night afterwards, but not without Nechirah.

Observation: According to texts that say "Al Gabei Kulam v'Ro'eh", we cannot explain "when it is known" to mean that there is a proof. It is not proven at all [that it healed], for she sees!

Explanation: Rather, it means that it is known that we can attribute that the wound healed.

Support: We must say so above (56b) "[if a Kesem was found on a garment... R. Acha says, she should launder it again. If it is not washed away,] it is known that it was from before [the previous] laundering. I.e. we may attribute it to before [the previous] laundering.

Question: In Kesuvos (6b), we ask according to the opinion that forbids Bi'ah [with a Besulah] on Shabbos, since it says here "until Motza'ei Shabbos." It says "doesn't this mean that if he did not [yet] have Bi'ah, he may have Bi'ah?", and answers "no, he [already] had Bi'ah";

The Gemara asks "if he [already] had Bi'ah, what is the Chidush?", and answers that it teaches like Shmuel, who said that a tight opening [one may go through it on Shabbos, even though he will scrape on the sides and widen it].

What was the question "what is the Chidush?" It teaches much, that she did not lose nights, like it says here!

Answer: There, there is a version that Shmuel forbids Bi'ah [on Shabbos] for the first time, and similarly for Rav (the other version says that Rav forbids). We need to answer for Shmuel (that the Chidush is that one may go through a tight opening) if [Shmuel] holds like Levi, that she lost nights.

Implied question: In Kesuvos (6b), we bring this teaching of Shmuel regarding a second Bi'ah!

Answer: Here we say according to the truth, that he permits even the first Bi'ah, which is a bigger Chidush.

Implied question: He does not hold that if there was blood there, it would have come before!

Answer: Even so, he properly holds like Rav Gidal above (11b) that if she ceased to sees due to Bi'ah, and she saw, even due to Bi'ah, she is Temei'ah, for if it were Dam Besulim, it would have come initially, when she had Bi'ah;

She should not have she ceased [to see] due to Bi'ah, since initially he had Bi'ah and found blood, if it is true that more Dam Besulim remained, she should not have ceased [to see] when she had Bi'ah;

However, here we discuss when he had Bi'ah and did not find blood. Therefore, we can say that he had Bi'ah [through Hatiyah] like Shmuel.

Inference: People like Shmuel [who can have Bi'ah through Hatiyah] are not common.

Support: In Chagigah (14b), regarding a Besulah who became pregnant, i.e. they sat her on a barrel [of wine] and the smell does not come [out of her mouth], and through this it is known that she is a Besulah...

We conclude that she is Kosher to a Kohen Gadol, for we can say that she became pregnant through [sitting on semen] in a bathhouse (it is common for men to have emissions there, due to the heat), for this is more common than [men] like Shmuel!

Question: In Kesuvos (6b), it says that most [men] are experts to do Hatiyah!

Answer: Hatiyah in Kesuvos is not a full Bi'ah through which she could become pregnant, like other Bi'os. (Very few men are experts to do a full Bi'ah through Hatiyah.)