1And with regard to this mishna, Rav Yehuda said that Shmuel said: They taught this halakha only with regard to a woman who normally experiences bleeding fifteen days from her immersion, which are twenty-two days from her sighting of menstrual blood, which means that there, she stands in her days of menstruation.
2And when the mishna states that she deviated from her cycle and experienced bleeding on the twentieth day, it means she experienced bleeding twenty days from her immersion, i.e., twenty-seven days from her previous sighting, not twenty-two. This means that when twenty-two days again elapse from when she usually experiences bleeding, she stands within what is now the eleven days of her ziva . And the mishna teaches that both this, the twenty-second day, and that, the twenty-seventh day, are prohibited, despite the fact that the twenty-second day now stands during her days of ziva . Evidently, we are concerned for an emission of blood during the days of ziva if she is accustomed to experiencing bleeding on that day.
3The Gemara elaborates: And Rav Pappa holds that we count twenty-two days of her menstrual cycle from twenty-two days, i.e., from when she usually begins to menstruate, whereas we count the beginning of the days of menstruation from day twenty-seven, when she actually experiences bleeding. Consequently, the twenty-second day of her normal menstrual cycle falls during the days of ziva , according to the actual day of menstruation.
4Rav Huna, son of Rav Yehoshua, said to Rav Pappa: From where do you know this is the correct reckoning of her days? Perhaps one also counts those twenty-two days from day twenty-seven, such that when twenty-two days again arrive from day twenty-seven, she stands within her days of menstruation. Accordingly, there is no proof from the mishna with regard to a sighting during the days of ziva .
5Rav Huna, son of Rav Yehoshua, adds: And so too, it is reasonable that the twenty-two days are counted from when she actually experiences bleeding. As if you do not say so, then consider the case of this chicken that normally lays an egg on one day and withholds an egg the next day, and lays an egg on the third day and withholds an egg on the fourth day. And the chicken deviated from its routine, so that after laying eggs on the first day and third day, it withheld an egg for two days and then laid an egg on one day, i.e., on the sixth day.
6When this chicken again takes hold of its previous routine and starts laying an egg on one day and withholding an egg on the next, does it take hold of the order of the routine ahead of it, i.e., will it withhold an egg on the next day, or does it take hold of its routine as it was from the outset, so that it will lay an egg on the seventh day, as if there had been no deviation? Perforce it takes hold of the order of the routine ahead of it. Likewise, a woman who deviated from her normal menstrual cycle counts the days of her cycle according to the order of the cycle ahead of her, i.e., from the time that she experiences bleeding.
7Rav Pappa said to Rav Huna, son of Rav Yehoshua: But if so, a question arises with regard to that which Reish Lakish said: A woman fixes a menstrual cycle for herself during the days of her ziva , but a woman does not fix a menstrual cycle for herself during the days of her menstruation, i.e., when she is already a menstruating woman. And Rabbi Yoḥanan says: A woman fixes a menstrual cycle for herself during the days of her menstruation. One could ask: What are the circumstances of this dispute? Rabbi Yoḥanan cannot be referring to a case where all her sightings occurred while she was a menstruating woman, as everyone agrees that a woman’s menstrual cycle is not fixed in such a situation (see 11a).
8Rather, is it not referring to a case where she saw blood on the first of the month; and then again on the fifth of that same month, when she was a menstruating woman; and subsequently she saw blood on the first of the next month and then again on the fifth of that month; and now in the third month she saw blood on the fifth of the month but on the first of the month she did not see blood? In such a situation, the woman experienced an emission of blood on the fifth of the month for three consecutive months.
9Rav Pappa concludes: And it is with regard to this case that Rabbi Yoḥanan says: A woman fixes a menstrual cycle for herself during the days of her menstruation. Although she was not actually a menstruating woman before she experienced bleeding on the fifth day of the third month, this is nevertheless considered a sighting during her days of menstruation. Evidently, one counts her menstrual cycle from the first of the month, despite the fact that she did not actually experience bleeding. Likewise, with regard to the case involving twenty-two days, one counts from when she generally experiences bleeding, not from the day she emitted blood in practice.
10Rav Huna, son of Rav Yehoshua, said to Rav Pappa: These are not the circumstances of the dispute. Rather, this is what Rabbi Yoḥanan said: The dispute is referring to a case where she saw blood on the first of the month; and then again on the first of the next month, and then again on the twenty-fifth day of that month; and again on the first of the next month, which occurs during her days of menstruation. Rabbi Yoḥanan maintains that although she is in her days of menstruation, this sighting on the first of the third month serves to fix her menstrual cycle, as we say with regard to the sighting on the twenty-fifth day of the previous month that it is extra blood that gathered inside her. Therefore, it does not negate her regular cycle.
11The Gemara notes: And likewise, when Ravin and all the sea-farers came from Eretz Yisrael to Babylonia and transmitted statements of Rabbi Yoḥanan, they said this statement of Rabbi Yoḥanan in accordance with the explanation of Rav Huna, son of Rav Yehoshua. .