And as for the ruling of the baraita, that a woman who discovers menstrual blood not at her fixed time for menstruation is impure retroactively, this is a halakha with which everyone agrees.

The Gemara raises a difficulty: But let us interpret the mishna in the opposite manner. Why interpret the mishna in accordance with the opinion of Rabbi Dosa and the baraita in accordance with everyone, when we can give precedence to the mishna, which is more authoritative, by interpreting it in accordance with all opinions, as was first explained, and the baraita only in accordance with the opinion of the Rabbis.

The Gemara answers: Since there is a way to interpret it as a leniency, i.e., that all agree that blood discovered at the fixed time of menstruation renders items impure only from that point onward, and it can also be interpreted in a manner that leads to a stringency, i.e., everyone agrees that blood discovered not at her fixed time for menstruation causes retroactive impurity, and furthermore the Rabbis hold that this is the halakha even when blood is discovered at her fixed time of menstruation, we interpret it the way that leads to a stringency.

§ It is taught in the baraita: If a woman who has a fixed menstrual cycle finds a blood stain, her blood stain is retroactively impure. The reason is that if she sees a flow of menstrual blood not at the fixed time of her menstrual cycle, it renders her ritually impure retroactively for a twenty-four-hour period. The Gemara analyzes this statement: The reason for this ruling is that she is a woman who has a fixed menstrual cycle; therefore, the Rabbis distinguish between her blood stain, which causes retroactive impurity like a sighting not at her fixed time, and her sighting of her menstrual flow at its fixed time, which does not cause retroactive impurity.

It can be inferred from here that in the case of those other women, e.g., a pregnant or elderly woman, with regard to whom the Sages stated: Their time is sufficient and their menstrual flow never causes retroactive impurity, the same halakha applies to their blood stains as to their sighting of their menstrual flow, i.e., the stains do not cause retroactive impurity.

The Gemara asks: In accordance with whose opinion is this baraita taught? The Gemara answers: It is in accordance with the opinion of Rabbi Ḥanina ben Antigonus, as Rav Yehuda said that Shmuel says in the name of Rabbi Ḥanina ben Antigonus: The halakha with regard to all women is that their blood stains are impure retroactively. But any women with regard to whom the Sages stated: Their time is sufficient, their blood stains share the same ruling as their sighting of their menstrual flow, i.e., they do not cause retroactive impurity. This is the halakha except for the case of a young girl whose time to see the flow of menstrual blood has not arrived. With regard to her, even if her sheets are soiled with blood one need not be concerned for it, i.e., her blood stains do not cause any impurity at all, even from that point onward.

The Gemara asks: And does Rabbi Ḥanina ben Antigonus hold that a blood stain causes ritual impurity at all? But isn’t it taught in a baraita: The halakha with regard to all women is that their blood stains are impure. And similarly, women with regard to whom the Sages stated: Their time is sufficient, their blood stains are also impure. Rabbi Ḥanina ben Antigonus says: The halakha of women with regard to whom the Sages stated: Their time is sufficient, is that they do not have the ritual impurity of a blood stain. What, is it not correct to say that this means they have no impurity caused by a blood stain at all? The Gemara answers: No, it means that they do not have impurity caused by a blood stain retroactively, but they do have the impurity caused by a blood stain from here onward.

The Gemara asks: From the fact that Rabbi Ḥanina ben Antigonus holds that a blood stain imparts ritual impurity from that point onward, does this not indicate that the first tanna holds that it causes ritual impurity even retroactively? The Gemara answers: Yes, the ruling of the first tanna is in accordance with the opinion of Rabbi Meir, who is stringent with regard to blood stains. As it is taught in a baraita: The halakha with regard to all women is that their blood stains are impure retroactively. And similarly, women with regard to whom the Sages stated: Their time is sufficient, their blood stains are also impure retroactively. This is the statement of Rabbi Meir.

The baraita continues: Rabbi Ḥanina ben Antigonus says: The halakha of women with regard to whom the Sages stated: Their time is sufficient, is that their blood stains share the same ruling as their sighting of their menstrual flow, i.e., they cause ritual impurity from that point onward. And in the case of a young girl, if her time to see the flow of menstrual blood has arrived, then she has impurity status when she finds a blood stain. But if her time to see the flow of menstrual blood has not yet arrived, she does not have impurity status when she finds a blood stain. The Gemara asks: And when does a young girl arrive at her time to see the flow of menstrual blood? The Gemara answers: When the days of her young womanhood have arrived.

§ The mishna teaches: And with regard to a woman who engages in intercourse while using examination cloths, with which she ascertains whether the menstrual flow began, since the halakhic status of that act is like that of an examination, it reduces the time from a twenty-four-hour period and reduces the time from examination to examination. Rav Yehuda says that Shmuel says: The examination cloth with which she examined herself before intercourse does not reduce the time from a twenty-four-hour period like a regular examination.

The Gemara asks: What is the reason for the opinion of Shmuel? Rav Ketina says: Since she is excited [shemehuma] and hurried for intercourse with her husband, it is not considered a proper examination. The Gemara asks: And even if she is excited for intercourse with her husband, what of it? Why does that invalidate her examination? The Gemara answers: Since she is excited and hurried for intercourse with her husband, she does not insert the examination cloth into her recesses and folds.

The Gemara raises a difficulty: We learned in the mishna: And a woman who engages in intercourse while using examination cloths, the halakhic status of that act is like that of an examination. The mishna refers to examination cloths in the plural. What, is it not speaking of one cloth used before intercourse and one cloth used after intercourse? The Gemara answers: No, this cloth and that cloth are both used after intercourse; and the reason why the mishna uses the plural is that one cloth is for his use and one is for her use. As we learned in a mishna (14a): It is the custom of Jewish women to engage in intercourse with their husbands with two examination cloths, one for his use and one for her use.

The Gemara asks: What is this? Granted, if you say that the mishna is referring to one cloth used before intercourse and one used after intercourse, it was necessary for the mishna to mention both examinations, as it might enter your mind to say that since she is excited and hurried for intercourse with her husband, she did not examine herself properly. Therefore, the mishna teaches us that her examination with a cloth before intercourse is considered as a halakhically valid examination. But if you say that this cloth and that cloth are his and her cloths used after intercourse, isn’t it obvious that they are treated as halakhic examinations? Why is this ruling necessary?

The Gemara answers: The halakha that the examinations performed after intercourse count as valid examinations is necessary, lest you say that perhaps she might see a drop of blood corresponding to the size of a mustard seed and a drop of semen covered it. In other words, it is possible that she discharged a tiny amount of menstrual blood that went undetected, as it was covered by a drop of semen. Therefore, the mishna teaches us that one does not need to be concerned for this possibility.

And if you wish, say instead: The mishna is referring only to her examinations, but the reason the mishna mentions two examinations is not to give them the status of valid examinations, but to teach that they are both obligatory. As the Sages required her to perform two examinations: One before intercourse and one after intercourse. And when the mishna teaches: The halakhic status of that act is like that of an examination, it is referring specifically to the examination performed after intercourse. The Gemara raises a difficulty: But the mishna teaches: A woman who engages in intercourse while using examination cloths. This formulation indicates that the examination is voluntary and is not mandated by the Sages. The Gemara explains that one should emend the text of the mishna so that it teaches: And a woman must engage in intercourse while using examination cloths.

§ The mishna teaches: And with regard to a woman who engages in intercourse while using examination cloths, as the halakhic status of that act is like that of an examination, it reduces the time from a twenty-four-hour period, and reduces the time from examination to examination. The Gemara asks: Now that the mishna teaches that this examination reduces time from a twenty-four-hour period,