since it is her nature to see blood flow from her body at regular intervals, we do not say: Establish her in her presumptive status of ritual purity. Her body is constantly changing, and therefore she has no such presumptive status.

With regard to the opinions of both Shammai and Hillel, the Gemara asks: And in what way is this case different from that of a ritual bath? As we learned in a mishna (Mikvaot 2:2): In the case of a ritual bath that was known to have contained the requisite forty se’a, which was then measured and found lacking in its quantity of water, all pure items that had been rendered pure in it, i.e., any impure items that had been purified through immersion in this ritual bath, retroactive to when the ritual bath was last measured, whether this ritual bath is found in the private domain or in the public domain, are impure.

The Gemara explains: According to the opinion of Shammai, the mishna poses a difficulty from its statement that the change in the ritual bath’s status is assumed retroactive to the time when it was last measured, as he maintains that a menstruating woman’s status changes only at the present moment, not retroactive to the last time she examined herself.

According to the opinion of Hillel, the mishna also poses a difficulty with regard to its ruling that the items purified in the ritual bath are deemed impure with certainty, whereas a menstruating women does not assume retroactive impurity with certainty. In other words, although according to the Rabbis there is a twenty-four-hour period of retroactive ritual impurity in the case of a menstruating woman, and according to Hillel the retroactive impurity extends back to her most recent examination, nevertheless any teruma that she touched during that period is not deemed definitely impure to the extent that it must be burned. Rather, the impure status of the items she touched is uncertain and the status of the teruma is suspended, i.e., one may neither eat it nor burn it. Whereas here, in the case of the ritual bath, any item purified in it is retroactively deemed definitely impure.

The Gemara answers: There, in the case of a ritual bath, it is different, since it can be said: Establish the impure item in its presumptive status and say that it was not properly immersed. In other words, the presumptive status of the item as ritually impure is in keeping with the current deficient state of the ritual bath. The Gemara raises a difficulty: On the contrary, one should establish the ritual bath in its presumptive state of validity and say that the ritual bath was not previously lacking the requisite measure of water. The Gemara responds: There is no presumptive state of validity, as the ritual bath is lacking before you, i.e., at present, and this offsets the presumptive status that it was full.

The Gemara raises a difficulty: Here too, in the case of a menstruating woman, she is one who has experienced a discharge of blood before you, i.e., at present. Just as the ritual bath’s presumptive status of validity is offset by its present lack of the requisite measure of water, so too the woman’s previous presumptive status of ritual purity is offset by her present state of impurity due to menstruation. The Gemara answers: In the case of the menstruating woman, it is possible that it is only now that she saw the first emission of her menstrual blood. The Gemara retorts: One can say the same with regard to the ritual bath: Here too, it is only now that it became lacking in the requisite measure of water.

The Gemara answers: How can these cases be compared? There, in the case of the ritual bath, it can be said that the water slowly trickled out and consequently the amount of water was continuously diminishing. Therefore, it is possible that the ritual bath lost its valid status long ago without anyone realizing. By contrast, here, with regard to a menstruating woman, can it be said that she was continuously seeing menstrual blood? The Gemara responds: And what is the difficulty? The same possibility does in fact exist in the case of a menstruating woman, as perhaps she saw the blood depart bit [hagas] by bit.

The Gemara states a different answer: There, in the case of the ritual bath, there are two factors that weaken the suggestion that the items are ritually pure: First, the ritual bath is lacking at present; second, the item has a presumptive status of impurity. Here, by contrast, there is only one factor that weakens the possibility that the items touched by the currently menstruating woman were rendered ritually impure, i.e., that she is currently experiencing a menstrual flow. Therefore, according to Shammai she assumes impurity status only from that moment onward, and according to Hillel her retroactive impurity status applies only as an uncertainty.

§ The Gemara asks: And according to Shammai, who holds that her time is sufficient and there is no retroactive impurity, what is different in the case of a barrel? As it is taught in a baraita (Tosefta, Terumot 2:8): If someone would inspect the contents of a barrel to see if it still contained enough wine to continually mentally separate teruma from it, i.e., to exempt other untithed wine of his until all the wine in this barrel will be teruma, and afterward the contents of the barrel were found to have turned to vinegar, which cannot be set aside as teruma for untithed wine, then for all of the first three days following his most recent inspection, it is definitely considered to have been wine. Therefore, any of the untithed wine for which teruma was separated during those days is tithed.

The baraita continues: From that point forward, i.e., more than three days after the most recent inspection, it is uncertain whether it had already turned to vinegar, and consequently any untithed wine for which teruma was separated during those days remains uncertainly tithed. This poses a difficulty for Shammai, who maintains that there is no such retroactive consideration in the case of a menstruating woman.

The Gemara answers: There, in the case of the barrel, it is different, since it can be said: Establish the untithed produce in its presumptive status, as when it first grew it was definitely untithed, and say it was not amended, i.e., exempted, and its status continues to be untithed produce. The Gemara asks: On the contrary, one should establish the wine in its presumptive status, and say that it had not turned to vinegar.

The Gemara rejects this suggestion: This is impossible, as it is turned to vinegar before you, i.e., at present. The Gemara replies: Here too, in the case of a menstruating woman, one who has experienced a discharge of blood is before you, at present, so what is the difference? The Gemara explains: With regard to the woman, it is possible that it is only now that she saw the beginning of her menstrual blood. The Gemara responds: There too, it is possible that it is only now that it turned to vinegar, but not earlier.

The Gemara again answers: How can these cases be compared? There, in the case of the wine, it can be said that it was continuously turning to vinegar. Therefore, it is possible that the wine turned to vinegar much earlier without anyone realizing. By contrast, in the case of the menstruating woman, can it be said that she was continuously seeing menstrual blood? Once again, the Gemara responds: And what is the difficulty? The same possibility does in fact exist in the case of a menstruating woman, as perhaps she saw the blood depart bit by bit.

The Gemara provides a different answer: There, in the case of the barrel, there are two factors that weaken the suggestion that the wine is tithed: First, it is vinegar at present; second, the wine has a presumptive status that it is untithed. Here, by contrast, there is only one factor that weakens the possibility that the items touched by the menstruating woman were rendered ritually impure, i.e., that she is currently experiencing a menstrual flow.

§ And the Gemara raises a contradiction between the halakha of the barrel and that of the ritual bath: What is different here, in the case of the ritual bath, where the items are definitely impure, and what is different there, with regard to the barrel, where it is only uncertain that the produce remains untithed? In both cases the current situation, that the ritual bath is deficient and the contents of the barrel have turned to vinegar, should lead to a definite status.

The Gemara answers: Rabbi Ḥanina of Sura says: Who is the tanna who taught the halakha of the barrel? It is Rabbi Shimon, who, with regard to a ritual bath also considers it as a matter of uncertainty, rather than as definitely impure. Therefore, there is no contradiction between the two halakhot.

As we learned in a mishna (Mikvaot 2:2): In the case of a ritual bath that was known to have contained the requisite forty se’a, which was then measured and found lacking in its quantity of water, all pure items that had been rendered pure in it, i.e., any impure items that had been purified through immersion in this ritual bath, retroactive to when the ritual bath was last measured, whether this ritual bath is located in the private domain or in the public domain, are impure.

The mishna continues: Rabbi Shimon says: If the impure items were immersed in a ritual bath that was in the public domain, they are deemed pure. But if they were immersed in a ritual bath that was in a private domain, the status of any teruma that touched them is suspended, i.e., it is neither consumed nor burned. Rabbi Shimon holds that even in the case of a ritual bath, the items are not retroactively deemed definitely impure. Rather the status is uncertain, just as in the case of the barrel.