The discussion begins with a question posed in yesterday's folio regarding a woman who experienced a doubtful discharge, a safek re'iyah. If her husband returned home and it was uncertain whether she had seen blood or immersed in a ritual bath, she is permitted to her husband without further inquiry. This leniency applies even if it is certain she saw blood, but doubtful whether she immersed. However, in a case of a definite sighting (vadai ra'ata), where it is known she saw blood, and there is only one doubt—whether she immersed in the ritual bath—we do not apply leniency. The principle is that a doubt cannot resolve a certainty. This raises a challenge: why is this different from the case of a wise man (chacham) who died leaving produce that was definitely untithed (vadai tevel), but it is doubtful whether he tithed it (safek itok)? In that case, we are lenient, assuming he did tithe it, thereby resolving the certainty with a doubt.
The first answer given by the Gemara is that the case of the chacham is not a true doubt. A chacham would certainly not leave untithed produce in his house; thus, it is a certainty that he tithed it. Therefore, it is a certainty of untithed produce and a certainty of tithed produce, not a doubt resolving a certainty.
A second answer is then offered: the case of the chacham involves a "doubt within a doubt" (safek be'safeko). As Fedra b'Hoshaya said in the name of Amar b'Hoshayam, a person can bring produce into their house in a way that exempts it from tithing. For example, by bringing wheat into the house with its chaff still on, it is not yet fully processed and is therefore not subject to the Torah-level obligation of tithing (chiyuv ma'aser de'Oraita), but only to a rabbinic obligation (chiyuv ma'aser de'Rabbanan). In such a scenario, we do not know how the chacham brought the fruit into his house. Perhaps he brought it in with the chaff, meaning there was no definite Torah-level obligation for tithing, only a rabbinic one. Thus, there is a doubt whether he was even obligated to tithe, and a further doubt whether he actually tithed. This "doubt within a doubt" allows for leniency in a rabbinic matter. In contrast, the case of a woman who definitely saw blood (vadai ra'ata) is a Torah-level prohibition (de'Oraita), and we cannot be lenient by saying a doubt about her immersion resolves a certainty of her ritual impurity. The Rashi explains that this is akin to a doubt about whether the chacham was obligated to tithe at all, as he might have brought the produce in an unfinished state, like with the chaff, which is not subject to tithing until fully processed and brought through the front door for storage. This method is often used to feed animals, as animal feed is not subject to tithing requirements in the same way human food is, especially if it does not reach the status of tevel de'Oraita. Therefore, in the case of the chacham, it is a doubt concerning a rabbinic obligation, allowing for leniency, whereas the nidah is a Torah-level prohibition.
The Gemara then challenges this distinction: "Does a doubt not remove a certainty?" The same question is raised again, citing a story from a Baraita. A bully (massik echad) in a place called Rimon had a stillborn baby (nefel) and threw it into a pit. A priest (Kohen) leaned over the pit to determine if the baby was male or female, as this affects the mother's days of ritual impurity. The rabbis declared the Kohen ritually pure, even though he had leaned over a pit containing a nefel, which would normally render him impure. The reason given was that a weasel or another animal in the well likely dragged the nefel into a side hole. Thus, the Kohen did not lean directly over the nefel. Here, we have a certainty that the nefel was in the pit, and a doubt whether an animal moved it. Yet, the rabbis were lenient, resolving a certainty with a doubt. This seems to contradict the earlier ruling regarding the nidah.
The Gemara responds by clarifying the case of the nefel: we do not know for sure that it was a nefel. The woman might have thrown in only the placenta or an empty sack. The Kohen merely went to see if it was male or female, implying an uncertainty about what was thrown in. Therefore, this is a "doubt within a doubt": a doubt whether a nefel was thrown in at all, and a further doubt about its gender if it was. This allows for leniency. The Gemara then suggests an alternative interpretation: it was a certainty that a nefel was in the pit, but also a certainty that an animal moved it. This would make it a "certainty within a certainty," again allowing for leniency. The Rashi clarifies that the Kohen was a wise man who wanted to issue a ruling on the woman's impurity, not merely out of curiosity. The Gemara ultimately concludes that the Kohen was not such a great sage if he would lean over a pit with a corpse, and that the final ruling came from other rabbis.
The discussion then shifts to a fundamental question in the laws of nidah: are fixed menstrual periods (vesetot) a Torah-level obligation (de'Oraita) or a rabbinic one (de'Rabbanan)? If they are de'Oraita, then if a woman misses checking herself at the time her period is due, we assume blood came out and she is impure, even if she checks later and finds herself clean. If they are de'Rabbanan, then if a subsequent check is clean, she is considered pure. This has significant practical implications. Rav states that if a woman has a fixed period, and the time for it came and went without her checking, but she later checked and found herself clean, she is pure. However, if she found blood, she must retroactively assume impurity from the time of the fixed period, and any ritually pure items she touched during that time become impure. This is referred to as choshesh shel veset (concern for the fixed period) and choshesh shel re'iyah (concern for the actual sighting). The Rashi explains that if the time of the fixed period precedes the actual sighting by more than 24 hours, she becomes impure retroactively from the fixed period. If it is less than 24 hours, she becomes impure retroactively for 24 hours from the sighting. The question is whether she would be impure retroactively even if she did not see blood, but merely missed the checking at the time of her fixed period.
The Gemara clarifies that Rav's ruling applies only if she actually saw blood later. If she checked later and found nothing, she is pure. This means Rav considers fixed periods to be a rabbinic obligation, so without actual blood, there is no impurity. Shmuel, however, disagrees, stating that even if she checked and found herself clean, she is still impure, because "the way of a woman is that her period comes at its appointed time" (orach b'zmano ba). This indicates a dispute between Rav and Shmuel regarding whether fixed periods are de'Oraita or de'Rabbanan. Rav holds they are de'Rabbanan, while Shmuel holds they are de'Oraita.
An alternative explanation for their dispute is offered: both Rav and Shmuel agree that fixed periods are de'Oraita. Their disagreement centers on the timing of the checking. Rav's leniency applies only if she checked herself immediately at the time of her fixed period and found nothing. In such a case, he assumes no blood came out. However, if she delayed her checking, like from Monday to Thursday, then Rav would agree she is impure, as blood could have come and been lost. Shmuel, on the other hand, is stringent even if she checked immediately, believing that a drop of blood could have come and been lost instantly. This interpretation suggests that everyone agrees fixed periods are de'Oraita, but they dispute the efficacy of an immediate checking.
Rav Nachman bar Yitzchak offers a third explanation: the dispute between Rav and Shmuel is precisely whether fixed periods are de'Oraita or de'Rabbanan. Rav holds they are de'Rabbanan, allowing leniency if no blood is found. Shmuel holds they are de'Oraita, requiring impurity even if no blood is found, based on the assumption that it came at its appointed time.
Rav Sheishet states that this dispute reflects an earlier disagreement among the Tannaim. Rabbi Eliezer says a woman who missed checking at her fixed period is impure (teme'ah nidah), even if she checks later and finds nothing. Rabbi Yehoshua says she should check, implying that if the check is clean, she is pure. This aligns with the de'Oraita vs. de'Rabbanan debate.
A Mishnah is then brought as support: if a woman was in a place of fear (e.g., due to robbers or war), and her fixed period arrived but she did not check, she is pure. This is because "fear removes blood" (haradah mesaleket et ha'damim). The implication is that if there were no fear, she would be impure for not checking, supporting the view that fixed periods are de'Oraita. However, the Gemara then cites a Baraita which states that if a woman sees blood from a wound (dam makah) in her womb, even if it coincides with her fixed period, she is pure. Rabban Gamliel says this applies even to a fixed period, while Rabbi Yehoshua argues that if it's a fixed period, it is nidah blood. This again highlights the dispute: is the fixed period a strong enough presumption to override the possibility of wound blood? This implies that Rabban Gamliel holds fixed periods are de'Rabbanan, while Rabbi Yehoshua holds they are de'Oraita.
The Gemara then introduces another dimension to the dispute: whether the womb (mekor) itself is a source of ritual impurity (makom tumah). Some hold that any blood passing through the mekor becomes impure, even if it originated from a wound and is not truly nidah blood. Rabban Gamliel says that a woman is pure from nidah impurity and permitted to her husband if the blood is from a wound, but the blood itself is impure because it passed through the mekor, making it a "father of impurity" (av tumah) and rendering her impure with a different type of impurity (tum'at erev). Rabbi counters, saying that if you are concerned about the fixed period, she should be impure for seven days as a nidah. If you are not concerned about the fixed period, then the mekor is pure, and she should be totally pure. This implies that Rabbi believes everyone holds fixed periods are de'Rabbanan, and the debate is solely about the status of the mekor. If the mekor is pure, then wound blood, even if it passes through, does not cause impurity.
The discussion shifts to a Mishnah concerning ritual checks before and after marital relations (tashmish) for women who eat ritually pure food (taharot). There is no requirement to check for tashmish itself if one does not eat taharot. Beit Shammai states that two cloths (eidei bedikah) are required for each act of tashmish: one before and one after. These are set aside and checked the next morning. If she has multiple acts of tashmish, she needs two cloths for each. Alternatively, if she only has one cloth, she should have tashmish by candlelight (le'or ha'ner) so she can check the cloth immediately after each act. Beit Hillel, however, says that two cloths suffice for the entire night: one before the first tashmish and one after the last. The Rashi explains that Beit Shammai wants to know precisely when impurity occurred, perhaps even for bringing a sacrifice. Beit Hillel believes that knowing the overall status by morning is sufficient. Both agree that the primary concern is for taharot, not for tashmish itself, as one can continue tashmish even without immediate knowledge of impurity. The dispute is over the number of checks and whether a separate cloth is needed for each.
The Gemara challenges Beit Hillel: why do they not suspect that a small drop of blood might come out after the first tashmish, which would then be covered and diluted by the seminal fluid (zerah) of subsequent acts, making it undetectable? Beit Hillel responds that Beit Shammai faces the same problem, as even after a single act of tashmish, seminal fluid could dilute any blood. The difference is that Beit Shammai's concern is limited to one act, while Beit Hillel's approach could lead to dilution after multiple acts. Rabbi Yehoshua suggests that a pious person (ba'al nefesh) should be stringent and not engage in a second act of tashmish without checking, even though the law (halakha) follows Beit Hillel. This stringency is for the sake of a longer life in the World to Come. The Gemara clarifies that this stringency applies to those who are particular about taharot, not to ordinary people, for whom there is no concern about seeing blood during tashmish for the purpose of tashmish itself, only for taharot.
A further discussion arises regarding a woman who performed a checking before tashmish but then lost the cloth. Rabbi says she must perform another checking, implying that the cloth serves as proof. If she loses it, the proof is gone. The Sages (Chachamim) disagree, stating that if she does not have it, she does not need to check again. Even if she had it, she would not check it until the next morning, so losing it does not change the immediate permissibility of tashmish. The Gemara explains that the Sages mean that the purpose of the cloth is for later verification regarding taharot and potentially a sacrifice (korban) for nidah. If the cloth is lost, this purpose is defeated, hence the need for another check. However, it is not a concern for the permissibility of tashmish itself.
The Gemara then discusses why tashmish should not occur during the day. This is derived from a verse in Job: "Day by day, they are hidden, but at night, a man conceives" (Yom al-yom ye'ivaled bo, ve'laylah amar hora gever). This verse implies that night is designated for conception. Reish Lakish offers another reason: "He who goes in his way will die" (Bozeh derachav yamut). This is interpreted to mean that one who engages in tashmish in a disrespectful manner, such as during the day, where he might see something unappealing about his wife and be disgusted, will die. At night, he cannot see her, thus avoiding such negative thoughts. This is a rabbinic decree (de'Rabbanan) supported by these verses, not a Torah-level prohibition.
The Gemara then explores how each sage interprets the verses used by the other. Rabbi Yochanan, who cited the verse from Job, explains that "night" (laylah) refers to an angel named Laila who is in charge of conception. This angel tastes a drop of seminal fluid and determines the child's attributes: strong or weak, wise or foolish, rich or poor. However, whether the child will be righteous or wicked is not predetermined, as that depends on free will. This is encapsulated in the saying, "Everything is in the hands of Heaven except for the fear of Heaven." The verse, by associating "night" with "conception," alludes to this angel. Rabbi Hanan challenges this, saying if this was the sole teaching, the verse would have simply stated "Laila conceives." The phrasing "at night, a man conceives" suggests a direct connection between night and conception, which is the primary teaching.
Conversely, Rabbi Yochanan asks what Reish Lakish does with the verse from Proverbs, "He who goes in his way will die." Rabbi Yochanan explains that this verse refers to the sayings of Ben Sira, son of Jeremiah, who listed three people he hated and a fourth he disliked. These include a Torah scholar who frequents parties, one who talks excessively, one who acts like a drunkard (is always angry), one who sits in a high place to teach (out of arrogance), one who holds onto the privy when relieving himself (implying lack of modesty), and one who enters his friend's house unannounced. Even in one's own house, one should announce their presence to allow family members to dress appropriately, preventing embarrassment. This illustrates the concept of "disrespectful ways" (derech bizayon) that Reish Lakish's verse alludes to, emphasizing modesty and respect in all actions, including marital relations.