1) FEELING THE BLOOD EXIT THE BODY
QUESTION: The Gemara (57b) quotes Shmuel who says that when a woman checked the ground beneath her and found it to be clean, and then she sat on it and found blood there, she remains Tahor, because the Torah says that a woman is Tamei only when blood flows from a woman "bi'Vesarah" -- "in her flesh" (Vayikra 15:19). This verse teaches that she is Tamei only when she feels a Hargashah, sensation, of blood leaving her body.
The Gemara challenges Shmuel's statement from several Mishnayos and Beraisos which imply that a woman is Tamei even when she had no Hargashah. The Gemara concludes by quoting Rav Ashi who answers that Shmuel follows the view of Rebbi Nechemyah. The Mishnah later (59b) quotes Rebbi Nechemyah who says that if a Kesem is found on an object that cannot become Tamei (such as the ground), the woman does not become Tamei as a result of that Kesem.
(TOSFOS here (DH k'Rebbi) points out that Rebbi Nechemyah's reasoning is that since the Tum'ah of a Kesem is only mid'Rabanan (since, mid'Oraisa, she is Tahor, because she did not feel the blood exit her body), the Rabanan did not enact a Gezeirah to make the woman Tamei when the Kesem is found on something that cannot become Tamei.)
RASHI (DH Rav Ashi) writes that Shmuel's reason for saying that she is Tahor is not that she did not have a Hargashah, but rather Shmuel agrees with Rebbi Nechemyah, and therefore all of the questions asked on Shmuel are not difficult because Shmuel is not discussing Hargashah at all.
What does Rashi mean when he says that Shmuel's reason is unrelated to Hargashah? The Gemara says explicitly that Shmuel's reason is that there was no Hargashah!
ANSWER: The SIDREI TAHARAH (YD 190:93) writes that it is not reasonable to answer that Rashi understands that the words, "until she feels in her flesh," are not part of Shmuel's statement but are the words of the Gemara explaining Shmuel's ruling.
The Sidrei Taharah explains instead that Rav Ashi understands, according to Shmuel, that the reason why a Hargashah is required in order for a woman to become Tamei mid'Oraisa is that if she does not feel the blood exit her body, there is a doubt that perhaps the stain she found did not come from her body. Even if she checked the ground before she sat on it and did not find blood there, we do not assume beyond a doubt that blood that she finds there afterwards came from her. Rather, it remains a doubt. Perhaps the blood was there before she sat down, and she merely failed to check thoroughly. However, mid'Rabanan she is Tamei even without a Hargashah. The Rabanan did not apply their Gezeirah when the item on which the stain was found is not Mekabel Tum'ah.
The Sidrei Taharah cites proof for this approach from the words of Rashi later (62b, DH Amar Lei). Rashi writes that "the basis of the Gezeirah of Kesamim is only mid'Rabanan. Therefore, in certain cases we are lenient, because mid'Oraisa she is not Tamei until she sees the blood in her flesh." Rashi intentionally writes "until she sees" the blood in her flesh rather than "until she feels" the blood. According to Rav Ashi (whose opinion is the conclusion of the Gemara), a woman's Tum'ah does not depend on having a Hargashah, but on whether the blood definitely came from the woman. If it definitely came from her, she is Tamei mid'Oraisa even if she felt nothing. Although a Hargashah usually proves that the blood came from her, blood can come from her even without a Hargashah. The Sidrei Taharah points out that her Tum'ah does not even depend on her "seeing" blood, as Rashi writes; even if she did not see blood but knows for certain that the blood is from her, she is Tamei mid'Oraisa, without a Hargashah and without "seeing." (The Sidrei Taharah adds that this explanation is also apparent from the words of Rashi earlier on 53b, DH Mahu, and 54b, DH v'Hu.)
The CHAVOS DA'AS (190:4) proves this principle from the Gemara earlier (5a) which says that a Ketanah who is not old enough to have Dam Nidah is Tahor even if she finds her sheets soiled with blood. Rashi there (DH Meluchlachin) writes that the case is when she does not know whether the blood came from her. Rashi (DH Ein Chosheshin) writes that even if she has no explanation for the source of the blood (for example, she did not pass through a marketplace of slaughtered animals), we still assume that she may have walked through such a place and does not remember. The Chavos Da'as comments that it is clear that if we would be certain that the blood came from her, she would be a Nidah even if she did not feel the blood leave her body. (D. BLOOM)
2) "KESAMIM" NOWADAYS
QUESTION: The Mishnah teaches that when a woman finds a Kesem (bloodstain) on her sheet, she may attribute it ("Tolah") to a bug that she killed and not to a flow of Dam Nidah. The Gemara infers that the Mishnah follows the view of Raban Shimon ben Gamliel, who says that she may attribute the Kesem to a dead bug only when she killed one. The Chachamim say that she may attribute it to a dead bug whether or not she killed one. Raban Shimon ben Gamliel comments about his own ruling that it is very stringent. All beds have some drops of blood on them from lice, and when the woman finds blood she will not be able to be Tolah the blood on a bug that she killed unless she knows that she indeed killed one.
The RA'AVAD (in BA'ALEI HA'NEFESH, introduction to Sha'ar ha'Kesamim) asks a strong question from this Gemara on the opinion of his grandfather-in-law, RABEINU AVRAHAM AV BEIS DIN. Rabeinu Avraham rules that the laws of Kesamim do not apply today, since the laws of Kesamim apply only with regard to Taharos; a woman who finds a Kesem on her sheet or garment may not handle Taharos, but she may be with her husband unless she experiences actual bleeding. Since women no longer handle Taharos, the laws of Kesamim are not relevant.
The Ra'avad disproves the opinion of Rabeinu Avraham Av Beis Din from the words of Raban Shimon ben Gamliel. Raban Shimon ben Gamliel specifically discusses whether a woman is permitted to be with her husband, and not merely whether she may handle Taharos. Why, then, does Rabeinu Avraham Av Beis Din say that the laws of Kesamim do not apply today?
ANSWER: The ARUCH LA'NER and CHASAM SOFER (58a) answer this question based on the Gemara earlier (11b). The Gemara says that although the requirement to perform a Bedikah in the morning and in the evening was instituted in order to protect Taharos from becoming Tamei, a woman who has no fixed Veses and always handles Taharos is also required to do a Bedikah in order to be permitted to her husband. Similarly, according to Rabeinu Avraham Av Beis Din, a woman who always handles Taharos needs to consider herself Tamei when she finds a Kesem. Perhaps Rabeinu Avraham agrees that such a woman needs to consider herself Tamei for her husband as well. However, nowadays a woman does not handle Taharos, and therefore Kesamim also do not cause Tum'ah with regard to her husband.
This explanation is consistent with the words of Rabeinu Avraham Av Beis Din. He writes that Kesamim do not apply "today," and not that they apply "only to Taharos," as the Ra'avad and other Rishonim seem to understand. When the laws of Taharos are in effect, the laws of Kesamim apply to marital relations as well.
Most Rishonim disagree with the opinion of Rabeinu Avraham Av Beis Din. The Poskim rule that the laws of Kesamim apply today with regard to prohibiting a woman to her husband.