Rabbi Yishmael, son of Rabbi Yosei, explained: It is only Rabbi Ḥanina who is permitted to examine the blood in this fashion, as he is wise, but everyone else is not so wise that they can successfully perform the examination without water.

Rabbi Yoḥanan says: Rabbi Ḥanina’s wisdom causes me not to see blood for a halakhic examination. When I would examine blood and deem it impure, he would deem it pure, and when I would deem it pure, he would deem it impure. Conversely, Rabbi Elazar says: Rabbi Ḥanina’s humility causes me to see blood, as I reason to myself: If Rabbi Ḥanina, who is humble, places himself into a situation of uncertainty and sees various types of blood to determine their status, should I, who am not nearly as humble, not see blood for an examination?

Rabbi Zeira says: The complex nature of the residents of Babylonia causes me not to see blood for a halakhic examination, as I say to myself: Even matters involving the complex nature of people I do not know; can I then claim that I know about matters of blood?

The Gemara asks: Is this to say that the matter of the appearance of blood is dependent on the nature of people, i.e., that it changes in accordance with their nature? But Rabba is an example of someone who knew about the complex nature of the people of Babylonia, and yet he did not know how to distinguish between different types of blood. The Gemara answers: Rabbi Zeira took this factor into account and said to himself: All the more so; if Rabba, who knew about the complex nature of these people, nevertheless would not see blood, should I, who am unknowledgeable about the nature of these people, see blood for examination?

The Gemara relates that Ulla happened to come to Pumbedita, where they brought blood before him for an examination, but he would not see it, as he said: If Rabbi Elazar, who was the master of Eretz Yisrael in wisdom, when he would happen to come to the locale of Rabbi Yehuda, he would not see blood, shall I see blood here?

The Gemara asks: And why would they call Rabbi Elazar the master of Eretz Yisrael in wisdom? The Gemara explains that there was an incident involving a certain woman who brought blood before Rabbi Elazar for examination, and Rabbi Ami was sitting before him. Rabbi Ami observed that Rabbi Elazar smelled the blood and said to the woman: This is blood of desire, i.e., your desire for your husband caused you to emit this blood, and it is not the blood of menstruation. After the woman left Rabbi Elazar’s presence, Rabbi Ami caught up with her and inquired into the circumstances of her case. She said to him: My husband was absent on a journey, and I desired him. Rabbi Ami read the following verse about Rabbi Elazar: “The counsel of the Lord is with those who fear Him; and His covenant, to make them know it” (Psalms 25:14), i.e., God reveals secret matters to those who fear Him.

The Gemara further relates that Ifera Hurmiz, the mother of King Shapur, sent blood before Rava for examination, as she sought to convert and was practicing the halakhot of menstruation. At that time Rav Ovadya was sitting before Rava. Rav Ovadya observed that Rava smelled the blood and later said to the woman: This is blood of desire. She said to her son: Come and see how wise the Jews are, as Rava is correct. Her son said to her: Perhaps Rava was like a blind man who escapes from a chimney, i.e., it was a lucky guess.

Ifera Hurmiz then sent Rava sixty different types of blood, some impure and others pure, and with regard to all of them Rava accurately told her their origin. The Gemara adds: That last sample of blood sent by Ifera Hurmiz was blood of lice, and Rava did not know what it was. He received support in this matter in the form of heavenly guidance, as he unwittingly sent her as a gift a comb for killing lice. She said in exclamation: Jews, you must dwell in the chamber of people’s hearts.

§ The Gemara cites more statements of the Sages with regard to the examination of blood. Rav Yehuda says: At first I would see blood, i.e., perform examinations of blood, but I changed my conduct when the mother of my son Yitzḥak, i.e., my wife, said to me that she acts as follows: With regard to this first drop of blood that I see, I do not bring it before the Sages, because it is not pristine blood, i.e., other substances are mixed with it. After hearing this, I decided I would no longer see blood, as it is possible that the first drop, which I do not get to see, was impure.

Rav Yehuda continues: But with regard to the examination of blood that a woman who gave birth emitted after the completion of her days of purity, i.e., at least forty days after giving birth to a male, or eighty after giving birth to a female (see Leviticus, chapter 12), in order to determine whether she is ritually impure or pure, I certainly see this blood and determine her status based on its color. This blood is clean, as the woman has been bleeding for a long period of time.

§ The Gemara relates that Yalta, Rav Naḥman’s wife, brought blood before Rabba bar bar Ḥana, and he deemed her ritually impure. She then brought it before Rav Yitzḥak, son of Rav Yehuda, and he deemed her pure.

The Gemara asks: But how could Rav Yitzḥak, son of Rav Yehuda, act in this manner? But isn’t it taught in a baraita: In the case of a halakhic authority who deemed an item impure, another halakhic authority is not allowed to deem it pure; if one halakhic authority deemed a matter prohibited, another halakhic authority is not allowed to deem it permitted?

The Gemara explains that initially Rav Yitzḥak, son of Rav Yehuda, deemed her impure, but he changed his mind when Yalta said to him: Every day that I bring blood of this kind of color to Rabba bar bar Ḥana he deems me pure, and specifically now he issued a different ruling, as he feels pain in his eye. Upon hearing this, Rav Yitzḥak, son of Rav Yehuda, deemed her pure.

The Gemara asks: But are people deemed credible to present claims such as the one presented by Yalta? The Gemara answers: Yes; and likewise it is taught in a baraita: A woman is deemed credible if she says: I saw blood like this color, but I lost it before it could be examined.

A dilemma was raised before the Sages: If a woman states to her friend who showed her blood: My blood, which has an appearance like this, so-and-so, the halakhic authority, deemed it pure, what is the halakha? Is she deemed credible concerning its status?

The Gemara suggests: Come and hear a resolution to this dilemma from the baraita cited above: A woman is deemed credible if she says: I saw blood like this color, but I lost it. This demonstrates that a woman may issue claims of this kind. The Gemara rejects this proof: There it is different, as in that case the blood is not before her, and therefore the Sages were lenient. But here, the woman’s friend can take her blood to a halakhic authority for examination.

The Gemara further suggests: Come and hear the incident cited above, as Yalta brought blood before Rabba bar bar Ḥana, and he deemed her ritually impure; she then brought it before Rav Yitzḥak, son of Rav Yehuda, and he deemed her pure. And the Gemara asked: How could Rav Yitzḥak, son of Rav Yehuda, act in this manner? But isn’t it taught in a baraita: In the case of a halakhic authority who deemed an item impure, another halakhic authority is not allowed to deem it pure?

And we say in response that initially Rav Yitzḥak, son of Rav Yehuda, deemed her impure, but he changed his mind when she said to him that every day that she brings blood of this kind of color to Rabba bar bar Ḥana he deems her pure, and specifically now he issued a different ruling, as he feels pain in his eye. The Gemara summarizes: The conclusion of the story was that upon hearing this, Rav Yitzḥak, son of Rav Yehuda, then deemed her pure. Evidently, when a woman issues claims with regard to blood that is presented, we deem her claims credible.

The Gemara answers: That incident does not provide proof, as Rav Yitzḥak, son of Rav Yehuda, relied on his studies in his lenient ruling. At first, he was reluctant to issue his ruling, in deference to Rabba bar bar Ḥana, who had said the blood was impure. But when he heard Yalta’s explanation he deemed the blood pure, as he had originally thought. Therefore, there is no proof from there that a woman’s statements of this kind are accepted.

§ The Gemara further relates: Rabbi Yehuda HaNasi once saw a woman’s blood at night and deemed it impure. He again saw that blood in the day, after it had dried, and deemed it pure. He waited one hour and then deemed it impure again. It is assumed that Rabbi Yehuda HaNasi did not conduct another examination at this point; rather, he reasoned that the previous night’s examination had been correct, and the blood’s color should be deemed impure because of how it had looked when it was moist. Rabbi Yehuda HaNasi then said: Woe is me! Perhaps I erred by declaring the blood impure, as based on its color it should be pure.

The Gemara questions this statement: Perhaps I erred? He certainly erred, as it is taught in a baraita that a halakhic authority may not say: If the blood were moist it would certainly have been impure, and yet here, Rabbi Yehuda HaNasi deemed the blood impure based on that type of reasoning.

The Gemara explains that the incident did not unfold as initially assumed. Rather, Rabbi Yehuda HaNasi examined the blood three times, as he said: A judge has only what his eyes see as the basis for his ruling. Initially, Rabbi Yehuda HaNasi established the presumptive status of the blood as ritually impure, but when he saw in the morning that its color had changed, he said: It was definitely pure last night as well, and only because it was at night I thought that it was impure, because it could not be seen well. Subsequently, when he saw after a short while that its color again changed, Rabbi Yehuda HaNasi said: This blood is impure, and it is gradually becoming lighter as its color fades.

With regard to the manner in which the Sages would examine blood, the Gemara relates that Rabbi Yehuda HaNasi would examine blood by candlelight. Rabbi Yishmael, son of Rabbi Yosef, would examine blood between the pillars of the study hall even on a cloudy day, despite the fact that it was not very light there. Rav Ami bar Shmuel says: And in all these cases, one examines blood only between sunlight and shade. Rav Naḥman says that Rabba bar Avuh says: One stands in a place lit by the sun, and he conducts the examination under the shadow of his hand, i.e., he places his hand over the blood. In this manner the color of the blood can be best discerned.

§ The mishna states: And what is the color that is like diluted wine that is impure? It is specifically when the dilution consists of two parts water and one part wine, and specifically when it is from the wine of the Sharon region in Eretz Yisrael. The Sages taught in a baraita: