Both this one and that one, i.e., items of both forms of impurity, impart impurity until they are no longer fit to be eaten by a dog, it poses a difficulty to the opinion of Rabbi Yirmeya, as this mass is fit for a dog. The Gemara concludes: Indeed, it is difficult.

The Gemara discusses the matter itself. Bar Padda says: An item with severe ritual impurity imparts impurity to substances until it is no longer fit to be eaten by a ger toshav, but an item with light impurity imparts impurity to substances until it is no longer fit to be eaten by a dog. And Rabbi Yoḥanan says: Both this one and that one impart impurity until they are no longer fit to be eaten by a dog. The Gemara asks: What is the reason for the ruling of bar Padda? As it is written: “You shall not eat of any animal carcass; you may give it to the ger who is within your gates” (Deuteronomy 14:21). Bar Padda understands from this verse that an item which is fit for a ger toshav is called an animal carcass, and that which is not fit for a ger toshav is not called an animal carcass.

The Gemara asks: And with regard to the other Sage, Rabbi Yoḥanan, how does he interpret that verse? He maintains that it serves to exclude a carcass that was decayed from the outset, e.g., if the flesh started to decompose while the animal was still alive, due to severe injury. But if the carcass was initially edible and later decayed, it continues to impart ritual impurity provided it is fit for a dog. The Gemara asks: And with regard to the other Sage, bar Padda, how does he respond to this claim? A verse is not necessary to exclude such a case where the carcass was decayed from the outset, as it is merely like dust and obviously does not impart impurity.

We learned in our mishna that Rabbi Eliezer ben Ya’akov says: In the case of a large animal that expelled a mass of congealed blood, that mass must be buried, and the animal is exempt from having any future offspring counted a firstborn. And Rabbi Ḥiyya teaches: That mass of congealed blood does not impart ritual impurity, neither through physical contact nor through carrying. And Rabbi Yoḥanan says: It is due to the halakhic nullification of a forbidden substance in a majority of permitted substances that the Sages touched upon it, in order to exclude it from impurity through contact or carrying.

The Gemara asks: Why did Rabbi Yoḥanan say this halakha is due specifically to the nullification of a substance in a mixture by the majority of the mixture? Let one derive the halakha from the fact that the mass is not fit for consumption at all, and it never was. The Gemara explains: This too was initially fit by virtue of its mother, i.e., if one had slaughtered the mother before the embryo was discharged it would have been edible as part of the mother.

We learned in a mishna elsewhere (Makhshirin 6:3) that Rabbi Eliezer ben Yaakov says: Ritually pure brine, taken from an am ha’aretz, into which any amount of water fell is rendered impure. Rav Naḥman says that Rabba bar Avuh says: That is to say that amei ha’aretz are suspected of mixing half a portion of water in the brine, which means that when the additional water falls in, the nullified impurity in the brine is revived by it and renders the entire mixture impure. The Gemara asks: But why do I need to say they are suspected of mixing precisely half a portion of water? Even if they mix in less than half, the brine will also be rendered impure upon contact with the added water, as that small amount combined with slightly less than half a portion of water constitutes half the mixture, and half a mixture is not nullified by the other half.

The Gemara answers: Say instead that an am ha’aretz is suspected of mixing in water until it constitutes slightly less than half the mixture. And if you wish, say instead: The impurity of foods belonging to an am ha’aretz applies by rabbinic law and the impurity of liquids also applies by rabbinic law. Accordingly, the impurity of the brine in this case is due to two separate rabbinic decrees. Where the majority is water the Sages decreed the brine is impure, but in a case where half the mixture is pure fish brine and half is water the Sages did not decree that the brine is impure.

MISHNA: Rabban Shimon ben Gamliel says: In the case of one who purchases a nursing female animal from a gentile, he does not need to be concerned, i.e., take into account the possibility, that perhaps it was nursing the offspring of another animal. Rather, the buyer may assume it had previously given birth. In the case of one who enters amid his flock and sees mother animals that gave birth for the first time that were nursing, and also sees mother animals that gave birth not for the first time that were also nursing, he does not need to be concerned that perhaps the offspring of this animal came to that animal to be nursed, or that perhaps the offspring of that animal came to this animal to be nursed.

GEMARA: Rav Naḥman said in the name of Rav: The halakha is in accordance with the opinion of the anonymous tanna in the mishnayot throughout the whole chapter, except where there is a difference of opinion recorded in that mishna. Rav Sheshet says: I say Rav was dozing or sleeping when he said this halakha. After all, to which mishna is this referring? If we say it is referring to the first mishna in the chapter (19b) then his ruling does not apply, as Rabbi Yishmael and Rabbi Akiva disagree in that mishna.

Rather, you will say it is referring to the ruling of Rabbi Eliezer ben Yaakov (21b). This is also problematic, since it is already known that the halakha is in accordance with his opinion, as there is an established principle that the teaching of Rabbi Eliezer ben Ya’akov measures only a kav but is clean and accurate, and therefore the halakha is in accordance with his opinions.

Rather, you will say it is referring to the statement of Rabban Shimon ben Gamliel in the mishna here. That is also difficult, as there is a tanna who disagrees, in the baraita cited on 24a. Rather, you will say that it is referring to the statement of Rabbi Yosei ben HaMeshullam in the next mishna (24b). But didn’t Rav already say this one time? As Rav said: The halakha is in accordance with the opinion of Rabbi Yosei ben HaMeshullam. Rather, you will say that it is referring to the matter of the hair of a blemished firstborn discussed in the mishna on 25b. But that case too is subject to a dispute, as Akavya ben Mahalalel and the Rabbis disagree in that mishna.

The Gemara answers: Actually, Rav’s statement is referring to the statement of Rabban Shimon ben Gamliel here, and Rav teaches us this: That if a mishna is contradicted by a dissenting opinion cited in a baraita it is not considered a dispute, and the halakha therefore follows the opinion of Rabban Shimon ben Gamliel.

The Gemara asks: But once Rav said the halakha is in accordance with the opinion of the anonymous tanna in the mishnayot throughout the whole chapter except where there is a difference of opinion,