(R. Yochanan citing R. Yannai): This is one of three clear pesukim expounded about Terumah - the pasuk states (Devarim 26:3), "And he shall come to the Kohen that will be in those days''. Is there someone who is a Kohen now but will not be a Kohen later? It's referring to one who is sacrificing on the altar and who is informed that he is the son of a divorcee or of one who performed Chalitzah (a Chalutzah) - his service is valid.

(Rav): The pasuk states (Devarim 33:11), "and favorably accept the work of his hands'' - whoever is a descendent of Levi, his service is valid (if it was mistakenly done by one who is disqualified).

According to Rav, it's as long as it was done by a Kohen who was serving (thinking that he was permitted to do so). According to R. Yochanan, it applies to any Mitzvah that requires a Kohen (for example, making a ruling if someone has Tzora'as (leprosy)).

According to Rav, the pasuk applies to offering sacrifices. According to R. Yochanan, it applies even to other laws (such as our Mishnah's case of a Kohen who ate Terumah and then discovered that he was disqualified from eating).

According to Rav, it only applies in Temple times. According to R. Yochanan, it even applies nowadays.

Question (R.Yirmiyah): Does R. Yehoshua permit other acts after the fact as well? For example, if a Kohen received the blood of a sacrifice and then discovered that he was disqualified, can that blood be thrown? If he took the handful of incense and then discovered that he was disqualified, can that incense be burned? If he burned the Parah Adumah (Red Heifer) and then discovered that he was disqualified, can those ashes be used to sprinkle on a Tamei person?

Answer (R. Yaakov bar Zavdi): From the Baraisa's teaching, that when a Kohen discovered that he was disqualified, they viewed it like a stolen Chatas offering that was not known to the public and it achieves atonement; this shows that all of those acts are permitted after the fact.

Question (R. Yaakov bar Zavdi citing R. Yitzchak): (The Mishnah in Maseches Makos teaches that if an inadvertent killer's verdict of exile occurred when there was no Kohen Gadol, he can never leave the City of Refuge.) If the Kohen Gadol was standing and sacrificing on the altar and he discovered that he was the son of a divorcee or a Chalutzah, what's the law? Is it as if he died now and the killer can go free; or is it as if the killer's verdict was at a time when there was no Kohen Gadol and he can never leave?

Answer (Tosefta): There was a case of Diski's pool in Yavneh, when some of the water came out and it was measured and was less than 40 Se'ah. R. Tarfon ruled that anything immersed in it beforehand was Tahor (as it could be assumed that the water came out now). R. Akiva rueld that they are Tamei.

(R. Tarfon): The Mikveh is assumed to have always been Tahor until it was known that it was incomplete.

(R. Akiva): The item that was immersed is assumed to have been Tamei until it was known that it was correctly immersed.

(R. Tarfon): It's comparable to one who was standing and sacrificing on the altar and it was discovered that he was the son of a divorcee or a Chalutzah, that his service is valid.

(R. Akiva): It's comparable to one who was standing on the altar and he was informed that he is a Ba'al Mum (he had a defect that renders him disqualified to serve), that his service is invalid.

(R. Tarfon to R. Akiva): I compare it to the son of a divorcee and you compare it to a Ba'al Mum. To who is it correct to compare?

(R. Akiva to R. Tarfon): A Mikveh is itself invalid and so is a Ba'al Mum, as opposed to the son of a divorcee whose disqualification comes from others. A Mikveh becomes invalid through one witness and so does a Ba'al Mum, as opposed to the son of a divorcee, who is only disqualified through a decision of Beis Din.

(R. Tarfon to R. Akiva): One who separates from you is like separating from life.

(R. Yosi): This shows that if a Kohen was standing and serving on the altar and it was discovered that he was the son of a divorcee or a Chalutzah, his service is valid until he is disqualified by Beis Din.

The Baraisa also shows that if a Kohen served on the altar and then discovered that he had a doubtful Tumah or he was a doubtful Ba'al Mum, even according to R. Tarfon, his service is invalid. The reason that R. Tarfon permitted it in the case of the Mikveh was because it was compared to a Kohen who was found to be the son of a divorcee; but had he compared it to a Ba'al Mum, even the Mikveh would have been invalid. It was doubtful if the Mikveh was lacking and if you say that a doubtful Ba'al Mum's service is valid, you would need to say the same for the Mikveh.

(R. Chanina): The Baraisa also shows that a disqualification due to lineage requires Beis Din to rule on it.

(R. Yochanan): R. Eliezer and R. Yehoshua disagree over a slave and a woman (who began eating Terumah with permission. R. Yehoshua says there that since they began with permission, they may swallow it.) But for other things, such as when he was informed that he was a Chalal, even R. Eliezer agrees that he must spit it out (as the disqualification is retroactive).

(R. Shmuel bar Rav Yitzchak): Our Mishnah also teaches this (Chulin 93-2(e)), as it says, "or he was informed that it was Tevel, Maaser Rishon that had not had its Terumah taken or Maaser Sheni or Hekdesh that had not been redeemed (or if he tasted the taste of a flea in his mouth, he should spit it out.) And R. Eliezer doesn't disagree there - he only permits in the case of the slave and the woman because they had started eating when it was permitted (but here it was prohibited).

Baraisa (R. Nasan): That's not his reasoning - rather it's because when one chews on food, it's as if he has already swallowed it.

The same is true for Shabbos (that if a person went out into the public domain chewing food, he has not transgressed as it's considered to have already been swallowed) and for Pesach (if he entered into Pesach with chewed Chametz in his mouth) and for Yom Kippur and for a Nazir (with chewed grapes in his mouth) and for Neveilos and for Treifos and for creeping things and for insects.

(R. Chiya citing R. Yochanan): If one slaughters an animal and finds a creeping thing in (its lung), it may not be eaten. Why? The pasuk states (Devarim 14:6), "And every animal... among (lit. in) the animals that you may eat'' - but not a creeping thing in the animal.

Question (R. Yona in the name of R. Hoshiya): How is it different to fleas found inside lentils, fleas in Kelisin beans and worms in dates and figs, that as long as they didn't separate from the food and move on the ground (as the Torah describes them as things that creep on the ground), one would not be liable for eating them?

Answer: There, as long as they haven't separated, they are considered part of the lentil, but a creeping thing inside an animal doesn't grow inside the animal.

A flea that grows inside fish brine (that contains fish blood) before it was filtered, (its blood is not viewed as a separate entity and) it is permitted; after it has been filtered, it is prohibited.

Tosefta: Blood (from one's gums) that is on a loaf of bread, he should scrape it off and he may eat it. Blood that is still between his teeth is permitted to swallow without concern.

The pasuk states (Vayikra 11:41), "(And any creeping thing that creeps on the ground) is an abomination; (it shall not be eaten)'' - this includes Shavzizin, Bazizin and Bahgazin (which are different types of fleas).

I might have thought that they are prohibited whilst still in the fruit, but the next pasuk states, "they are an abomination'', which teaches that they are only prohibited when they are separate entities, but not whilst still in the fruit.

I might have thought that even if they left and then returned to the fruit, they are not prohibited; the pasuk states, "it's an abomination''- even if they left and returned, they remain prohibited.

(R. Chiya bar Ashi citing Rav): Even if they went out to the edge of the food and then returned, they are prohibited.

(Abba bar Rav Huna citing R. Yochanan): One who slaughters an animal and finds something with the appearance of a Chazir (pig) inside it, it may be eaten. If it's the appearance of a dove, it is prohibited.

Why? The pasuk states "an animal...in an animal you may eat'' but not a bird or creeping thing in an animal.

(The Mishnah taught (Chulin 93-2(e)) that if a person discovered a flea in his mouth whilst eating Terumah, he may spit the Terumah out, even though it will be wasted). This applies not only a flea but to anything that a person is disgusted by.