Explanation: This is correct before he pays. However, after he pays, it becomes Terumah (that is impure) and he cannot eat it at all. (Note: Rashi (DH "v'ka'Meshalem") explains that the Gemara's point is that at least he had good intent to pay him with something that was more useful than what he ate.)

Opinion: This is unlike Rashi's explanation that he pays according to the measurement (not the value).

Implied Question: Even if you will say that he pays according to the measurement, he will not be exempt unless he will pay their value for burning which will equal the amount of pure Terumah that he ate. This is because he is not worse than a thief.

This is as stated there (Pesachim 32a) that whenever it was worth four Zuz and in the end it was worth a Zuz, it is clear that he pays according to the value. The question is only when originally it was worth a Zuz and then became worth four Zuz. In any event, if he did so on purpose his payment is not valid. This is because he ate something that people buy quickly and paid back something that people do not buy quickly. (Note: Tosfos' point is that unlike Rashi who seems to use paying according to measurement as a leniency, it is actually a stringency. This is evident from the question in the Gemara in Pesachim (ibid.).)

Explanation: In Yevamos (90a), the Gemara originally thinks that Rebbi Meir must mean that the payment is totally invalid. The Gemara therefore asks that the Chachamim do not have the ability to uproot something from Torah law. (Note: As according to Torah law the payment is valid.)

The Gemara concludes that Rebbi Meir means that his payment is not considered payment (though it belongs to the Kohen), and therefore he must go back and pay pure Chulin, as stated by the Rabbanan (that his payment is a payment, yet he must pay again). The Rabbanan and Rebbi Meir only argue whether or not we fine someone who does so accidentally because of someone who pays on purpose (with impure Chulin).

Question: What is difficult according to Rebbi Meir? This is not a general Mishnah (which is supposed to be according to Rebbi Meir), but rather a Beraisa in Menachos (25a)!

Answer: The Gemara relies on the general Mishnah in Pesachim (80b). The Mishnah there states that if the blood of a Korban Pesach was sprinkled and afterwards it became known that it was impure, the Tzitz atones. The Gemara deduces that the reason it atones is that it became known after the sprinkling. If it was known that it was impure and afterwards the blood was sprinkled, the Tzitz would not atone.

The Gemara quotes a Beraisa that explains this clearly. This question is on Ravina, who explains there that the accidental aspect of the case is that it was sprinkled. (Note: This is the same as our Beraisa that has a case of sprinkling accidentally, and is why the Gemara can ask its question.) According to Rav Shilo who explains that it accidentally became impure there is no question, as impurity is a Torah concept. (Note: See the Gemara in Pesachim ibid. at length.)

Explanation: This is a Mishnah in Terumos (2:3), as is the Mishnah regarding one who immerses vessels (quoted in our Gemara). The Gemara asks questions from these Mishnayos because general Mishnayos are based on the opinion of Rebbi Meir.

Question: This is difficult. The Gemara asks first from Ma'aser, even though it is stated later (in the very same Mishnah after the case of the immersed vessels). (Note: Why didn't it first ask from immersing vessels, which is the first case of the Mishnah?)

Question: This is difficult. The Yerushalmi in the last chapter of Orlah quotes a braisa that states the following. If they (expensive nuts of Orlah) fell (into nuts that were permitted to eat) and were afterwards smashed (and there was enough permitted nuts to technically permit the mixture), whether this happened accidentally or on purpose, they should not be ruled permitted. These are the words of Rebbi Meir. Rebbi Yehudah says that whether this happened accidentally or on purpose, they can be ruled permitted. Rebbi Yosi says that if this happened accidentally they can be ruled permitted, but if this happened on purpose they should not.

Rebbi Meir's reasoning is that he says that a fine should be applied to accidental circumstances, lest people do so on purpose. Rebbi Yosi's reasoning is as stated by Rebbi Avahu in the name of Rebbi Yochanan. He says that any forbidden things that now have more permitted items mixed with them (in order that the forbidden part can be nullified and the mixture ruled permitted) are indeed permitted if they were mixed accidentally, but not if they were mixed on purpose. Rebbi Yehudah's reasoning is "that his fine is already in his hand." This means that his fruit already became ruined when the nut was smashed. (Note: The question is that the Yerushalmi's version is clearly different than the version quoted in our Gemara.)

Question: Rabeinu Tam asks that here, even according to Rava he is only believed because it was originally in his hands.

In Kidushin (66a), Abaye and Rava argue regarding a case where a witness testifies that someone's wife was unfaithful, and the husband remains quiet. The Gemara there implies that they both agree that if a witness said that your Taharos became impure and he remained quiet, that the witness would be believed. Similarly, if a witness stated that someone ate forbidden fat and the person remained quiet, he would be believed even though it is not in the witnesses' hands to ascertain that this is true.

Answer: Rabeinu Tam answers that here the case is where the person contradicts him or says that he does not know whether or not this is true. However, the cases in Kidushin are referring to cases where the person remained quiet, which is like admitting.

This is also implied in Yevamos (87b), where the Gemara wants to deduce that a single witness is believed in matters of prohibition (from the case of a witness testifying he ate forbidden fat). The Gemara rejects this as proof because there it is possible because he was quiet, which is like admission.

In the case where his wife was unfaithful, as well, the argument is regarding when the husband was quiet. Abaye therefore holds that when there is a single kosher witness who is not a thief, he is believed.

Implied Question: We usually say that a matter of Arayos is not resolved with less than two witnesses or if there is Kinuy and Stirah with one witness (the process of making a woman into a Sotah). (Note: Why do we allow one witness here?)

Answer#1: Being that the husband here is quiet, the law is that the witness is believed.

Answer#2: Alternatively, this is only according to Rabbinic law (that she is forbidden).

According to Rava, even if he is quiet she does not become forbidden, unless the witness is believed to him like two witnesses.

Observation: Based on this Rabeinu Tam said that if a person is making his friend's wine pure, if he finds his friend and tells him at the first possible opportunity (that he made the wine impure), he is believed even if his friend contradicts him, being that it is within his ability. However, nobody else is believed if he contradicts him or says that he does not know. If he is quiet, the other person is believed. This is also the ruling of Rabeinu Meshulam ben Rabeinu Kelonimus.

If he believes him like two witnesses then she is forbidden, as in the case of the blind man in Kidushin (66a) according to Rava. Even when the witness is not believed, if the husband believes it is true she is forbidden to him due to the principle that a person can create for himself a "forbidden piece" (even though it is not otherwise halachically forbidden). It seems that if he is quiet because he does not know whether or not the witness is telling the truth, it is not called being quiet.

The entire Gemara in Kidushin (ibid.) can be explained where the person says, "Your Taharos became impure before you" or "You knew they were impure." This is clearly correct, as it is like the case where the witness states, "You ate forbidden fat," where being silent is like admittance. (Note: Being silent in these cases is definitely like admittance as he is being accused of knowing, and is still silent.)

Question: This is difficult. Rebbi Yosi himself says in Zevachim (45b) that there is no such thing as Pigul in Korbanos that are done inside (the Heichal), as we derive this from a Korban Shelamim!

Answer: It is not Pigul, but it does become invalid.

When the Gemara here states Pigul, it doesn't specifically mean Pigul. This is like the Gemara in Zevachim (14a). The Gemara states that Rebbi Shimon says that whatever is not placed on the outer Mizbei'ach like a Shelamim does not make one liable for eating Pigul. Rebbi Yosi b'Rebbi Chanina says that Rebbi Shimon admits that the Korban is nonetheless invalid, based on a Kal v'Chomer.

Implied Question: One cannot ask, "How do we know he is believed?" (Note: Why not?)

Answer: It is obvious that in all Korbanos it is possible to have Pigul by all of the four main Avodos.