(Ula): R. Meir and R. Shimon argue in a case that it initially improved the taste and later was Pogem, but all agree that if it was Pogem from the beginning, it is permitted.

Question (R. Chana - Beraisa): If (forbidden) wine (or vinegar) fell into lentils (or grits), the food is forbidden;

R. Shimon permits it.

Even though it (vinegar) is Pogem from the beginning, the Tana'im argue!

Answer (Ula): If one understands the Beraisa, this is not difficult;

The case is, the vinegar fell into cold grits. Later, they were heated. Initially it was li'Shvach, and later it was li'Fgam.

(R. Yochanan): They argue in a case that it was Pogem from the beginning.

Question: Does he mean that they argue only in a case that it was Pogem from the beginning, but if it originally improved the taste and later was Pogem, all permit?

Or, do they argue even in a case that it was Pogem from the beginning?

This question is not resolved (now. It is resolved through the Beraisa on Amud B - Tosfos.)

Support (for R. Yochanan - Rav Amram - Mishnah): If Se'or (sourdough, a fermenting agent) of Chulin fell into a dough, and it was enough to ferment it and it fermented it, and afterwards, Se'or of Terumah or Kilai ha'Kerem fell in, and it was enough to ferment it, the dough is forbidden;

R. Shimon permits it.

Even though the forbidden Se'or is Pogem from the beginning (it overferments the dough), the Tana'im argue!

Rejection (R. Zeira): That is not considered Pogem from the beginning. Even though it harms the taste, it is li'Shvach in another respect. It enables the dough to ferment other doughs.

Support (for R. Yochanan - Beraisa): If Se'or of Terumah and Se'or of Chulin fell into a dough, and each was enough to ferment it by itself, and they fermented it, it is forbidden;

R. Shimon permits it.

If the (Se'or of) Terumah fell in first, all forbid it;

If the Chulin fell in first, and then the Terumah or (Se'or of) Kilai ha'Kerem, the dough is forbidden;

R. Shimon permits it.

Even though the forbidden Se'or is Pogem from the beginning, the Tana'im argue!

Rejection: We can reject the support as R. Zeira did above!

Support (Beraisa): If (forbidden) wine (or vinegar) fell into lentils (or grits), they are forbidden;

R. Shimon permits it.

Even though it is Pogem from the beginning, the Tana'im argue!

Suggestion: We can reject the support as Ula answered this question above. The case is, the vinegar fell into cold grits, and later they were heated. Initially it was li'Shvach, and later it was li'Fgam.

Rejection: They do not argue when it was initially li'Shvach!

(Beraisa): If the (Se'or of) Terumah fell in first, all forbid it.

Conclusion: They argue (only) in a case that it was li'Fgam from the beginning.

Question: Why are the three clauses necessary?

Granted, the Seifa (wine or vinegar that fell... ) is needed to teach that they argue in a case that the Isur was Pogem from the beginning;

The middle clause (Se'or of Terumah fell in, then Se'or of Chulin) is needed to teach that forbid when it was initially li'Shvach and later li'Fgam. (We do not ask about when the Chulin fell in first, which we already know from the Reisha. It was merely taught along with when the Terumah fell first);

Why is the Reisha (Se'or of Terumah and Chulin fell in together) needed?

Chachamim forbid when the Isur was Pogem from the beginning, without any Shevach, and all the more so, when there was Shevach!

Answer (Abaye): The first clause teaches a Chidush according to R. Shimon;

Chachamim say that the Terumah was li'Shvach, for it helped the dough to ferment faster;

R. Shimon says, since the Terumah and Chulin together were li'Shvach, and later they were Pogem together, the dough is permitted.

Question: R. Shimon should say that the Terumah and Chulin join to forbid the dough!

Answer: This is like he taught elsewhere, that two forbidden foods do not join to forbid.

(Mishnah): Orlah and Kil'ayim (that fell into Chulin less than 200 times their combined volume) join to forbid it;

R. Shimon says, they do not join.

A case occurred in which a mouse fell into beer. Rav forbade the beer.

(Rabanan): He forbids Nosen Ta'am li'Fgam.

Rejection (Rav Sheshes): Normally, he permits;

Sheratzim (rodents) are different. They are repulsive, and people would avoid them even if they were permitted;

Therefore, surely their Isur applies even when they are Nosen Ta'am li'Fgam.

Question (Rabanan): If it is a Chidush (and we do not distinguish Nosen Ta'am li'Shvach from li'Fgam), we should not distinguish and say that they are Metamei whether they are moist or dry!

(Mishnah): The following are Metamei if they are moist, but not if they are dry - ...Sheratzim ...

Counter-question (Rav Sheshes): Semen is repulsive. Will you say that it is Metamei even when it is dry?!

That very Mishnah teaches that also semen is Metamei only when it is moist!

Answer (Rav Sheshes): You must say that "Shichvas Zera" refers to semen able to Mazri'a (conceive), i.e. it is moist;

Answer (Rav Sheshes): Likewise, we expound "b'Mosam" (written regarding Sheratzim) - like when they first die, i.e. moist.

Question (Rav Simi of Neharde'a): Mice are not repulsive. They are served on kings' tables!

Answer: City mice are repulsive. Wild mice (squirrels) are not.

(Rava): The Halachah is, Nosen Ta'am li'Fgam is permitted. I do not know Rav's reason.

Perhaps Rav forbids Nosen Ta'am li'Fgam, and the Halachah is not like Rav;

Or, Rav permits Nosen Ta'am li'Fgam, but mice improve beer (they strengthen it).