(R. Avahu citing R. Yochanan): Heter does not join to Isur [to comprise a Shi'ur to obligate someone], except for Isurei Nazir, for it says "Mishras" (a Nazir is liable for eating bread that absorbed wine. Surely, the bread joins to the Shi'ur - if there was a Shi'ur of wine itself, we would not need "Mishras"!)

(Ze'iri): Also regarding the Isur of Haktaras Chametz, Heter joins to Isur.

Question: This is like R. Eliezer, who expounds "Kol" - if so, Heter should join to Isur also regarding Chametz during Pesach!?

Answer: It does! Ze'iri said his law regarding Haktarah to show that he argues with Abaye:

(Abaye): Even less than a k'Zayis is considered Haktarah (therefore, there is no need to join to a Shi'ur).

Ze'iri teaches that one is liable only for Haktarah of a k'Zayis.

Rav Dimi recited this teaching [of R. Yochanan].

Question (Abaye - Mishnah): If garlic and oil of Chulin were in a thick porridge of Terumah, and a Tevul Yom touched part [of the Chulin], it all becomes Tamei;

If the porridge was Chulin and the garlic and oil were Terumah; and a Tevul Yom touched part [of the Terumah], he is Metamei only the place he touched.

Question: Why does the place he touched become Tamei?

Version #1 (our text, Rashi): [Mid'Oraisa,] the spices [of Terumah] are Batel to the majority (the whole mixture is Chulin - a Tevul Yom does not Metamei Chulin)!

Version #2 (Tosfos): The place he touched is smaller than k'Beitzah (it is not Mekabel Tum'ah mid'Oraisa - regarding mid'Rabanan laws, the Terumah is Batel to the Chulin)!

Answer (Rabah bar bar Chanah, citing R. Yochanan): [The Terumah is not Batel] because a Zar is lashed [mid'Oraisa] for eating a k'Zayis [of the mixture].

(Summation of Abaye's question): One is liable for eating a k'Zayis of the mixture because the Chulin (Heter) joins to the Terumah (Isur)!

Answer (Rav Dimi): No - he is lashed when the mixture contains a k'Zayis [of Terumah] bi'Chdei Achilas Pras (within a half loaf, i.e. three or four eggs worth of the mixture. Really, Kedei Achilas Pras is the time to eat a half loaf - if there is a k'Zayis within a half loaf, one can [eat normally and] consume a k'Zayis of Terumah in this time.)

Question (Abaye): Does the Torah really obligate one for eating a k'Zayis [of Isur] bi'Chdei Achilas Pras?

Answer (Rav Dimi): Yes!

Question (Abaye): If so, why do Chachamim argue with R. Eliezer, and exempt one who eats Kutach on Pesach?

[Counter-question: You explain that Heter joins to Isur - how do you explain why Chachamim exempt?! Tosfos deletes this from the text, for only R. Akiva says that Heter joins to Isur.]

Answer (Rav Dimi): Kutach is different - one does not normally eat a k'Zayis [of Chametz] bi'Chdei Achilas Pras:

If he eats it straight - this is abnormal (Rashi - therefore, he is exempt; Tosfos Nazir (36B) - Chachamim discuss only what is normal, but indeed, one who eats it straight is liable).

If he eats it as a dip - he will not eat k'Zayis bi'Chdei Achilas Pras!

Question (Abaye - Beraisa): If there are two pots, one of (i.e. containing) Terumah and one of Chulin, and two spice mortars in front of them, one of Terumah and one of Chulin, and the contents of each mortar fell into a pot (we do not know which fell into which):

Both pots are permitted (the Terumah to Kohanim, the Chulin even to Zarim), because we [are lenient to] assume that the Terumah fell into the Terumah, and the Chulin into the Chulin.

If k'Zayis bi'Chdei Achilas Pras is [forbidden] mid'Oraisa, why are we lenient? (Perhaps the Terumah fell into the Chulin, and it is forbidden to a Zar- we must be stringent about a Safek Isur Torah!)

Answer (Rav Dimi): Terumah of spices is only mid'Rabanan (Rashi - mid'Oraisa, Terumah only applies to grain, wine and oil; we are lenient about a Safek Isur mid'Rabanan).

Question (Abaye - Beraisa): If there are two boxes, one of Terumah and one of Chulin, and two Sa'im (measures of grain), one of Terumah and one of Chulin, and one Se'ah fell into each box:

Both boxes are permitted, because we say that the Terumah fell into the Terumah, and the Chulin into the Chulin.

If k'Zayis bi'Chdei Achilas Pras is mid'Oraisa, why are we lenient?!

Answer: The Beraisa discuss nowadays, when Terumah is only mid'Rabanan, therefore we are lenient.

Question: How can "Mishras" teach that Heter joins to Isur - it teaches something else!

(Beraisa): "Mishras" teaches that Ta'am k'Ikar (if an Isur can be tasted in a mixture, the mixture is forbidden):

If one soaked grapes in water, and the water absorbed their taste, a Nazir is liable for drinking it.

We learn from here to all Torah prohibitions:

Isurei Nazir are not permanent, they are not Isurei Hana'ah, and the Isurim can be permitted [even within 30 days, one can annul his vow to be a Nazir], nevertheless Ta'am k'Ikar;

Kil'ai ha'Kerem is permanently forbidden, it is Asur b'Hana'ah, and the Isur cannot be permitted - all the more so, Ta'am k'Ikar!

Similarly, Orlah is more severe than Nezirus in two of these three ways, all the more so Ta'am k'Ikar! (Orlah is Isurei Hana'ah; Rashi - Orlah cannot be permitted [within the duration of the Isur, i.e. three years], but the Isur [on the tree] is not permanent; R. Tam - this refers to Orlah fruits of the fourth year - they are permitted through redemption or bringing them to Yerushalayim, but their Isur is permanent, i.e. it has no time limit.)

Answer: The Beraisa is Chachamim - R. Yochanan's law is according to R. Akiva.

Question: Where did R. Yochanan learn that R. Akiva holds that Heter joins to Isur?

Answer #1 (Mishnah - R. Akiva): Even if he (a Nazir) soaked his bread in wine, and there is enough Letzaref (to join) to a k'Zayis, he is liable.

Rejection: Perhaps he is liable only if there is a k'Zayis of wine [and 'Letzaref' means to comprise]!

Question: If so, what does R. Akiva teach?

Answer: He teaches that one is liable even though the wine is only absorbed.

Answer #2 (Beraisa - R. Akiva): If a Nazir soaked his bread in wine and ate a k'Zayis of bread and wine, he is liable.

Question: [Since R. Akiva uses "Mishras" to teach that Heter joins to Isur,] what is his source for Ta'am k'Ikar?

Answer #1: He learns from meat and milk.

The meat only absorbs a taste of milk (or vice-versa), and it is forbidden - we learn to all similar cases.

Chachamim do not learn from meat and milk, because it is a Chidush (exceptional).

Question: Why is it a Chidush?

Suggestion: This is because each is permitted by itself, but together they are forbidden.

Rejection: This is not a Chidush - the same applies to Kil'ayim (planting or grafting diverse species, working with or mating different species of animals, or wearing Sha'atnez)!

Answer: If one soaks them together they are permitted, but if they are cooked together, they are forbidden.

Rejection: For this reason, also R. Akiva cannot learn from meat and milk!

Answer #2 (Rav Ashi): Rather, he learns from Gi'ulim (absorbed tastes of Isur in Kelim) of non-Jews.

These Kelim have only absorbed taste, yet the Torah forbade [using the Kelim taken from Midyan before Kashering them] - the same applies to Heter with a taste of Isur!

Chachamim don't learn from there because it is a Chidush:

Normally, the Torah permits detrimental tastes (Neveilah is forbidden only if a Ger Toshav would eat it, not if it is spoiled); regarding Gi'ulei Nochrim, they are forbidden (all absorbed tastes become detrimental after a while).

Question: [Since it is a Chidush,] why does R. Akiva learn from it?

Answer: He holds like Rav Chiya brei d'Rav Huna:

(Rav Chiya brei d'Rav Huna): The Torah forbids only vessels used in the last 24 hours - in this time, absorbed tastes are still beneficial.

Chachamim say that even within 24 hours, the absorbed taste is slightly ruined.

Question (Rav Acha brei d'Rav Avya): From Chachamim we should be able to learn about R. Akiva's opinion!

Chachamim say that "Mishras" teaches [regarding Nazir] that Ta'am k'Ikar, and we learn to all Isurim - R. Akiva holds that "Mishras" teaches [regarding Nazir] that Heter joins to Isur, also he should learn to all Isurim! (Why does R. Yochanan say that it applies only to Isurei Nazir?)