Question: The Rashba asks why the Gemara does not say 'Nazir and Chametz', seeing as Rebbi Akiva Darshens "Kol", in Perek ha'Ta'aroves (Zevachim 82.).

Clarification: It speaks about Chatas and Shelamim: If today's Chatas became absorbed in the Shelamim that was Shechted yesterday, it must be eaten according to the Chumra of the Shelamim - which can no longer be eaten that night.

Clarification (cont.): Whereas if it became absorbed in the Shelamim that was Shechted today, then it must be eaten according to the Chumra of the Chatas - which cannot be eaten tomorrow.

Question: The Lashon of the Beraisa however, is difficult, in that it says 'until it becomes absorbed in its flesh', implying that the Heter became absorbed in the Isur; and it continues 'It becomes Kadosh to be like it', which implies that the Isur became absorbed in the Heter?

Implied Question: The Ri says that in Perek Arba Minim (Daf 37:) the Gemara implies that according to the Rabbanan, both Nazir and Chatas teach us 'Ta'am ke'Ikar'.

Source: Because it says there 'Both are needed (to teach us Ta'am ke'Ikar); since, had the Torah written only Chatas, we would have not have been able to learn Chulin from Kodshim; whereas had it written only Nazir, we would not have been able to learn Chatas from it, seeing as its Isur is more stringent in that even the pits are forbidden'.

Source: Because we learn it from Nazir. It is not an Asmachta, because from Rebbi Akiva, who says that 'Heter Mitztaref le'Isur' by Nazir is subject to Malkos, we can learn what the Rabbanan hold by 'Ta'am ke'Ikar'.

Reference to Question: There is a Kashya on this however, from Perek Kol ha'Basar (Chulin Daf 108.) and from Maseches Avodah-Zarah (Daf 108:) which Tosfos deals with there.

Explanation #1: Rashi explains that in a location where one does not perform the kneading, one transgresses on even less than a k'Zayis.

Question: The Gemara will say shortly 'that this only applies in a dish, but in a house, one is obligated to destroy it', because 'sometimes one gathers them and they end up together'.

Question (cont.): Now according to Rashi, one is Chayav anyway, because in a location where kneading is not performed one is Chayav to destroy even less than a k'Zayis.

Explanation #2: It therefore seems to the Ri, that 'a location that is made to strengthen' refers to the dish, irrespective of whether it is a location where one kneads or not.

Explanation #2 (cont.): Only, a location where one kneads there is more reason to be stringent, due to the concern that, in the course of the kneading, some of that dough will stick to the dough that is being kneaded, or at least, absorb some of its taste.

Explanation #2 (cont.): Consequently, one transgresses on a k'Zayis in a location where the kneading is performed, even if it is merely to strengthen the dish, despite the fact that the owner's intention is clearly to be Mevatel it there ...

Explanation #2 (cont.): Seeing as there are two reasons that are detrimental - a. That there is a k'Zayis, and b. that it is a location where kneading is performed.

Explanation #2 (cont.): Less than a k'Zayis on the other hand, even in a location where kneading is performed, if its purpose is to strengthen the dish, the Rabbanan did not decree, since, due to its minimal volume, it is easy to guard against kneading on it.

Explanation #2 (cont.): Likewise, in a location where kneading is not performed, if it is placed there to strengthen, one does not transgress.

Explanation #2 (concl.): If it is less than a k'Zayis however, which is also not in a location where kneading is performed, is permitted, even if it was not placed there to strengthen the dish.

Clarification: Even though it remains edible, since one is not retaining it in order to eat it, it is Bateil ...

Source: As we find with regard to Tum'ah, as we have learned in 'ha'Or ve'ha'Rotav (Chulin 129.) that it becomes Bateil even though it is still edible ...

Original Source: As we say there 'If one covers a house with seeds (i.e. stalks containing seeds), they become Tahor. Its Tum'ah (i.e. should it contract Tzara'as) is not d'Oraysa, because if it was, we would have a case of food being Metamei a stringent Tum'ah?

Original Source (cont.): And the Gemara answers that the seeds are considered like wood (and are no longer classified as food).

Original Source (cont.): This implies that they are edible.

Conclusion: And the Ri explains that just as they argue regarding Tum'ah, in Perek Bamah Beheimah (Shabbos 52:) where the Rabbanan hold that all vessels lose their status of Tum'ah once their format is changed, whereas Rebbi Yehudah holds that changing their format is only effective if the change is detrimental, but not if it is a positive one ...

Conclusion: So too, do they argue with regard to Pesach.