(Nedarim 52a) If one makes a neder prohibiting himself from wine, he is permitted in cooked food which has in it the taste of wine. However, if he said, “Konam this wine that I will not taste,” and it fell into a cooked dish, if it contains enough to impart flavor to the entire mixture, it is forbidden.
This would imply that if there is not enough to give flavor, it would be permitted. The Ra”n quotes his teachers who ask the following: Something which is forbidden on account of a neder is “something that can become permitted” (davar she’yeish lo matirin), and we have established that anything that can become permitted is not nullified even in a thousand!?
They answer that when we say that it is not nullified even in a thousand, that refers to something that has been mixed with its own kind. But here, when it says, “and it became mixed,” it is referring to something else that is not the same kind, like the case of eggs that were cooked with it. Anything that is mixed with something else that is not its kind is permitted, provided that it does not give flavor, even if it is “something that can become permitted.” The Ra”n cites proof to this from a Mishna in Chalah and a Yerushalmi in our perek.
They, therefore, objected to the statement of the Ri”f in Meseches Chulin concerning bread that was baked in an oven with roasted meat. The Gemora states that it is forbidden to eat it with a dairy sauce even though it has been established that we are not halachically concerned with vapors. The reason it is forbidden is because the bread is “something that can be permitted,” since one may eat it together with meat. For that reason, it is not nullified, even in a thousand. It is evident from the Ri”f that he maintains that “something that can be permitted” is not nullified even in something that is not its kind.
The Ra”n, however, agrees to the Ri”f. When the Mishna here says that “something can become permitted” becomes nullified in something that is not its own kind, that is referring to something that is forbidden now, but will become permitted in the future, like nedarim. For the Ra”n has the following question: Since according to the Chachamim, all forbidden things become nullified in their own kind just as in a different kind, why did the Chachamim make a distinction in the case of “something that can become permitted,” between its own kind and a different kind?
The reason is as follows: The Chachamim and Rabbi Yehudah disagree whether or not something can be nullified in its own kind. Rabbi Yehudah maintains that a forbidden item is not nullified in its own kind, because anything that is similar to another thing does not weaken and nullify it; rather, it preserves it and strengthens it.
The Chachamim disagree and hold that a forbidden item and something which is permitted are not similar to each other, even if they are the same kind. This is because one is forbidden and one is permitted. For it is not fitting to follow the similarity of their substance, but rather the difference in their being forbidden and permitted.
It is for this reason that the Chachamim learned concerning “something that can be permitted” for the sake of being strict towards the opinion of Rabbi Yehudah. For since the forbidden item is not completely different from the permitted one, because the forbidden one will eventually become permitted, we say that it is not nullified in its own kind. It will only become nullified when mixed with a different kind, for the difference that exists between one kind and another will make up for the equality that is added here because it is “something that can be permitted.” It is the difference between kinds that is the cause of nullification, and equality interferes with nullification.
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