Negaim, Chapter 10, Mishnah 5. Our chapter deals with the third category of nigei adam, the nesek, which affects the hair-bearing areas: the zakan (the bearded part of the face) and the rosh (the scalp). One of the simanei tumah of a nesek is se'ar tzahov, two golden hairs found within the affected patch. This mishnah returns to the question of sequence: what happens when the golden hair was there before the nesek ever appeared?
The four opinions
"Se'ar tzahov shekadam es hanesek: tahor." A golden hair that came before the nesek, so that the nesek did not turn it golden, does not render the man tamei. That is the ruling of the Tanna Kamma. Rebbi Yehudah disagrees and is metamei: to him it makes no difference whether the hair was turned by the nesek or not, and the two golden hairs are simanei tumah in either case. This is the same Rebbi Yehudah who argued with Rebbi Shimon earlier in the chapter on exactly this point, and he restates his position here.
Rebbi Eliezer ben Yaakov rules: "lo metamei velo matzil." The hair has no power to declare the man tamei, and it equally has no power to hold tumah back. Rebbi Shimon rules: "kol she'eino siman tumah banesek, harei hu siman taharah banesek." Anything that cannot serve as a mark of tumah in a nesek automatically serves there as a mark of taharah.
The Rash: what the Tanna Kamma meant
The Rash understands Rebbi Eliezer ben Yaakov and Rebbi Shimon not as introducing fresh cases, but as offering rival readings of the opening Tanna. The first Tanna pronounced a golden hair that arrived first tahor; how much is packed into that one word? For Rebbi Eliezer ben Yaakov, all that was granted is that the hair generates no tumah, while any protective power is denied to it. For Rebbi Shimon, the word carries more: the hair is clean and also shields, for once it cannot mark the nesek as tamei it becomes a mark of its cleanness. Their whole argument thus turns on how the opening statement is to be read. In practice, as was noted earlier, the accepted ruling follows Rebbi Yehudah, who declares such a hair tamei.
The chiddush of the Tiferes Yisroel
The Tiferes Yisroel raises a pointed question. This very machlokes, whether the nesek must be the cause of the hair's becoming golden, was already spelled out earlier in the chapter, together with the decision in favor of Rebbi Yehudah. Why should the same set of opinions be spread before us a second time? He prefaces his answer with "lulei mistafina meirabosai," which is to say: if not for my apprehension before my teachers, I would suggest the following. That is the phrase reserved for a genuine chiddush.
His observation is a matter of language. The earlier mishnah spoke of a hair that is "she'eino hafuch," not turned. Our mishnah adopts a different expression: "se'ar tzahov shekadam es hanesek," a golden hair that preceded the nesek. If both phrases meant the same thing, why would the Tanna trouble himself to change his wording? Perforce, the two mishnayos are not discussing the identical case.
When the earlier mishnah described the hair as not turned, its intent was that the nesek did not take a black hair already growing there and convert it into a golden one; the golden color was not produced by the nesek. But that wording does not tell us that the hair arrived first. It describes a hair and a nesek that emerged as one, in a single moment. Our mishnah, which speaks of a hair that preceded, points to something else entirely: the golden hair was already growing while the skin was still clean of any nesek at all.
Once this is established, each mishnah is stating the stronger version of a different opinion. The earlier mishnah's "not turned" is the ravusa of Rebbi Shimon: he is metaheir not only where the golden hair truly preceded the nesek, but even where the two came into existence simultaneously. Our mishnah's "preceded" is the ravusa of Rebbi Yehudah: even where the hair came first, so that no relationship whatsoever can be drawn between the nesek and the golden hair, and the nesek plainly had nothing to do with it, Rebbi Yehudah is still metamei.
Where does that leave the Tanna Kamma?
It follows that the Tanna Kamma who is metaheir here, and Rebbi Eliezer ben Yaakov who explains him to mean not metamei and not matzil, are speaking only of a golden hair that actually preceded the nesek. What would they say where hair and nesek arose together? Two possibilities present themselves. It may be that in such a case they hold like Rebbi Yehudah, that the hair is tamei and does not save, since there the nesek and the hair did emerge as one. Alternatively, they may hold like Rebbi Shimon in that case, that when the two came together the hair is tahor and also matzil, and their disagreement with him is confined to a hair that came earlier, where they say tahor but not matzil.
Either way, the two mishnayos are no longer a repetition of one another: one draws out how far Rebbi Shimon's taharah extends, and the other draws out how far Rebbi Yehudah's tumah extends. That is the teaching of this mishnah.