Negaim, Chapter 1, Mishnah 2. The masechta of Negaim treats the plagues of Tazria and Metzora, afflictions that come from a spiritual defect and require a process of purification, and its opening lines lay out the shades in which nig'ei adam appear: "Maros nega'im shenayim shehein arba'ah," two primary appearances, each with a secondary shade beneath it, so that in all there are four. The baheres is a brilliant white like snow, and its secondary shade is like the whitewash of the heichal, the bright limestone with which the walls of the Kodesh were coated each year before Pesach. Regarding the se'eis, Rabbi Meir holds that the av is like the membrane of an egg and the secondary shade is like the washed white wool of a newborn lamb, while the Chachamim, whose view is the halacha, hold the reverse: the se'eis itself is like white wool, and beneath it is the shade of an egg's membrane.
Once the four are on the table, the obvious question is what practical difference the dispute makes. According to the Rav and most of the meforshim, the nafka mina lies in tzeruf, in whether two different whites appearing on a person's skin can be combined to make up the required size.
The shiur of a gris
A nega must measure a kegris, the size of a certain bean. This measurement appears elsewhere as well, in hilchos niddah, in the laws of kesamim. A woman who has none of the simanim of niddus but finds a stain is not rendered a niddah if the stain does not exceed the size of a gris and a bit more, because such a small stain is attributed not to her own bleeding but to a squashed insect, a bedbug or the like, that left its blood on the garment. Contemporary poskim differ in translating the measure, ranging from a dime, which is the strictest reckoning, to a penny or even a nickel.
Now suppose a person has less than a gris of one shade of white and less than a gris of another, and the only way to reach the shiur is by joining them. When do the two whites combine?
The rules of combination
The Rav's approach yields three rules:
- The two avos, the se'eis and the baheres, combine with one another to make up a gris.
- Each av combines with its own toldah, its own sapachas, the secondary white that belongs to it.
- An av does not combine with the toldah of the other av, and the two toldos do not combine with each other.
With those rules in hand, the machlokes about the se'eis suddenly has teeth. Everyone agrees that the baheres, the white of snow, combines with sid haheichal, since that is its own toldah. The question is what happens with the shades of the se'eis side.
According to the Chachamim, whose se'eis is tzemer lavan, the baheres combines with tzemer lavan, because both are avos, and it does not combine with kerum beitzah, which is only a toldah of the other av. Kerum beitzah and sid haheichal, being two toldos, do not combine with one another.
According to Rabbi Meir, whose se'eis is kerum beitzah, it is exactly the reverse: the baheres combines with kerum beitzah, since the two are avos, and it does not combine with tzemer lavan. The dispute, in short, determines which of the whites are partners and which stand alone.
The Rambam's entirely different reading
The Rambam takes a completely different approach, in the first chapter of Hilchos Tumas Tzara'as, near the end of halacha gimmel, the very Rambam that the Rav cites in mishnah 3. In his view all four shades combine with one another: lavan kasheleg, sid haheichal, tzemer lavan and kerum beitzah all join to make up the shiur.
If so, he asks himself, "lamah manuhu Chachamim," why did the Chachamim bother to count them separately and to formulate the mishnah as two that are four? His answer is that the enumeration is not a din in the nega at all but a din in the kohen. The list exists so that a kohen should understand the shades of white. Any kohen who does not recognize the maros and their names, even after he has been taught them and instructed in them, may not go out to inspect nega'im until he grasps the matter and can point and say: this is the baheres, this is its sapachas, this is the se'eis, and this is its sapachas.
On the Rambam's reading, then, the four shades are the curriculum of the kohen's training. Before a kohen is fit to pronounce a person tamei or tahor, he must be able to tell one white from another and to name what he is looking at. The Torah entrusts the fate of the metzora to a man who has learned to see with precision.