1) (Vayikra 13:39) ("Then the Cohein shall see, and, behold, if in the skin of their flesh there are dim white bright spots, it is bohak (white scurf) that has blossomed in the skin; it is clean.") "it is bohak … it is clean": This teaches us that bohak is clean (and does not require quarantine). I might think that it does not confer tumah through its source, but it does confer tumah by spreading; it is, therefore, written "that has blossomed (i.e., spread) in the skin; it is clean." I might think that it renders clean a bahereth that issued from it; it is, therefore, written "it" (bohak, is clean, but not a bahereth that issues from it). I might think that it does not render clean a bahereth that issues from it, but it does render clean a bahereth that is adjacent to it; it is, therefore, written "it is clean" but a bahereth or a spreading that either issues from it or is adjacent to it is not clean. 2) Whence is it derived that if he had a nethek the size of a garis and it came to cover his entire head, he is clean? From (Vayikra 13:40) "And a man, if the hair of his head falls out … he is clean." I might think that the beard (if it does not bald) prevents (the head from being tahor if it balds) and that this follows a fortiori, viz.: If the skin of the face and the skin of the (rest of) the flesh, which are separated by something else (the beard) prevent each other (from becoming tahor [if one of them does not turn white, so that it can be considered "all white"]), then the (skin of the head and the beard, which are not separated by anything — how much more so should they prevent each other (from becoming tahor if one of them balds but not the other)! It is, therefore, written "his head" — (Even if) his head (alone balds), and not his beard, "he is clean." 3) — Or perhaps only if his head balds (without his beard balding) is he tahor, but if his beard balds, he is not tahor! It is, therefore, written "And a man," (the superfluous "and") including the beard. 4) — But perhaps the thrust of "man" is to exclude a woman and a minor (and not to include a beard). It is, therefore, written (Vayikra 13:44) "he is a leper," ("he" in that context being superfluous,) to include women and minors). Why, then, is it written "and a man"? To include the beard. If so, why is it written "his head" (and not also "his beard")? His head is clean, (and non-balding of his beard is no deterrent to this.) These are the words of R. Yehudah. 5) R. Shimon says: The (non-baldness of) the beard does prevent the (baldness of the) head (from being tahor), and this follows a fortiori, viz.: If skin of the face and skin of the flesh, which are separated by something else (the beard) prevent each other, (see above), how much more so should head and beard, which are not separated by anything prevent each other! Variantly: Just as we find that anything which is susceptible of the nega of leprosy (and does not sustain that nega) prevents (the attribution to the leper of) "the blossoming of the bahereth (in the whole") — so, all that is susceptible of tumah through the nega of nethek (e.g., the beard in our instance — if it does not sustain the nethek) prevents (the attribution to the leper of) "the blossoming of the nethek" ( — in our instance, in the head). 6) (Vayikra 13:42) ("And if there be on the karachath [the slope of the head towards the nape] or on the gabachath [the slope of the head towards the face] a reddish-white plague-spot, it is blossoming leprosy on his karachath or on his gabachath.") I might think that even if one's head balded because of illness he would be tamei (through a reddish-white plague-spot); it is, therefore, written "karachath" and "gabachath." Just as "karachath" does not grow hair, so "gabachath" does not grow hair (to exclude the above, where he will grow hair upon recovery). Why, then, not say: Just as karachath is at the hands of Heaven, so gabachath is at the hands of Heaven? Whence, then, do I derive (as being tamei) one who ate or anointed himself with neshem (an "irreversible" depilatory)? To that end it is written "baldness," "baldness" (twice) for inclusion (of the above). 7) (Vayikra 13:41) ("And if from the front of his face, his hair fall out, he is gibeach [bald]; he is clean.") This tells me only of the front of his face. Whence do I derive the temples on either side for inclusion? From "And if from the front of his face." What is "karachath" and what is "gabachath"? From the forehead sloping backwards is "karachath." From the forehead sloping forwards is "gabachath." 8) "And if there be … on his karachath or on his gabachath": We are hereby taught that karachath and gabachath do not combine with each other (to form the minimum garis). I might then think that they do not combine with each other, but they do spread from one to the other (to constitute "a spreading"); it is, therefore, written (again) "on his karachath or on his gabachath" — Just as they do not combine with each other, they do not spread from one to the other.
Sifra Tazria Negaim Chapter 10
Tap any verse to see what it echoes — and start a chain or echo from it.