פירוש על נגעים 4:3

ובמכונס (are close together) – that they two hairs are in one place in the plague.

Introduction After comparing white hair and quick flesh to spreading, the Mishnah now compares them to each other.

במפורד – this one on the east side of the plague and that one on the west side.

There are [laws] that apply to white hair that do not apply to quick flesh, while others apply to quick flesh and not to white hair. The introductory statement.

מבוצר (encompassed) – two hairs in the middle of the plague, like a fortress that is in the middle of the city.

White hair causes uncleanness in a boil and in a burn, whether growing together or dispersed, and whether encompassed or unencompassed. White hair is a sign of a nega when it is in a burn or boil (see 3:4). The two requisite white hairs can be on opposite sides of the nega, whereas the quick flesh must all be in the same spot. The white hairs can either be surrounded by the nega, or not. In either case they are a sign of impurity. In contrast, the quick flesh must be surrounded by the nega for it to be a sign of impurity.

אינו מבוצר – like a thread that comes out from the plague, and there is in its midst two hairs, what is not the case with the burning spot that we require [both] encompassed and close together.

There are [laws] that apply to quick flesh, for quick flesh causes uncleanness in scalp baldness and in forehead baldness, whether it was turned or was not turned, it prevents the cleanness of one who is turned all white, and causes uncleanness whatever its color, and these do not apply to white hair. Quick flesh is a sign of uncleanness in scalp or forehead baldness (see 3:6) whereas white hairs are not (he wouldn't really be bald if there were white hairs there, would he?). "Turned" and "not turned" refer to the nega and quick flesh appearing in a certain order. Quick flesh is a sign of impurity whether the nega pre-existed the quick flesh, meaning part of the nega turned into quick flesh, or the quick flesh existed before the nega, meaning the nega arose near the quick flesh. In contrast, the nega must appear before the white hairs for them to be a sign of impurity. If a person turns all white and he is purified but then some quick flesh appears, he is impure (see Leviticus 13:14). But if he turns all white and is purified and then some white hairs appear, he is still pure. Quick flesh can be any color, whereas the white hairs must be white (duh!).

הפוכה ושלא הפוכה (whether it was changed or not changed) – whether the bright white spot on the skin preceded the quick flesh , or whether the quick flesh preceded the bright white spot on the skin/בהרת. What is not the case concerning the white hair, for if it (i.e., the white hair) preceded the bright white spot on the skin, he is pure.

מעכבת את ההופך כולו לבן (hinders [uncleanness] in him who has turned entirely white) – if he was declared a definite leper with quick flesh, and the leprosy blossomed throughout him except for the place of the quick flesh, he is still impure. But if it blossomed throughout even though all of his hair is filled with white hair, he is pure, for the white hair does not hinder (i.e., is not indispensable).