1)
(a)The Tana declares Tahor, Nega'im that ...
1. ... a person had prior to Matan Torah, a Nochri prior to his conversion or a baby prior to his birth.
2. ... appear on folds in the skin before they straightened out, on the head or the beard or the Kedach before the hair fell out, or on a Sh'chin, Michvah or Kedach before they healed (and the Nega remains intact, as it does in all the cases in the Mishnah).
(b)We learn all this from the Pasuk "ve'Hayah bi'Mekom ha'Sh'chin Se'eis" - which implies that the Sh'chin precedes the Se'eis (the Siman Tum'ah, and by the same token that the Siman Tum'ah appears at a time when it is subject to Tum'ah), and not vice-versa.
2)
(a)In a case where a Nega appears on ...
1. ... the head or the beard before hair has grown, and hair subsequently grows and falls out - R. Eliezer ben Ya'akov declares them Tamei, and so he does in the parallel case of ...
2. ... a Sh'chin, a Michvah or a Kedach on which the Nega appears before they scar, and they subsequently scar and then heal (see Tos. Yom-Tov (DH 'ha'Sh'chin ve'ha'Michvah' & Tiferes Yisrael).
(b)... because the beginning and the end are a Siman Tumah.
(c)The Chachamim declare him Tahor - since in the middle, a sign of Taharah appeared.
(d)The Halachah is like the Chachamim.
3)
(a)The Mishnah describes ...
1. ... a Baheres (ka'Sheleg) which appear on the skin of a Nochri before he convert, and which, after the conversion, changes its appearance to ke'Sid ha'Heichal, ke'Tzemer Lavan or ki'Kerum Beitzah as - a change le'Kula, as he does ...
2. ...a Se'eis ('ke'Tzemer Rachel) which appear on the skin of a Nochri before he convert, and which, after the conversion, changes its appearance to ke'Loven Beitzah (its Toldah [see Tos. Yom-Tov]).
(b)And when the Tana says Na'asis Mispachas Se'eis O Mispachas Azah, he means that - the appearance of Se'eis (ke'Tzemer Lavan) or Baheres (ke'Sheleg) turn into a Mispachas (its Toldah, either ke'Sid ha'Heichal or ki'Kerum Beitzah, respectively [repeating what we already learned - see also Tiferes Yisrael]).
4)
(a)To describe Lehachmir, the Mishnah presents the case of - a Nega that was initially ki'K'rum Beitzah and then changes to ke'Tzemer Lavan, or was ke'Sid ha'heichal and changes to ke'Sheleg.
(b)The Tana cites a triple Machlokes in this matter. R. Elazar ben Azaryah declares all the above Tahor. The opinion of ...
1. ... R. Elazar Chisma is - Lehakeil Tahor, Lehachmir, Tamei.
2. ... R. Akiva is - Tamei either way.
(c)The Halachah is - like R. Akiva.
5)
(a)The Mishnah declares a plain Baheres ...
1. ... initially or after one week (see Tos. Yom-Tov) - a Musgar.
2. ... after two weeks or after the Kohen declares him Tahor (see Tos. Yom-Tov) - Tahor.
(b)In a case where Simnei Tum'ah appear on a Baheres after the Kohen has declared him a Musgar (either initially or after one week, but before he has a chance to actually lock him up) or Tahor (at the end of two weeks) - the Tana declares him Tamei Muchlat.
(c)And in the reverse case, where he declares him a Muchlat, and before he has a chance to carry out his ruling, the Simnei Tum'ah disappear ...
1. ... initially or after one week - he declares him a Musgar.
2. ... after two weeks or after he has declared him Tahor - he declares him Tahor (see Tos. Yom-Tov).
6)
(a)The Tana rules that someone who removes Simnei Tum'ah from his' skin or who burns a Michyah - has transgressed the La'av ...
(b)... "Hishamer be'Nega ha'Tzara'as" [see Tos. Yom-Tov]).
(c)And he declares someone who does so ...
1. ... before he has been to the Kohen - Tahor.
2. ... after the Kohen has declared it Tamei - Tamei.
7)
(a)R. Akiva asked R. Gamliel and R. Yehoshua whilst they were on their way to Gadvad - what the status will be if he cuts it off whilst he is a Musgar.
(b)They replied that - they did not know the answer, but that they had heard the dual ruling that we just cited.
(c)R. Akiva answered his own She'eilah however, based on the first ruling - in that just as there, he is Tahor because the Kohen did not see the Si'man Tum'ah, so too in a case where he cut it off, before the Kohen declared it Tamei, and so too, a Musgar that the Kohen did not declared a Muchlat (see Tos. Yom-Tov) see Tos. Yom-Tov.
8)
(a)According to R. Eliezer, the Metzora discussed by R. Akiva becomes Tahor when a new Nega appears Tahor (see Tos. Yom-Tov) and the Kohen ultimately declares him Tahor (see Tos. Yom-Tov) - because he considers this an indication that Hash-m has taken pity on him, and that the same would have happened had he not cut off the first Nega.
(b)The Chachamim give two other alternatives; one of them, where it spreads to his entire body. The other - where the Baheres becomes smaller than a G'ris.
9)
(a)The Kohen will tell a person whose Baheres was accidentally cut off - that he is Tahor.
(b)We learn from the Pasuk "Kol Y'mei asher ha'Nega bo Yitma" that - once the Nega is removed, he is Tahor (even if he cut it off himself) and ...
(c)... the reason that the Kohen declare Tamei someone who cut it off on purpose is because of a K'nas.
10)
(a)If the Metzora cut off the Nega on purpose, R. Eliezer rules that it will become subject to Taharah when a new Nega appears and he is cured from it (like his previous ruling). The Chachamim say - only if it spreads to his whole body (see Tos. Yom-Tov).
(b)The Halachah is - like the Chachamim.
(c)The Chachamim do not present the second ruling that they gave earlier (if it becomes smaller than the size of a G'ris) - because that is only applicable there where some of the original Nega remained, which is not the case here.
11)
(a)Both R. Eliezer and the Chachamim agree that, in a case where the Metzora removed the entire Nega plus some of the flesh surrounding it - the Kohen must declare him Tamei.
(b)... because of a K'nas.
(c)R. Eliezer concedes that P'richah will render him Tahor - if he left over a little which he did not cut off ...
(d)... and they argue in a case - where he cut off the entire Baheres only, no more and no less.
12)
(a)It is obvious that an eighth-day Milah overrides the La'av of cutting off a Nega - because if it overrides Shabbos (a La'av which carries with it a Chiyuv Misah), then how much more so that of cutting off a Nega (which is only a regular La'av).
(b)And when the Tana states 'Haysah be'Rosh Orlaso, Yimol' he is referring to - a Milah she'Lo bi'Zemano (one that is performed after eight days).
(c)... based on the principle of Aseh Docheh Lo Sa'aseh (a Mitzvas Asheh overrides a La'av).
(d)It does not override Shabbos however, because, although an Aseh is Docheh a Lo Ta'aseh, it is not Docheh a Lo Ta'aseh and an Aseh or a Lo Ta'aseh she'Yesh bo Kareis, both of which Shabbos is.
Hadran alach 'Elu Behoros'