Again, as always, much/most of this will only be intelligible to people who have a gemara in front of them. The notes toward the end regarding kohanim and cemeteries today are, to me, particularly interesting.
The definition of minimum hair-length here is reminiscent of the discussion of the haircuts of the king and kohen gadol; see Sanhedrin 22 for more.
The discussion of whether hair grows “at the base” or “at the end” reminds me of a shailah I once received regarding mikvah for a woman whose hair was in cornrows, and which she never intended to un-do. While the real question was about chatzitzah and intent, I wondered whether, if the hair grew from the head, that meant the hair currently in the cornrow would eventually come out. Of course, that’s not what happens – but it was an interesting question nonetheless.
The Rosh explains that the “stringency” of the metzora is his requirement to shave off all of his hair.
The standard of two hairs here as the definition of “hair” is reminscent of the standard for פרה אדומה (two non-red hairs disqualify) and the definition of puberty. And, perhaps, various laws of מלאכה on Shabbos.
Tosafos מחכו points out the irony of R’ Yosi b”r Chanina laughing at a comment in Sanhedrin 17b, and here having his own comment ridiculed.
On the issue of a Nazir unintentionally pulling out hair as he combs, we encounter an issue which has always troubled me, in many areas of Halachah: We invoke the principle of דבר שאינו מתכוון, that lack of intent translates into reduced liability, in many areas of law. The only area where intent should matter, though, is the laws of Shabbos, where the Torah specifies מלאכת מחשבת, intentional acts of melachah! I must be missing something, but I don’t know what it is.
Note that there are two explanations for the discussion here, regarding the Nazir’s unintended shave. Our edition seems to view the issue as simply about intent, or lack thereof. The Rosh, though, has a different edition and seems to view it as also being about פסיק רישיה, guaranteed results. As in the laws of Shabbos, an unintended but guaranteed result would be considered a violation.
The Rosh notes that the boxed nazir in the cemetery cannot be liable for becoming טמא unless he actually helps the other party open his box.
How could one warn a Nazir not to become טמא for being in the room with a גוסס (a person who is very, very close to death)? Perhaps the patient will not die while the Nazir is present! The Rosh suggests that a doubtful warning is acceptable here, because most גוססין do die in short order.
The Rosh notes that – based on our Gemara - a Kohen may not attend a cemetery even to bury a relative, for he will encounter other graves on his way out. This is why we traditionally bury kohanim and their families in the outermost area. However, we haven’t really solved the problem, because we still have cemetery gates, so that the Kohen cannot depart directly from the grave!
Tosafot and the Rosh appear to disagree regarding permissibility for a Kohen to come into contact with tzaraat and זיבה from a non-relative; the Rosh specifies a relative, Tosafot במותם does not. Presumably the Rosh’s position is based on the pasuk from which this lesson is derived, in which relatives are specified.