At the beginning of Parshat Emor, Moshe is instructed to inform the Kohanim of a few important rules for them to follow in order to maintain their taharah (purity) that allows them to serve the general Jewish society’s spiritual needs.
A Kohen may not come within a certain distance of a corpse, unless it is one of his close relatives (mother, father, son, daughter, brother and never-married sister). The status of his wife makes for an interesting halakhic discussion (based on how 21:4 is to be understood), but certainly in the absence of a Temple, a Kohen will typically participate in such a funeral.
Kohanim may not create a bald spot in the head, nor shave the peah of the beard (the corner of the head where the skull and jawbone meet at the cheekbone), nor make a gash in the flesh (21:5), for they must be “holy unto G-d and not desecrate His Name” (21:6). There is a group of women whose former relationships disqualify them for a Kohen to marry (21:7).
The underlying reasons given for these rules are because “they present the fire offerings, the food offerings of G-d” and therefore they must remain holy (21:6-8).
A simple reading of the procession of 21:5-6 seems to suggest that the act of not making the bald spot or shaving the peah is a door to achieving holiness (and the holiness achievement is not dependent on the following verse of 21:7). Rabbi Chaim Paltiel noted this (19:3), wondering what to make of Rashi’s principle from last week’s parsha that “whenever you find discussions about immorality, you can find a possibility for holiness.” What does shaving have to do with holiness?
Perhaps we can find an answer from the words of the Alshikh.
In noting that the prohibition against creating a bald spot is in the context of mourning the death of a loved one, Alshikh maintains that the permission granted to become tameh when in mourning is not an all-out allowance to avoid all priestly rules. The Kohen still has responsibilities, and therefore must remain kadosh. Apparently, participation in full acts of mourning lowers one’s level of kedusha (holiness).