Former Rav-Shaliach, Bnei Akiva England
Currently Executive Director, Project Aseret
The Kohanim have been separated and elevated from the rest of Am Yisrael:
In Judaism we do not understand Kedusha (holiness) to be some lofty saint-like lifestyle, but rather Kedusha is achieved by living an earthly life and within that separating ourselves from engrossing too much in the earthly. For the whole of Am Yisrael this is achieved by the mitzvot, and specifically by those mitzvot of forbidden foods and forbidden relations. (The Rambam, for example, combines these two elements in the same book – Sefer HaKedusha). The Kohanim are given many more mitzvot and this is in order to suit their lofty level of Kedusha, for it is the mitzvot that we do which increase our Kedusha: אֲשֶׁר קִדְּשָׁנוּ בְּמִצְוֹתָיו. Reb Tzadok HaKohen of Lublin teaches that every Kohen that is a descendent of Aharon is on a lofty level. It may be that we cannot see this Kedusha when looking at him, but these are matters which go far beyond what meets the human eye.
However, Hashem does not hand out privileges, but rather responsibilities. For Am Yisrael, being the chosen people means being a nation that has to set an example for the rest of the world. And for the Kohanim, being separated produces the responsibility to bring atonement for the nation.
The בִּגְדֵי כְּהֻנָּה (Kohanim’s garments) are an essential part of the Kohanim’s worship in the Mishkan and the Mikdash. Whether they are a mitzvah or a hechsher mitzvah (a precondition to performing the mitzvah of avodat hakohanim), they are nevertheless בִּגְדֵי קֹדֶשׁ (holy garments). What is it that is so special about the בִּגְדֵי כְּהֻנָּה? There are a variety of opinions: one is that the clothes are special because they glorify the Mishkan, and the Zohar says that they allow the Divine presence to dwell amongst us. Other commentators focus on what the clothes do for the Kohanim themselves, whether to give them honour or to help sanctify their thoughts. The latter has double meaning to it. The clothes the Kohen wears will affect his thoughts on an external level, just like any person wearing ceremonial clothes would feel more important or more engrossed in whatever those clothes represent. However, on an internal level, the בִּגְדֵי כְּהֻנָּה which are בִּגְדֵי קֹדֶשׁ do actually sanctify the Kohanim.
Of all the commentaries, it is perhaps that of the Netziv which best complements the idea with which we began, when he explains that the special בִּגְדֵי כְּהֻנָּה help the Kohanim to separate themselves from the rest of Israel and achieve higher levels of righteousness.