Hashem spoke to Moshe and Aharon, saying, “If a man will have in the skin of his flesh… a tzaras affliction; he will be brought to Aharon the Kohain…” (13:2)
Why is the determination of the tzaras afflictions dependent specifically on a Kohain and not on any learned person like other laws? Also, the Medrash says that when Moshe heard this halacha he was bothered: “Is it honorable for my brother Aharon to be examining tzaras blemishes?” Hashem said to him, “Does he not receive the 24 gifts of the Kohain?” What does this Medrash mean? What is the connection between tzaras and the priestly gifts?
One approach is based on the Gemara in Berachos (5B) that says that “tzaras is like an atoning altar.” If so, one needs a Kohain to officiate for a service which has the function of the altar of the Bais Hamikdash .
But we can explain it on a deeper level as well. The main cause of tzaras is slandering others. Our Sages observe that if one defames his fellow’s lineage he must have a blemish in his own lineage. We are also told that Hashem rest His divine presence amongst the families of pure lineage. Therefore, Hashem gave the task of purifying tzaras to the Kohanim so that they would know which families have questionable lineage and from whom to distance themselves in order to keep their own lineage pure.
This was Hashem’s answer to Moshe. Examining tzaras is not degrading to Aharon. In order for him to receive the special 24 gifts of the Kehunah and keep his lineage pure he needs to know the lines of lineage, which he will understand better if he examines people with tzaras.
(Zera Shimshon)