In the initiation rites that Moshe Rabbeinu performed for Aharon and the rest of the kohanim we find an interesting ritual. The blood of one of the sacrifices was sprinkled, not only on the alter, which is usual, but upon the kohanim themselves.
It stands to reason that if the kohein is to be my representative to Hashem, he needs to be dedicated to the purpose. So the hands and feet of the kohanim were baptized by the blood to symbolize their job as an extension of our hands and feet in performing the Avodah.
There was a third element in the sprinkling – the ear. What are we to learn from here ? Is the kohein supposed to be my ear as well ? Definitely not. Rather, we see that the kohanim are given the subtle message that to serve as the representatives of other Jews is only possible when they themselves are absolutely attuned to their own obligations. The kohanim must be able to hear clearly the commandments of Hashem and only afterwards are they fit to assist His people in their service of Him.
An additional thought; the kohanim's mouth wasn't sprinkled. This may teach us that despite the kohein being our shaliach in performing a given service – we need no intermediary to pray before the One above. We may not all be holy enough to bring korbanos – but we are all fit to sing the praises of our creator.