Leviticus 8: Why Not Moses?

Leviticus 8 describes the ordination of Aaron and his sons as priests for the nation of Israel.  Moses follows the procedure for ordination as previously laid out in Exodus 29.  Interestingly, Moses (not a priest) is the one who sprinkles the anointing oil, offers the sacrifices, and applies the blood.  He is unordained, but he leads the first ordination.  This made me wonder: why was Aaron and his line chosen to be priests - and not Moses?  Wasn't Moses the one in charge, the man who spoke with God as one speaks with a friend?  Why not Moses?

Especially considering Aaron's spectacular failing in the incident with the golden calf (Exodus 32)!  Why would God have chosen Moses' brother to be high priest instead of Moses - choosing someone who was led astray by the people rather than standing firm for the Lord?

One theory urges us to remember that Moses was Aaron's younger brother, after all.  With priestly power designated for Aaron, God is simply reverting to the traditional practice where firstborns held the reins of authority.  Still, I find it curious that Moses would be so instrumental in the ordination ceremony - basically giving authority to his older brother.

Another biblical scholar suggests that Moses was "passed over" for the priesthood and Aaron chosen instead because Moses had argued so long with God at the burning bush.  Eventually, he asked God to "send someone else."  In a way, Moses got his wish and Aaron was selected to be priest in Moses' place.

That's possible (and seems to be the leading Jewish interpretation), but I personally don't like the idea of God settling for something outside of His will, just to be punitive to Moses.  After all, God didn't release Moses from the call to set the people free; He just gave Moses a helper and spokesperson in his brother Aaron.

My own opinion (and I couldn't find any corroboration for this viewpoint in a brief on-line search) is that we have here in the relationship of Moses and Aaron the first instance of "divided government" or "separation of powers."  Moses is the executive, the leader, the strategist.  Aaron is to be the high priest, the embodiment of the Israelite's faith, the practitioner of religious concerns.

These two brothers will go on to be represented later in Israel's history by the kings and priests - two groups that worked with each other but had their own separate spheres of responsibility.  When the kings faltered, the priests could help the nation get back on track.  When the priests grew corrupt, the kings could call them to account.  Moses' ordination of Aaron is the original "separation of church and state!"

Rather than have one person in charge of everything and wear all the hats, God deemed it best to divide up the authority and responsibility into different hands.