On the Levitical priesthood

Dr. MARK LEUCHTER: Who were the Levites? (TheTorah.com).

The Torah describes the Levites as a landless Israelite tribe who inherited their position by responding to the call of their most illustrious member, Moses, to take vengeance against sinning Israelites, but this account masks a more complicated historical process.

I first learned the theory from my teacher Frank Moore Cross that the Israelite priesthood goes back to competing groups who traced their genealogies back, respectively, to Moses and Aaron. It is admittedly speculative, but it seems to have some explanatory value for untangling the very complicated traditions in the Hebrew Bible about the priesthood.