If therefore perfection were by the Levitical priesthood, (for under it the people received the law,) what further need was there that another priest should rise after the order of Melchisedec, and not be called after the order of Aaron?It is objected that the Law was given to the Israelites before the priesthood emerged. This is not so, for the official "giving" of the Law was the Deuteronomic covenant, which was the last event recorded in the Pentateuch and after the creation of the priesthood. All other previous accounts of the Law being given were merely recitations. (And if you really want to get technical, since the establishment of the priesthood was part of the law, it would hardly be incorrect to say that the law was
received under the priesthood, even if chronologically it happened that the priesthood was the last part of the law established.)