It is indisputable that a lesser person is blessed by a greater. And whereas men subject to death receive tithes, Scripture testifies that this man lives on. Levi, who receives tithes, was, so to speak, tithed in the person of his father, for he was still in his father's loins when Melchizedek met Abraham.
If, then, perfection had been achieved through the levitical priesthood (on the basis of which the people received the law), what need would there have been to appoint a priest according to the order of Melchizedek, instead of choosing a priest according to the order of Aaron? When there is a change of priesthood, there is necessarily a change of law. Now he of whom these things are said was of a different tribe, none of whose members ever officiated at the altar. It is clear that our Lord rose from the tribe of Judah, regarding which Moses said nothing about priests. The matter is clearer still if another priest is appointed according to the likeness of Melchizedek: one who has become a priest, not in virtue of law expressed in a commandment concerning physical descent, but in virtue of the power of a life which cannot be destroyed. Scripture testifies: "You are a priest forever according to the order of Melchizedek."