Leviticus 4

And before the time of the prophets, when he wanted to show that sins received a much heavier penalty when they were committed by the priests than when they were committed by ordinary people, he commanded as great a sacrifice to be offered for the priests as for all the people. This explicitly proves that the priest's wounds require greater help, indeed as much as those of all the people together. They would not have required greater help if they had not been more serious, and their seriousness is not increased by their own nature but by the extra weight of dignity belonging to the priest who dares to commit them.

He is called by two names, Jesus Christ; Jesus because he is a savior, Christ because he is a priest. With this in mind the divinely inspired prophet Moses gave these two titles to two men eminent above all, changing the name of his own successor in the sovereignty, Auses, to Jesus, and giving his own brother, Aaron, the surname Christ, that through these two chosen men he might represent at once the high priesthood and the kingship of the one Jesus Christ who was to come.