How do we know that Christ's priesthood is greater than Aaron's?

The superiority of Christ’s priesthood is established in Hebrews 5 when the contrast between His eternal priesthood and the temporary nature of Aaron's priesthood is drawn. Aaron and his descendants could only serve for a limited time and needed to offer sacrifices repeatedly. In contrast, Christ’s sacrifice was a once-for-all offering, fully satisfying divine justice and fulfilling the requirements of an eternal covenant. As our eternal High Priest, Christ represents God’s chosen people, actively interceding for them and providing a righteousness that they cannot achieve on their own.