The Self-Donation of God, pg. 250:
"Jesus is the true king and therefore “Lord of all." For this reason he is capable of laying down his life in a priestly act as “servant of all.” His priestly office (munus sacerdotale) therefore proceeds from his kingly office and depends upon it. As the true Davidic king, Jesus is also the true Melchizedekian high priest (Ps 110) as the New Testament consistently interprets his messianic role. "