He is the way, because he leads us through himself; the door as letting us in; the shepherd, as making us dwell in a place of green pastures and bringing us up by waters of rest, and leading us there and protecting us from wild beasts, converting the erring, bringing back that which was lost, binding up that which was broken, guarding the strong, and bringing them together in the fold beyond, with words of pastoral knowledge. The sheep, as the victim; the lamb, as being perfect; the high priest as the offerer; Melchizedek, as without mother in that nature which is above us and without father in ours; and without genealogy above for who, it says, shall declare his generation? [Isaiah 53:8] and, moreover, as king of Salem, which means peace, and king of righteousness, and as receiving tithes from patriarchs, when they prevail over poser of evil. [Hebrews 7:1-10; 8:1] They are the titles of the Son.
Gregory of Nazianzus (b. 329/330; fl. 372-389), On the Son, Theological Oration 4 (30).21
General Editor Thomas Oden Ancient Christian Commentary on Scripture: New Testament X; Hebrews 234