Someone might ask, “Why would a holy man desire baptism?” Listen to the answer: Christ is baptized, not to be made holy by the water, but to make the water holy, and by his cleansing to purify the waters which he touched.
For the consecration of Christ involves a more significant consecration of the water.
For when the Saviour is washed all water for our baptism is made clean, purified at its source for the dispensing of baptismal grace to the people of future ages.
Christ is the first to be baptized, then, so that Christians will follow after him with confidence.
— Maximus of Turin(d. between 408 and 423): Sermon 100, 1, 3 (CCL 23, 398-400) from the Office of Readings for the Friday between the Feasts of the Epiphany and the Baptism of the Lord @ Crossroads Initiative.