Catena Aurea on Matthew 21:23–27: Augustine of Hippo

John received his authority to baptize from Him, whom he afterwards baptized; and that baptism which was committed to him is here called the baptism of John. He alone received such a gift; no righteous man before or after him was entrusted with a baptism to be called from himself. For John came to baptize in the water of repentance, to prepare the way for the Lord, not to give inward cleansing, which mere man cannot do.