Bede the Venerable

(ubi sup.) Thus then John proclaims the Lord not yet as God, or the Son of God, but only as a man mightier than himself. For his ignorant hearers were not yet capable of receiving the hidden things of so great a Sacrament, that the eternal Son of God, having taken upon Him the nature of man, had been lately born into the world of a virgin; but gradually by the acknowledgment of His glorified lowliness, they were to be introduced to the belief of His Divine Eternity. To these words, however, he subjoins, as if covertly declaring that he was the true God, I baptize you with water, but he shall baptize you with the Holy Ghost. For who can doubt, that none other but God can give the grace of the Holy Ghost.