For John truly baptized with water; but you shall be baptized with the Holy Spirit not many days from now.
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Bede
AD 735
Therefore, when the Lord said John baptized with water, he did not continue with 'you shall baptize,' but with you shall be baptized with the Holy Spirit because neither the apostles nor their followers, who still baptize today in the Church, had the power to baptize except as John did, that is, with water. However, when the name of Christ is invoked, the interior power of the Holy Spirit is present, simultaneously purifies the souls and the bodies of those being baptized. This did not happen in the baptism of John- for the Spirit had not been given.
And, unless I am mistaken, we have also explained what our Lord says: "John indeed baptized with water, but ye shall be baptized with the Holy Spirit."