1 The course of reading from the Gospel of John, as those of you who are concerned for your own progress may remember, so proceeds in regular order, that the passage which has now been read comes before us for exposition today. You remember that we have expounded it, in the preceding discourses, from the very beginning of the Gospel, as far as the lesson of today. And though perhaps you have forgotten much of it, at least it remains in your memory that we have done our part in it. What you have heard from it about the baptism of John, even though you retain not all, yet I believe you have heard that which you may retain. Also, what was said as to why the Holy Spirit appeared in the shape of a dove; and how that most knotty question was solved, namely, what was that something in the Lord which John did not know, and which he learned by means of the dove, while already John knew Him, since, as Jesus came to be baptized, he said to Him, “I ought to be baptized by You, and You come to me?” when the Lord answered him, “Suffer it now, that all righteousness may be fulfilled.”
Source: Tractates on the Gospel of John (New Advent)