John Chrysostom — as excerpted in the Catena Aurea on John 1:32-34

“(Hom. xvii. [al. xvi.] 3) The Father having sent forth a voice proclaiming the Son, the Holy Spirit came besides, bringing the voice upon the head of Christ, in order that no one present might think that what was said of Christ, was said of John. But it will be asked: How was it that the Jews believed not, if they saw the Spirit? Such sights however require the mental vision, rather than the bodily. If those who saw Christ working miracles were so drunken with malice, that they denied what their own eyes had seen, how could the appearance of the Holy Spirit in the form of a dove overcome their incredulity? Some say however that the sight was not visible to all, but only to John, and the more devotional part. But even if the descent of the Spirit, as a dove, was visible to the outward eye, it does not follow that because all saw it, all understood it. Zacharias himself, Daniel, Ezechiel, and Moses saw many things, appearing to their senses, which no one else saw: and therefore John adds, And I saw and bare record that this is the Son of God. He had called Him the Lamb before, and said that He would baptize with the Spirit; but he had no where called Him the Son before.”