
Ambrose of Milan
Catena Aurea · Lukasevangelium 3
Now when all the people were baptized, it came to pass, that Jesus also being baptized, and praying, the heaven was opened, And the Holy Ghost descended in a bodily shape like a dove upon him, and a voice came from heaven, which said, Thou art my beloved Son; in thee I am well pleased.
Now the Spirit rightly shewed Himself in the form of a dove, for He is not seen in His divine substance. Let us consider the mystery why like a dove? Because the grace of baptism requires innocence, that we should be innocent as doves. The grace of baptism requires peace, which under the emblem of an olive branch the dove once brought to that ark which alone escaped the deluge.