
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.
We have seen the Spirit, but in a bodily shape, and the Father whom we cannot see we may hear. He is invisible because He is the Father, the Son also is invisible in His divinity, but He wished to manifest Himself in the body. And because the Father did not take the body, He wished therefore to prove to us that He was present in the Son, by saying, Thou art my Son.