You see the water; you see the wood; you perceive the dove and do you doubt the mystery?

Accept another testimony. All flesh was corrupted by its iniquities. 'My Spirit,' says God, 'shall not remain in
men, for they are flesh.' By this, God shows that spiritual grace is turned aside by carnal impurity
and by the stain of more serious sin. Therefore, God in His desire to repair what He had given caused the flood, and ordered Noah the just man to embark on the ark. When, as the flood subsided, he first sent
forth a raven which did not return; he afterwards sent forth a dove, which is said to have returned with an olive twig.

You see the water; you see the wood; you perceive the dove and do you doubt the mystery? The water is that in which the flesh is immersed, that all carnal sin may be washed away. All disgrace is buried
there. The wood is that on which the Lord Jesus was fastened, when He suffered for us. The dove is that in whose form the Holy Spirit descended, as you have learned in the New Testament, who inspires peace of soul and tranquility of mind in us. The raven is the figure of sin, which goes out and does not return.

Ambrose, On the Mysteries, 3.10-11.