On Baptism 8

Next the hand is laid on, calling upon and inviting the Holy Spirit through the benediction. Indeed, human ingenuity will be allowed to summon air into water and, by hands placed over it, to animate their union with another breath of such clearness; and will God not be allowed, on his own instrument, to play a spiritual melody through holy hands? But this too comes from the ancient sacrament, in which Jacob blessed his grandsons, the sons of Joseph, Ephraim and Manasseh, with hands laid on their heads and crossed, and so turned across one another that, forming the shape of Christ, they already then foretold the blessing that was to be in Christ. Then that most holy Spirit gladly descends from the Father upon the bodies cleansed and blessed, and rests upon the waters of baptism as if recognizing his ancient seat, he who glided down on the Lord in the form of a dove, so that the nature of the Holy Spirit might be made known through a creature of simplicity and innocence, since the dove, even bodily, lacks gall. And so he says, “Be simple as doves”; and not even this without the support of a preceding figure. For just as, after the waters of the flood, by which the old iniquity was purged, after the baptism of the world, so to speak, the dove as herald announced to the earth peace from heaven's wrath, sent out from the ark and returning with the olive (a sign held out as peace even among the nations), so by the same arrangement, in its spiritual effect, the dove of the Holy Spirit flies to the earth, that is, to our flesh as it emerges from the washing after its old sins, bringing the peace of God, sent from heaven, where the church is, prefigured by the ark. But the world sinned again; in this respect baptism is ill compared to the flood. And so it is destined for fire, as is the man who after baptism renews his sins; so that this too ought to be received as a sign for our warning.