Exodus 15:10

7. Thus, then, the bridge over the river being broken, the passageway settled down, and immediately the boats with the men disappeared in the depths, and that most impious one himself first of all, then the shield-bearers who were with him, as the divine oracles foretold, “sank like lead in the mighty waters”; so that those who obtained the victory from God, if not in words, at least in deeds, like Moses, the great servant of God, and those who were with him, fittingly sang as they had sung against the impious tyrant of old, saying, “Let us sing unto the Lord, for he hath gloriously glorified himself; horse and rider hath he thrown into the sea; a helper and a protector hath he become for my salvation;” and “Who is like unto thee, O Lord; among the gods, who is like unto thee glorious in holiness, marvelous in glory, doing wonders.”

And already he was approaching very near Rome itself, when, to save him from the necessity of fighting with all the Romans for the tyrant’s sake, God himself drew the tyrant, as it were by secret cords, a long way outside the gates. And now those miracles recorded in Holy Writ, which God of old wrought against the ungodly (discredited by most as fables, yet believed by the faithful), did he in every deed confirm to all alike, believers and unbelievers, who were eye-witnesses of the wonders. …

If any one supposes that this want of mutual harmony between his life and a single one of its circumstances is quite unimportant, let him be taught the meaning of our maxim by looking at the management of a house. The master of a private dwelling will not allow any untidiness or unseemliness to be seen in the house, such as a couch upset, or the table littered with rubbish, or vessels of price thrown away into dirty corners, while those which serve ignobler uses are thrust forward for entering guests to see. He has everything arranged neatly and in the proper place, where it stands to most advantage; and then he can welcome his guests, without any misgivings that he need be ashamed of opening the interior of his house to receive them. …

20. And this may also be gathered from the Song of Moses, for he, after leading the people of the Jews through the sea, acknowledged the operation of the Father, the Son, and the Holy Spirit, saying: “Thy Right Hand, O Lord, is glorious in power, Thy Right Hand, O Lord, hath dashed in pieces the enemy.” Here you have his confession of the Son and of the Father, Whose Right Hand He is. And farther on, not to pass by the Holy Spirit, He added: “Thou didst send Thy Spirit and the sea covered them, and the water was divided by the Spirit of Thine anger.” By which is signified the unity of the Godhead, not an inequality of the Trinity.

12. There is also a third testimony, as the Apostle teaches us: “For all our fathers were under the cloud, and all passed through the sea, and were all baptized to Moses in the cloud and in the sea.” And further, Moses himself says in his song: “Thou sentest Thy Spirit, and the sea covered them.” You observe that even then holy baptism was prefigured in that passage of the Hebrews, wherein the Egyptian perished, the Hebrew escaped. For what else are we daily taught in this sacrament but that guilt is swallowed up and error done away, but that virtue and innocence remain unharmed?