22 Then, again, it is significant that when God speaks to Noah, and begins anew, as it were, in order, by repetition in various forms, to draw attention to the figure of the Church, the sons of Noah are blessed, and told to replenish the earth, and all animals are given to them for food; as was said to Peter of the vessel, "Kill and eat." That they are told to pour out the blood when they eat; that the former life may not be kept shut up in the conscience, but may be, as it were, poured out in confession. That God makes the bow, which appears in the clouds only when the sun shines, the sign of His covenant with men, and with every living thing, that He will not destroy them with a flood; as those do not perish by the flood, in separation from the Church, who in the clouds of God— that is, in the prophets and in all the sacred Scriptures— discern the glory of Christ, instead of seeking their own glory. The worshippers of the sun, however, need not pride themselves on this; for they must understand that the sun, as also a lion, a lamb, and a stone, are used as types of Christ because they have some resemblance, not because they are of the same substance.
Source: Reply to Faustus the Manichaean (New Advent)