I discovered two quotations by John Calvin, one in his Institutes of the Christian Religion and the other in his Commentary on Genesis where Calvin argues that the rainbow existed before the Noahic Covenant was established. The False Dilemma between the Bible and Science has been a reoccuring theme I've featured, as well has reviewing quotations from great theologians that demonstrate that it is a false dilemma, with special emphasis on quotations by the great Reformers who are the theological grandfathers of those who assert this false either/or between the Bible and Science. (Maybe this theme is my wrestling with the flannel graph of my Sunday School of long ago.) Calvin's example of this false dilemma is the rainbow, and the false dilemma is presented as, the Bible reveals that the rainbow as specially created as a sign and seal of peace to mankind at the establishment of the Noahic Covenant and yet Science tells a different story concerning the ontology of rainbow prior to the Deluge.

In the following two quotations, Calvin discusses the origin of the rainbow in a non-concordant interpretation of Genesis 9:13. The existence of trees, rainbows, and stars is no problem for Calvin's sacramentology, because any existing creature may become a sacramental sign and seal in the same way as any existing nugget of silver may have the sign and seal of Caesar pressed upon it to give it official value. Calvin does not claim that the rainbow came into existence at the time of Noah, but that God has chosen the rainbow from all his created entities to be his special and sacramental sign of peace. So it makes no difference whether the rainbow had existed since the beginning of Creation.

John Calvin's Institutes IV.xiv.18

[...] he gave Adam and Eve the tree of life as a guarantee of immortality, that they might assure themselves of it as long as they should eat of its fruit [Gen. 2:9; 3:22]. Another, when he set the rainbow for Noah and his descendants, as a token that he would not destroy the earth with a flood [Gen. 9:13-16]. These, Adam and Noah regarded as sacraments. Not that the tree provided them with an immortality which it could not give to itself; nor that the rainbow (which is but a reflection of the sun's rays upon the clouds opposite) could be effective in holding back the waters; but because they had a mark engraved upon them by God's Word, so that they were proofs and seals of his covenants. And indeed the tree was previously a tree, the rainbow a rainbow. When they were inscribed by God's Word a new form was put upon them, so that they began to be what previously they were not. That no one may think these things said in vain, the rainbow even today is a witness to us of that covenant which the Lord made with Noah. As often as we look upon it, we read this promise of God in it, that the earth will never be destroyed by a flood. Therefore, if any philosophizer, to mock the simplicity of our faith, contends that such a variety of colors naturally arises from rays reflected upon a cloud opposite, let us admit it, but laugh at his stupidity in failing to recognize God grace, what is gained from these visible sacraments?" as the lord and governor of nature, who according to his will uses all the elements to serve his glory. If he had imprinted such reminders upon the sun, stars, earth, stones, they would all be sacraments for us. Why are crude and coined silver not of the same value, though they are absolutely the same metal? The one is merely in the natural state; stamped with an official mark, it becomes a coin and receives a new valuation. And cannot God mark with his Word the things he has created, that what were previously bare elements may become sacraments?

Calvin, John. Institutes of the Christian Religion. Ed. John T. McNeill. Trans. Ford Lewis. Battles. Philadelphia, PA: Westminster, 1960. 1294-5. Print.

John Calvin's Commentary on Genesis 9:13

13. I do set my bow in the cloud. From these words certain eminent theologians have been induced to deny, that there was any rainbow before the deluge: which is frivolous. For the words of Moses do not signify, that a bow was then formed which did not previously exist; but that a mark was engraven upon it, which should give a sign of the divine favor towards men. That this may the more evidently appear, it will be well to recall to memory what we have elsewhere said, that some signs are natural, and some preternatural. And although there are many examples of this second class of signs in the Scriptures; yet they are peculiar, and do not belong to the common and perpetual use of the Church. For, as it pleases the Lord to employ earthly elements, as vehicles for raising the minds of men on high, so I think the celestial arch which had before existed naturally, is here consecrated into a sign and pledge; and thus a new office is assigned to it; whereas, from the nature of the thing itself, it might rather be a sign of the contrary; for it threatens continued rain. Let this therefore he the meaning, of the words, ‘As often as the rain shall alarm you, look upon the bow. For although it may seem to cause the rain to overflow the earth, it shall nevertheless be to you a pledge of returning dryness, and thus it will then become you to stand with greater confidence, than under a clear and serene sky.’ Hence it is not for us to contend with philosophers respecting the rainbow; for although its colors are the effect of natural causes, yet they act profanely who attempt to deprive God of the right and authority which he has over his creatures.

Calvin, John. Commentaries on The Book of Genesis Vol. I. Trans. John King. Grand Rapids, MI: Baker Books, Philadelphia, PA: Westminster, 2003. 299. Print.