And God said, This is the token of the covenant which I make between me and you and every living creature that is with you…
A pledge more appropriate or significant it is not possible to conceive. The theory of the rainbow, physically considered, can be minutely worked out only by the intricate processes of calculus. Every time the arch is formed, there comes into harmonious play a multitude of laws; for example, laws of gravitation, which determine the position of the cloud and the curve of the descending rain and the size and the shape of each molecule; laws of light, according to which the solar rays are absorbed and transmitted and reflected and refracted and polarized, and this, too, in every variety of angle and direction and velocity; laws of geometry, which determine all the angles of incidence and reflection and refraction and interference and polarization; laws of vision and consciousness, by which the beholder perceives on his own retina the image of the beautiful phenomenon, and recognizes it as a rainbow. In other words, the bow in the cloud and our perception of it is the natural result of a perfect adjustment in space and in time of all these multitudinous, complicated, delicatest processes. What a peculiar appropriateness, then, in God's selecting this phenomenon of exquisite beauty as the pledge of His veracity in respect be the constancy of nature, when we remember that the rainbow, involving as it does every time it is formed the perfect adjustment of countless contingencies, is nevertheless of frequent recurrence! What a sublime testimony each recurrence of the rainbow through the ages that have gone before us has been to the infinite regularity with which the Lord of nature has administered His own manifold laws! Had the bow in the cloud never been seen except when Noah and his family gazed on it, we should have ranked it, like the flood, among supernatural events. But the frequent recurrence of the phenomenon, ever and anon spanning our horizon, brings it down within the plane of the natural. Thus the natural becomes itself a sign of the supernatural.
(G. D. Boardman, D. D.)
Parallel VersesKJV: And God said, This is the token of the covenant which I make between me and you and every living creature that is with you, for perpetual generations: