Genesis 9:17

And God said unto Noah, This is the token of the covenant which I have established between Me and all flesh that is upon the earth. Whenever we see the rainbow in the clouds, we should remember the covenant of God toward all flesh, the fact that He-is at peace with His creatures, so far as their outward existence is concerned. The token of God's covenant with which He has connected His promises really guarantees His goodness and grace, possessing power and significance not only for men, but also before God. Every appearance of the rainbow should cause a prayer of thanksgiving to arise to our lips, praising the goodness and mercy of God. It may be remarked in this connection that the changing of the laws of nature indicates that the atmosphere and the climate of the earth before the Flood must have differed materially from that which now obtains, an assumption which is sustained by biological discoveries during the last centuries.