There is something special about rainbows. They demand that one look at and appreciate their beauty. A few weeks ago I was privileged enough to see a double rainbow overlooking the ocean here in Brazil (it reminded me of a funny YouTube video I once saw about double rainbows, but that's for another time). I can't help but think that, when Noah saw the first rainbow, he was in awe of its brilliance just as I always am. The magnificent light refracted across droplets of water was a reminder that the mass carnage he had just experienced would never again be unleashed on humanity. Since that time, no flood has been so great as to cover the entire surface of the earth, and rainbows serve a reminder to us that God has made a promise. And because He is a gentleman, He will certainly keep it.
Once again, God's grace shines through. It's not that humanity didn't (and doesn't!) deserve another flood. After all, just a few verses later, even Noah is caught up in sinful living. And shortly thereafter, the kingdom of men decided to try to honor itself by building the Tower of Babel – an effort that God quickly squelched by confusing the language. Apparently, starting over with the world did not alleviate the problem of sin. Yet God has been faithful in keeping His promise.