Because it is extremely beautiful! Although there is no lack of beauty in the world, the rainbow is the most fitting as a sign of a covenant and promise that God would never again bring a similar flood upon mankind.
The rainbow “recreates” the world. It shows us the beauty of the world as it was meant to be before the tragic flood and the immorality that led up to it.
How was the world before the flood? In the beginning, God created a beautiful and delightful world for mankind. But it was a world for life in a positive and purposeful manner.
However, when mankind began behaving in a manner that was immoral and corrupt, God flooded and virtually “erased” the world. All living beings were removed from the world except for those sheltered in Noah’s ark, which would provide a “reboot” to the world that God originally intended.
The ideal world had all ingredients needed for people to live long, healthy and happy lives. The climate was ideal and the land was fertile. The sunshine and rain were plentiful and sufficient for all agricultural and ecological harmony. People were privy to the most beautiful sights possible.
Unfortunately, mankind chose to ignore the moral imperative of the creation then and refused to see the true beauty of creation. The rainbow is a reminder of this shortcoming and a guarantee that it will not reoccur. The rainbow – comprised of the sunshine and rain of creation - is breathtakingly beautiful and represents the blindness of mankind who ignored God's signs and wonders and continued in their God-less ways.
May we merit to always see the true beauty of the world we live in and take pleasure in lives of “living color”. Meaningful and successful lives that encompass the entire spectrum of the beauty of our world.