Whitman's poem "The Voice of the Rain" is not only about the cyclic process in nature but also about the cyclic nature of creative process. Every writer,poet or artist gets experience,ideas or motive from the land,ie, the world/society. He combines it with imagination(which is considered heavenly.so from the sky)and it gets a new form in writing or painting and returns to the world/society or people. So every "Oliver Twist" or every "Animal Farm" or "Gitanjali" is the result of this cyclic process. See how they beautify the world, our lives and thoughts!!
Music is nothing but noise/sound harmonised. One of the music albums of the genius musician Ilayaraja is titled "How to Name it? Nothing but the Wind". A Musician converts the common soounds into melodious music. The sound of a moving train is familiar to all of us. But when A.R.Rahman made it "Chik Puk Chik Puk railey.." or another musician made it "Dhadak Dhadak.." in Bunty aur Bubli, it became melodious music. Kamal Hassan film "Guna" has an excellent and brilliant example of how a conversation can be made a melody. "Kanmani anpode kaaathalan..." That is creativity.
Rain is the creative output of the earth.