Rainbow, one word that lead your mind going to somewhere to imagine something. I can make it imposible when you said no one ever see rainbow in her life, although it's only in a book.
Most of the time, rainbow is formed after raining and sun shine touch every single drop of water falling from the sky. You know what, a drop of water is nothing, I mean, It can't be used to bath, washing our hand, drinking, and if there is just one drop of water it can't help rainbow appear