There is an intimate connection between creativity of all kinds, including original thought, and mental illness. Just check out a few bios of key artists and scientists from history.

The 'normal' mind is the mind whose thoughts run straight, as if on rails. The destination is sure to be reached but the normal mind will rarely see exotic vistas.

The creative mind is chaotic, changing, unstable. It goes every which way. Nine times out of ten that leads nowhere. But that tenth time is a thought that may change the whole world or an image that moves the hearts of millions.

Its ugliness and beauty in one package. What is good for humanity is rarely good for the individual.