John Forbes Nash said this quote

There are things that tend to moderate with age. Schizophrenia is somewhat like that.

~ John Forbes Nash

I would not dare to say that there is a direct relation between mathematics and madness, but there is no doubt that great mathematicians suffer from maniacal characteristics, delirium, and symptoms of schizophrenia.

~ John Forbes Nash

I seem to be thinking rationally again in the style that is characteristic of scientists. However, this is not entirely a matter of joy, as if someone returned from physical disability to good physical health. One aspect of this is that rationality of thought imposes a limit on a person's concept of his relation to the cosmos.

~ John Forbes Nash

It has had a tremendous impact on my life, more than on the life of most Prize winners, because I was in an unusual situation. I was unemployed at the time. I was in good health, but I had reached the age of 66 and beginning to get social security, but I didn't have much of that. I had many years of unemployment before me.

~ John Forbes Nash