I doubt if a single individual could be found from the whole of mankind free from some form of insanity. The only difference is one of degree. A man who sees a gourd and takes it for his wife is called insane because this happens to very few people.
The nearer people approach old age the closer they return to a semblance of childhood, until the time comes for them to depart this life, again like children, neither tired of living nor aware of death.
There are some people who live in a dream world, and there are some who face reality; and then there are those who turn one into the other.