“No one is more dangerously insane than one who is sane all the time. He is like a steel bridge without flexibility, and the order of his life is rigid and brittle.”
— Alan Watts 
Discussion
One of the richest people I know has a quote: “I won’t do business with anyone who doesn’t drink”. His logic is along the same line as Alan Watts here; people who don’t drink are often rigid and sterile. He says he can’t trust them. Of course there are exceptions to the rule, but it’s interesting nonetheless.