http://www.quora.com/What-was-John-Nash-like-as-a-professor "I was an undergraduate at Princeton in the 1970s, so I guess I encountered Nash at his least stable. One day early in my freshman year, before I knew anything about him, I asked him in the corridor what time it was, and he said "It depends what you mean by time!" What followed made sense only to him and I backed away quickly. He used to do meaningless things that looked like math (e.g., arithmetic with numerology of Soviet leaders' names) on the hallway blackboards.

He tended to wander around campus in somewhat disheveled clothes and sneakers, often smoking weed. The police would talk to him but not trouble him about the pot; I guess they had better things to do."