"There is an area of the mind that could be called unsane, beyond sanity, and yet not insane. Think of a circle with a fine split in it. At one end there's insanity. You go around the circle to sanity, and on the other end of the circle, close to insanity, but not insanity, is unsanity."

Source: Quantum Mechanics in Your Face. Lecture at the New England sectional meeting of the American Physical Society, April 9, 1994.