A woman approached Picasso in a restaurant, asked him to scribble something on a napkin, and said she would be happy to pay whatever he felt it was worth. Picasso complied and then said, “That will be $10,000.”
“But you did that in thirty seconds,” the astonished woman replied.
“No,” Picasso said. “It has taken me forty years to do that.”
Source: What They Don’t Teach You at Harvard Business School by Mark H. McCormack