Not long before the financial crash of 2008 a book called The Black Swan – The Impact of the Highly Improbable (Penguin, 2008) written by Nassim Nicholas Taleb was published. The book caused quite a stir in the financial community. The title of the book refers to the common assumption that swans are white. Swans had always been white and it had almost become part of the definition of being a swan, that it is a beautiful, graceful, white bird. The swan-watching community (if there is such a thing) was aghast and confused when a black swan appeared out of nowhere. All that it took for granted was thrown to the wind if such a fundamental assumption as the swan’s colour could be shattered in an instant.