Groping around a familiar room in the dark, or learning to read again after a traumatic brain injury; navigating a virtual landscape through an avatar, or envisioning a scene through the eyes of a character?all of these are expressions of one fundamental property of life, Alain Berthoz argues. They are instances of vicariance, when the brain sidesteps an impasse by substituting one process or function for another. In The Vicarious Brain, Creator of Worlds, Berthoz shows that this capacity is the foundation of the human ability to think creatively and function in a complex world.