Book excerpt: What goes on in our head when we have a thought? Why do the physical events that occur inside a fistful of gelatinous tissue give rise to the world of conscious experience? In The Universe of Consciousness , Gerald Edelman and Giulio Tononi present for the first time a full-scale theory of consciousness based on direct observation of the human brain in action. Their pioneering work, presented here in an elegant style, challenges much of the conventional wisdom about consciousness. The Universe of Consciousness has enormous implications for our understanding of language, thought, emotion, and mental illness.