To imagine - to see that which is not there - is the startling ability that has fuelled human development and innovation through the centuries. As a species we stand alone in our remarkable capacity to refashion the world after the pictures in our minds. Traversing the realms of science, politics, religion, culture, philosophy and history, Felipe Fernandez-Armesto reveals the thrilling and disquieting tales of our imaginative leaps - from the first Homo sapiens to the present day. Through groundbreaking insights in cognitive science, he explores how and why we have ideas in the first place, providing a tantalising glimpse into who we are and what we might yet accomplish. Fernandez-Armesto shows that bad ideas are often more influential than good ones; that the oldest recoverable thoughts include some of the best; that ideas of Western origin often issued from exchanges with the wider world; and that the pace of innovative thinking is under threat.