What do we know, and how do we know it? What do we now know that we don´t know? And what have we learnt about the obstacles to knowing more? In a time of deepening battles over what knowledge and truth mean, these questions matter more than ever. Bestselling polymath and philosopher A. C. Grayling seeks to answer them in three crucial areas at the frontiers of knowledge: science, history, and psychology. In each area he illustrates how each field has advanced to where it is now, from the rise of technology to quantum theory, from the dawn of humanity to debates around national histories, from ancient ideas of the brain to modern theories of the mind. A remarkable history of science, life on earth, and the human mind itself, this is a compelling and fascinating tour de force, written with Grayling´s verve, clarity and remarkable breadth of knowledge.