A. C. Grayling is one of the foremost minds of his generation and his new book explores some of the biggest questions that face humanity. What do we know, how do we know it and what is left to find out? In this wide-ranging conversation, he and Dan attempt to tackle some of these important questions. They discuss the incredible progress humanity has made in the last century, how history informs and helps us understand our world and how much there is still to learn about our ancient past and beyond.