What wins wars? Why do empires rise and fall? What makes a great leader? What causes nationalism? How do spiritual movements spread? These are questions in the forefront of our minds today but they meant just as much to people in the past. How did earlier generations tackle them? And how far can historians use the lessons of the past to help to find some answers? Drawing on examples ranging from ancient Greece to Tony Blair's Britain, leading historical thinkers address 20 of the really big questions that have been asked over the centuries about the course of human events. While Richard Evans asks what history is, Ian Kershaw considers how personality affects politics, Lisa Jardine looks at the impact of technology on social change, Felipe Fernandez-Armesto measures the influence of geography, David A Bell assesses what causes nationalism and Colin Renfrew considers how civilisations develop. Others examine why revolutions happen, how spiritual movements spread, why economies collapse, how intellectual movements start, and what impact our physical bodies and our private lives have on changing history. Each essay is accompanied by commentary by a journalist, discussing the differing views of other leading thinkers, today and in the past. The result is a stimulating ride over continents and across centuries in search of answers that are sometimes surprising, often controversial, and all of great relevance to how we live today.