Populist rage, ideological fracture, economic and technological shocks, geopolitical dangers and an international system studded with catastrophic risk - the early decades of the 21st century may be one of the most revolutionary periods in modern history. But they are not the first. Humans have lived, and thrived, through more than one great realignment. What makes an age a revolutionary one? And how do they end?In this major new work, Fareed Zakaria...