Capital in the 21st century is a work of extraordinary ambition, great originality and impressive rigor. It guides our entire understanding of economics in new directions and confronts us with sobering lessons for our present. Thomas Piketty shows that modern economic growth and the spread of knowledge have enabled us to avert inequality on the apocalyptic scale predicted by Karl Marx. But we have not changed the structures of capital and inequality to the extent that the optimistic decades after the Second World War suggested. Instead, the main driver of inequality - that profits from capital are higher than growth rates - now threatens to produce extreme forms of inequality that threaten social peace and undermine the values of democracy. But economists.