In this book, the renowned philosopher and polymath Alain Badiou tells the story of the first five decades of his life, from 1937 to 1985, setting it within the political history of the twentieth century. Born in Morocco on the eve of catastrophic conflict, Badiou's childhood and youth were marked by the Second World War and the Algerian War, experiences that would shape his political consciousness. Badiou honed his political convictions as an activist and organizer among students and workers and in solidarity with the Algerian independence movement, but his life was upended and transformed by May '68 in ways that were profoundly consequential for his philosophical thought. By weaving his philosophical ideas into the narrative of his life, we see how the concepts for which Badiou is well-known – such as subject, being, event and truth – operate in the domain of experience and history. Written in an engaging and often playful style, this book illuminates both the unique trajectory of a major philosopher and the turbulent history of the twentieth century, showing how the latter shaped the thinking of a man who has come to embody the very idea of political commitment and radical political thought.