Martin Heidegger is one of the foremost and most influential thinkers of the 20th century. He is also among the most controversial – not least because he sided with the National Socialists in 1933. Based on brand-new sources, Lorenz Jäger paints a picture of the life of a philosopher who established an entirely new way of thinking about humans and their place in the world, starting with his Catholic childhood in Messkirch and the intellectual debates in the 1920s, moving on to the time under National Socialism, and far into the years of rebuilding after the war. We encounter teachers such as Edmund Husserl, whose teaching licence was revoked in 1936, confidants including Karl Jaspers and Hannah Arendt, whose intense if fraught relationship with Heidegger survived historical breaks, intellectuals and poets like Ernst Jünger and Paul Celan, who visited him in his hut in the Black Forest, and late interpreters of Heidegger’s life and work such as Lacan and Derrida. Lorenz Jäger’s biography shows how Heidegger triggers fascination and polarisation in every new generation and that his thinking has lost none of its relevance today – a masterful account both of the philosopher’s life and a German century.