This book started from an intense reading in the work of Walter Benjamin and the interest I took in one recurring reference in his writings—the texts of the anti-Semite Ludwig Klages (1872–1956). Behind this relatively unknown figure (to twenty-first-century readers), I found a whole network of references to a philosophical movement known at the time as the philosophy of life (Lebensphilosophie), and I discovered that Klages was one of its outspoken representatives. This turn-of-the-century movement bloomed during the 1920s and was later integrated into the Nazi rhetoric as biopolitics. Biopolitics will be understood here in the most general sense, characterized by Roberto Esposito as that in which "life becomes encamped in the center of every political procedure,"¹ a definition closest to the Nazi use of the concept in 1932. As a Nazi discourse, it disappeared after the Second World War, to be revived in the past ten years in a very different cloth. This book traces the origins of this discourse of life, its politicization, Nazification, and later transformation. In so doing, I make a plea of relevance to everyone interested in the rise of Nazi biopolitics, but more than that, to everyone interested in the radical critique of biopolitics, as shown in Walter Benjamin's writings and by recent critics of democracy from the left—for example, Giorgio Agamben, Roberto Esposito, Michael Hardt, and Antonio Negri—who adapted Benjamin's reflections to our present-day reality.