O'Brien takes seriously Heidegger's claim in the Letter on Humanism that thinking needs what he calls an originary ethics, and argues that the phrase becomes intelligible only through Heidegger's account of what a human being is. On that account we are finite, thrown, placed creatures who find ourselves already inside a language, a landscape and an inherited set of customs; ethos names dwelling before it names a code of conduct. The argument runs through the Bremen lectures, where Heidegger's notorious sentences on death camps and mechanised agriculture are read as part of a claim that modern technology flattens nearness and endangers the dwelling that ethics depends on. O'Brien then answers critics who say this leaves only relativism, or the ethnic chauvinism Heidegger embraced in the 1930s, proposing that shared finitude and shared placedness bind communities to one another. Autobiographical passages from rural Ireland carry much of the demonstration.