The Introduction sets out the questions at stake in the book. It argues that while practical political life is always guided by a pretheoretical understanding of politics, among theorists today there is no common agreement on the question of what politics actually is. The most illuminating response to this question has come from Hannah Arendt, but to fully grasp her response we have to do two things: to make explicit the understanding of politics implicit in her work; and to follow the way of thought by which she reached this understanding.