The article takes as starting point an essay on civil friendship by Pedro Cerezo Galán in order to show the ethical and political relevance of friendship. Cerezo sheds new light on what could be called an ethics of friendship which goes back to ancient Greek philosophy. Drawing on Plato and Aristotle, the article discusses critically the concepts of ethos and of friendship in relation to the interpretations of Cerezo and Hannah Arendt and opens a new perspective on friendship as a way to self-knowledge.