Alienation (Vefremdung) is a concept inextricably linked with the name of twentieth-century German playwright Bertolt Brecht — with modernism, the avant-garde and Marxist theory. However, as Phoebe von Held argues in this book, ‘alienation’ as a sociological and aesthetic notion avant la lettre had already surfaced in the thought of eighteenth-century French philosopher and writer Denis Diderot. This original study destabilizes the conventional understanding of alienation through a reading of Le Paradoxe sur le comedien, Le Neveu de Rameau and other works by Diderot, opening up new ways of interpretation and aesthetic practices. If alienation constitutes a historical development for the Marxist Brecht, for Diderot it defines an existential condition. Brecht uses the alienation-effect to undermine a form of naturalism based on subjectivity, identification and illusion; Diderot, by contrast, plunges the spectator into identification and illusion, to produce an aesthetic of theatricality that is profoundly alienating and yet remains anchored in subjectivity.