A convention that organised much of the European theatre from the late nineteenth century into the middle twentieth — known, in the criticism of the period, as 'the fourth wall' — held that the stage represents a real room with the audience side removed, and that the actors are to behave as if no audience were present. The convention was not, when it appeared, a return to anything older; it was an explicit innovation, made possible by changes in lighting, stagecraft, and dramatic theory. It made possible a particular kind of psychological realism that the more rhetorical theatre of the early nineteenth century had not aimed at and could not have produced.
The innovation came with costs. To pretend the audience is absent is to impose on the dramatic action a continuity that the more theatrical traditions did not require. An actor in a Shakespeare play turns and addresses the audience; an actor in an Ibsen play does not, because to do so would break the fourth wall on which the play depends for its realism. The convention thereby narrows the range of what the play can do. It permits great psychological depth and pays for it in a certain inflexibility about the audience's place in the work.
The breaking of the fourth wall, when it came in the work of Brecht and after, was as deliberate as its erection had been. The Brechtian theatre did not abandon realism; it abandoned the convention that realism required the audience to be ignored. By speaking directly to the audience, by interrupting the action with songs that commented on it, by displaying the apparatus of the stage rather than concealing it, the new theatre asked the audience to think about what it was watching rather than to be absorbed into it. The asking was itself an artistic choice, with its own costs and gains.
What the history of the convention shows, and what is sometimes obscured in critical writing that takes either form as natural, is that neither the maintained fourth wall nor its deliberate breaking is the default condition of theatre. Both are conventions, each chosen for what it makes possible and at the cost of what it forecloses. To treat the fourth wall as the natural shape of dramatic art is to mistake one period's deliberate innovation for an underlying truth; to treat its breaking as a universal liberation is to make the same mistake from the other direction.
The primary purpose of the passage is to: