How does Marat/Sade contrast and complement the theories of theatre from Aristotle, Artaud, and Brecht?

Marat/Sade is a play about putting on plays in an insane asylum. While there is some history behind this premise, Peter Weiss’s play is more about the theatre itself and the power of theatre to transform audiences. Brecht and Artaud were two important  influences in Peter Brook’s famous staging of the play with the Royal Shakespeare Company in 1964.
Antonin Artaud was a surrealist who developed an approach to theatre called “The Theatre of Cruelty.” His premise was to subvert the conventions of theatre by encouraging a kind of “sensory overload” in the audience through the use of flashing lights, discordant sounds, inaudible or nonsensical dialog and so forth. This is meant to allow the audience to feel the unexpressed emotions of the subconscious.
Bertolt Brecht approached theatre as a way to indoctrinate or educate audiences about Marxist theories of labor and class struggle. Like Artaud, Brecht saw conventional theatre as suspect; however, while Artaud sought to give voice to the subconscious, Brecht subverted theatrical conventions in order to foreground their bourgeois nature and make a space for Marxist discourse. Brecht coined the term “Verfremdungseffekt” (alienation effect) for a series of strategies a playwright could use to subvert the audience’s desire to “believe” the story of the play. Music, for example, is not used to advance or enhance the story of the play but rather to break up the narrative flow and comment on the story.
Brook’s staging of Marat/Sade made use of both techniques. The play-within-a-play structure serves to reinforce the artificiality of the theatrical experience, while the frequent musical numbers serve to interrupt the action of the play. The character of Sade in particular enacts a kind of doubleness; he plays himself in the play-within-a-play, and his debates with Marat can be understood as a commentary on the history of Marat’s assassination as well as a commentary on staging plays in an insane asylum (or by the Royal Shakespeare Company, in the case of Brook). While much of the play is about the nature of “revolution,” the ending, in which the patients/actors are beaten into submission, calls into question whether such change is possible.