Brecht's theory and practice of theatre changed considerably during his career. In particular, once he had adopted a Marxist view of society (towards the end of the 1920s) Brecht began to develop a conception of theatre that would propagate that view of society and thus help to bring about fundamental social change. This essay will first outline the main principles of Brecht's theory before going on to examine the relationship between his declared intentions and his practice as a writer and producer of plays.