In 1929 Piscator published his "The Political Theatre", discussions of the theory of theatre . In the preface to its 1963 edition, Piscator wrote that the book was "assembled in hectic sessions during rehearsals for "The Merchant of Berlin"" by Walter Mehring, which had opened on 6 September 1929 at the second Piscator-Bühne. It was intended to provide "a definitive explanation and elucidation of the basic facts of epic, i.e. political theatre", which at that time "was still meeting with widespread rejection and misapprehension."