Alongside Wieland Wagner, Walter Felsenstein (1901-1975) was the most important opera director of the early post-war period in Germany. To this day, the dramaturgic preparation of his productions at the Komische Oper in East Berlin can justly claim exemplary status. With despotic thoroughness he subjected the works of the operatic canon to his ideal of strict causality in the development of the plots. With reference to central productions and drawing upon copious production notes, adaptations, and scenarios, this appreciation sets out to reconstruct Felsenstein's concept of 'realistic music theatre' without glossing over the internal contradictions that it displayed.