The author attempts to demonstrate a dialectic development in Brecht’s work, form the self-destructive nihilism of the early work, which finds its culmination in the opera Mahagonny, through the crisis of identity in the early Lehrstuecke, which shows itself, above all, in the conflict between Baal, the alter ego of the younger Brecht, and Keuner, who fulfils a similar function in the later work, to the second optimism of the last plays and poems.