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 «Lehrstücke», 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.