Eugen Berthold Friedrich Brecht (10 February 1898 – 14 August 1956), known professionally as Bertolt Brecht, was a German theatre practitioner, playwright, and poet. Coming of age during the Weimar Republic, he had his first successes as a playwright in Munich and moved to Berlin in 1924, where he wrote The Threepenny Opera with Kurt Weill and began a life-long collaboration with the composer Hanns Eisler. Immersed in Marxist thought during this period, he wrote didactic Lehrstücke and became a leading theoretician of epic theatre (which he later preferred to call "dialectical theatre") and the Verfremdungseffekt.