Kurt Weill wrote to UE in 1927, during his work on Mahagonny:

It is beyond question that at present a completely new kind of stage work is emerging, which addresses itself to a different and incomparably larger audience, and whose effect will proliferate in completely unaccustomed ways. This movement – whose most powerful proponent, in the field of theatre, is Brecht – has until now never encroached upon opera, even though music is one of its essential elements. The piece that we plan to write will not exploit contemporary events that will be obsolete in a year’s time, but give our own time a definitive form. Thus its effectiveness will extend far beyond the time of its creation. It is indeed a matter of creating the new genre that will deal with the utterly different expressions of life in our time in an appropriate form.