"What Keeps Mankind Alive?" is a song composed by Kurt Weill with lyrics by Bertolt Brecht for their drama with music The Threepenny Opera which premiered in Berlin in 1928 at the Theater am Schiffbauerdamm. The title refers to the central line from the finale of act 2, Denn wovon lebt der Mensch?. In the play, the two stanzas of the strophic piece are sung by Macheath and Low-Dive Jenny and the final line is sung in fortissimo by the chorus.