The most widely known of Kurt Weill's songs, such as the satirical operas he wrote with Bertolt Brecht, often appear shorn of their original context. Yet, even when warmed by the heat of Louis Armstrong (“Mack the Knife”), the cold brutality of street life is still palpable. Weill's early melodies are unvarnished and eerie, often best suited to a lone voice and the sparse accompaniment of a tinkling piano or a modest chamber ensemble. After fleeing Nazi Germany to start again in New York, a welcome sentimentality had entered his work, particularly the swooning “September Song” and the 1946 jazzy, observational opera Street Scene.