 Well, when Louis Armstrong and Ella Fitzgerald and Bobby Darin sang Mac the Knife, it was not quite the same song that Kurt Weill and Bertolt Brecht wrote in Berlin in 1928. And that wasn't quite the same song that Americans first heard in the off-Broadway hit play Three Penny Opera in 1954. Before we listen to some different versions of Mac the Knife, tell us about the origins of song and about the character of Mac.