Why do we always succumb to this bountiful, joyous, teary-eyed musical that melts even the cynical and leaves everyone singing? The glorious melodies of Rodgers and Hammerstein’s final show never age, and its plot never fails to touch us as it covers everything from music-making to resistance to tyranny. Documentary filmmaker Sara Lukinson, who teaches at New York University, traces how the story went from a German memoir and documentary to a Broadway hit, movie fame, and entertainment immortality.