This chapter focuses on a song and drama rather than about opera specifically. Opera is particularly interesting because it can be seen as the extreme form of musical drama, and so the problems of song and drama come out most sharply. In Levinson's Song and Music Drama, he treats operas as, in effect, long songs, with the problem of fit between musical and non-musical elements being the same in both, although more difficult in musical drama. Like a good song, a good music drama is one that provides audiences with a good experience, rather than one that displays the correct relationship between words and music. And while a good libretto contributes to some of the operas that provide such an experience, a good libretto seems neither necessary nor sufficient to a good music drama. In some dramatic productions, singing happens as a natural part of the plot. Singing can serve a variety of functions within a single dramatic production.