It is a commonplace that the poetry best suited to an operatic libretto has fewer pretensions, and more transparency in the range of interpretations that can be placed upon it, than ‘literary’ poetry. Otherwise, it will scarcely bear the weight of the music, much less contribute to the great emotional climaxes that justify opera for many listeners in the first place. And some might mistrust a libretto that is too ‘literary’ or too complicated, for metaphysical and other subtleties are not easily projected across the footlights. No one was more acutely aware of this ‘unliterary’ relationship between words and music in opera than W. H. Auden. Writing in 1948, he stated: ‘Poetry is in its essence an act of reflection, of refusing to be content with the interjections of immediate emotion in order to understand the nature of what is felt. Since music is in essence immediate, it follows that the words of a song cannot be poetry.’