“But for the opera I could never have written Leaves of Grass. […] My younger life was so saturated with the emotions, raptures, uplifts, of such musical experiences that it would be surprising indeed if all my future work had not been covered by them. A real musician running through Leaves of Grass – a philosopher musician – could put his finger on this and that anywhere in the text no doubt as indicating the activity of the influences I have spoken of.“

Walt Whitman