Hofmannsthal’s collaboration with another opera-composer than Strauss remained exceptional. In the 1920s, Wellesz composed an opera after a play written in the 1890s. This paper deals with the genesis of that work and describes the transformation of the play into a libretto. Wellesz and Hofmannsthal shared the belief that there was another way than Wagner’s conception of opera. However, the paradox is that the text of the opera no longer corresponds with Hofmannsthal’s conception of an opera libretto.