Il canto sospeso established Nono as one of the leading composers of the European post-war avant garde. Originally composed for the Darmstadt summer courses of 1956, its completion was delayed, and at the initiative of Hermann Scherchen, the commission was "re-directed" so that the first performance, which Scherchen conducted himself, could take place on the premises of the Westdeutscher Rundfunk in Cologne on October 24, 1956. The text for Il canto sospeso, which can be variously translated as "the suspended song," "the interrupted song," or "the song unsung," was taken from an anthology of letters written by captured European resistance fighters prior to their execution by the Nazis. The anthology was first published in Italian in 1954; a German translation was published in the following year with a foreword by Thomas Mann.

Dimitri Mitropoulos was Greece’s most prolific conductor and New York Philharmonic Music Director from 1949-1958.  Widely regarded as one of the most significant conductors of the twentieth century, he is best remembered for his significant recorded legacy and for his commitment in bringing new compositions to the stage of major symphony orchestras.  Indeed, it is thanks to his efforts that many of our current symphonic standards made their way into the repertory.  He gave World and American premiers of seminal works such as Gustav Mahler’s Symphony No. 6 and Schoenberg’s Erwartung, as well as other major works by Schoenberg, Shostakovich, Prokofiev, and many others.  His personal collection has been held in private hands since his death in 1960, when it passed to conductor James Dixon, his student and protégé.  Mitropoulos came to consider Dixon his son, introducing him to conductors and performing arts institutions around the world, jumpstarting his career.  When Mitropoulos died in 1960 he left all his belongings, including his scores, to Dixon.  The bulk of the musical library has been subsequently gifted to the University of Iowa’s music library, but a selection of rare items have been selected to be offered for sale exclusively by Schubertiade Music & Arts.  These examples, many inscribed to the conductor from composers or associates, have only occasional markings from the conductor himself who committed all music to memory before his first rehearsal of the repertoire - a highly unusual method!  Some of these scores, however, were also subsequently used by James Dixon as part of his working reference library for many years and include his occasional markings.