Canto serioso for French horn and piano was composed in connection with a competition taking place on 24 April 1913: The Royal Danish Orchestra had a vacant horn-player position. Nielsen must have composed the work during April after the competition was announced. In 1916, he re-arranged the work for cello and piano. The title, Canto serioso, emerged apparently long after Nielsen had completed the work. See more about this work at The Royal Library