Of the nineteen compositions written between the 1936 Etude in a Classical Style for piano solo and the 1957 Music for String Orchestra, almost half (eight) are for voice and piano; all are relatively short in duration. Given the importance placed upon art song during his early career, the paucity of post-1957 vocal pieces in Kokkonen's oeuvre (roughly a quarter) is surprising—and especially given his life-long attraction towards poetry. In total there are only twelve vocal works (thirteen if the opera The Last Temptations is included); all but three are either for solo chorus, chorus with orchestra, or the singular work for soloist and orchestra, The Hades of the Birds. Further, aside from The Last Temptations, only the Hades of the Birds and the Requiem at all approach the rigor of such orchestral works as the four symphonies or chamber pieces such as three string quartets. In short, while vocal music remained a part of Kokkonen's mature works, his interest turned towards larger ensembles, and the more intimate vocal forms that occupied a central position in his early years as a composer clearly took a secondary role to his expanded canvases of instrumental music.