Nocturnal was Edgard Varèse's last work, which was edited and completed by his former student, Chou Wen-chung. It was commissioned by and dedicated to the Koussevitzky Music Foundation. The work is scored for soprano, men's chorus, small orchestra, piano, an extended percussion section and two Ondes Martenots. The text includes phrases taken from Anaïs Nin's The House of Incest, as well as phonetic syllables of the composer's own devising. Dark and haunting, Nocturnal implies a tryst among siblings that captures the French novelist's alarming, mixed feelings towards unconventional and potentially damaging erotic scenarios.
The music derives some conventions from the Medieval Catholic church. Responsorial chant, the practice of alternating between a soloist and choir, is utilized to generate a perversely holy scenario. The evening union between brother and sister is clear, and the soprano clearly sings in first person while the male choir is ambiguous; its role is that of a standard chorus, commenting on the proceedings half in syllables and half in textual declarations of the dramatic impact the moment is generating. Nin's ability to make even horrifying sexual situations seem adventurous for the subject (herself) is coupled with a tone of sacrifice. This sort of writing works admirably with Varèse's understanding of nature as an uncontrollable force; both siblings are in the grip of improper desires, but the power of youthful, erotic energy is illustrated here with a largeness of emotional scope that is a testament to human vitality's propensity for spinning out of morality's orbit. Nothing is condoned in the music; Nocturnal combines the brother and sister's situation with that of the surrender of Christ; incest is a betrayal just as Christ was betrayed, who begged for the forgiveness for all who had betrayed him. No blame is assigned and no coercion is implied.
Nocturnal was composed for a Composers' Showcase concert in his honor. Its premiere took place at the Town Hall in New York on May 1, 1961, with Robert Craft conducting. It is the one work of Varèse's that did not "crystallize," which is how he described music that was finished to his satisfaction. Illness and indecision kept him from finishing the job. The score for the first performance had been completed only two days before the premiere, and there was only one rehearsal, except that Carlos Salzedo had done some preliminary work with the chorus. The following autumn, the composer went to work on a second version of the piece and it is difficult to discern drafts from the second version, Nocturnal II, from revisions of the first work. To make matters more difficult for historians, Varèse then began another work, Night, for a near-identical ensemble and more excerpts from Nin's The House of Incest. This work never neared completion.