Carter conceived it as "a piano piece of continuously changing moods, suggesting the fleeting thoughts and feelings that pass through the mind during a period of wakefulness at night."
The composer further described the form of the work in the score program note, remarking:The quiet, nocturnal evocation with which it begins and to which it returns occasionally, is suddenly broken by a flighty series of short phrases that emerge and disappear.
The pianist Charles Rosen, who co-commissioned the piece, described it as "perhaps the most extraordinary large keyboard work written since the death of Ravel.
"[2] The music critic Mark Swed of the Los Angeles Times called the work "an unforgettable memory" and observed, "Its complexities alone could keep you up at night.
"[2] Jerry Kuderna of the San Francisco Classical Voice similarly described it as Carter's "magnum opus for piano.