Henri Dutilleux's work for string quartet, Ainsi la nuit (1976) was commissioned by the Koussevitzky Foundation and was intended for performance by the Juilliard Quartet. Before starting on the actual composition, Dutilleux spent some time studying the intricacies of string-playing techniques of the time. He had not attempted to write a work for string quartet since his days as a student at the Paris Conservatoire. The composer has stated that Webern's Six Bagatelles (1913) were most beneficial in helping him get up to date. Dutilleux also looked over Berg's Lyric Suite (1926), as well as compositions for string quartet by Beethoven and Bartók. After making a series of sketches in which he practiced writing for string quartet, the composer sent three completed pieces to the Juilliard Quartet. These pieces, entitled Nuits (1974), have musical material which was later used in the final version of Ainsi la nuit. Dutilleux completed Ainsi la nuit in 1976 and the work was premiered on January 6, 1977, in Paris, but not by the Juilliard Quartet. Actually, the premiere was given by the Quatuor Parrenin. The Juilliard Quartet would first perform the composition in the Library of Congress at Washington, D.C., on April 13, 1978.
The final version of the piece has seven movements with four "parentheses" lying in between the first five movements. Dutilleux did not like to leave the individual movements of his works untitled. The seven movements of Ainsi la nuit are "Nocturne I," "Miroir d'espace," "Litanies I," "Litanies II," "Constellations," "Nocturne II," and "Temps suspendu." The "parentheses" are mostly used to recall or foreshadow musical material in the rest of the work. For this reason, Ainsi la nuit is often associated with the idea of memory.
Many of the characteristics of Dutilleux's later works are displayed in Ainsi la nuit, including "fan-shaped" writing, the outlining of a tonal triad in a seemingly atonal work, and a similarity of some melodies to the modality of Gregorian chant. Dutilleux's "fan-shaped" writing can best be described through a piano composition in which the placement of the pianist's fingers create a mirror image between the hands. In Ainsi la nuit, this is accomplished through the voices of the four string instruments. Many of Dutilleux's pieces from the same period as Ainsi la nuit also make use of "fan-shaped" writing. It has also been discovered that in some of Dutilleux's later works, a tonal triad is outlined over the course of the piece by an emphasis on individual pitches. This is also true in Ainsi la nuit, as a D major triad is outlined with each successive pitch being centered upon in a separate movement. The pitch D is emphasized in the untitled introduction, while F sharp is the most important pitch in the fourth movement, "Litanies II." Finally, in "Constellations," the climax of the piece, the pitch A is the central pitch. The Gregorian influences in "Nocturne I," as well as the opening of "Litanies II," were acknowledged in Dutilleux's own program note.