Ainsi la nuit (Thus the Night) is a string quartet written by the French composer Henri Dutilleux between 1973 and 1976.
Before starting to work on the piece, Dutilleux studied the string quartets of Beethoven and Bartók as well as Webern's Six Bagatelles.
He first wrote a series of preliminary studies titled Nuits (Nights),[3][8] some of which were sent to the Juilliard String Quartet in 1974.
[9] The piece is based on series of studies which focus on different aspects of sound production: pizzicatos, harmonics, dynamics, contrasts, opposition of register.
[10] Other techniques that are typical of Dutilleux can be found in the work such as fan-shaped phrases, a modal quality reminiscent of Gregorian chant as well as the highlighting of tonal triads in an atonal context.