From the liner notes:
My string quartet no. 3 (1971), commissioned by The Julliard School for the Julliard String Quartet, divides the instruments into pairs: a Duo for Violin and Cello that plays in rubato style and one for Violin and Viola in more regular rhythm.
The violin-Cello Duo presents four different musical characters: an angry, intense Furioso, a fanciful Leggerissimo, a Pizzicato giocoso and a lyrical Andante expressivo, in short sections one after the other in various orders, sometimes with pauses between. The Violin-Viola Duo, meanwhile, presents the six contrasting character listed in the program. During the Quartet each character of each Duo is presented alone and also in combination with each character of the other Duo to give a sense of ever-varying perspectives of feelings, expression, rivalry and cooperation.