Commissioned by the Calouste Gulbenkian Foundation, Tetras was composed in 1983 specifically with the Arditti Quartet in mind. Tetras signifies a group of four players of instruments, evoking the image of a string quartet: loud gestures, glissando passages, crunching noises, sudden starts, all of which are mixed with homophonic interruptions or serial counterpoint sequences. A multicoloured performance, containing a certain amount of humour, it manages to attain an intense expression of pure personal lyricism.
The premiere, given by the Arditti Quartet, took place in Lisbon on 8th June 1983.