It is a sonata for viola solo in six movements, and Ligeti composed it in various phases, parallel with his Violin Concerto, and his piano études.

This perhaps harks back to Frescobaldi's sonatas where one can find a Toccata Cromatica as well as examples of the passacaglia and chaconne.

[2] Critic Blair Sanderson referred to the sonata as "one of the major viola works of the 20th century".

[10] The technical difficulty is remarkable, the double stops always include one open string and involve wide jumps between different positions that are rather challenging for the left hand.

The difficulty and intensity increase gradually and propel the musical argument towards an interrupted finale.

[9] The Facsar shows the emphasis on the rhythm of the second movement with the melodic and harmonic language, with a constant transformation of the thematic material in all ways possible.

[12] In the fourth movement, Ligeti employs combinations of accents, highly contrasted dynamics such as ff followed one quaver later by pp, adjacent notes or very close intervals, open strings, double stops and harmonics, all played 'as fast as possible'.

The effect is original and disquieting but does not require highly dissonant or chromatic writing to make its impact [13] In the subsequent occurrences of the thematic material, the composer makes changes through addition or subtraction of notes, transforming individual notes in chords and vice versa, and consequently adapting the accentuation and dynamics.

This last movement takes up and amplifies the ternary form of the subject in the previous Lamento, with a theme (mm.

The underlying idea is a chromatically descending cantus firmus, which is preserved in most of the repetitions, with minor alterations.

In the latter section, the music intensifies and the climax is interrupted in bar 80 with the tempo marking Meno mosso, molto cantabile, ending quietly.