The form of this quartet evolves from and expounds features of a basic twelve-tone series. Babbitt makes his processes as intelligible as possible and leads his listener from one step to the next after all the possibilities have been investigated. The result is an exhilarating piece, self-contained and exact. And the beauty is not purely formal: there are many incidental pleasures in the springing deployment of string effects, as well as elegant changes of gear at the junctions between the four principal sections. (Paul Griffiths) The pitch material is developed gradually in the opening bars. An interval of a rising minor third predominates in bars 1–3, followed by a concentration on falling major thirds in bars 4–6. The following bars continue in this way, presenting a single interval or pair of intervals, beneath which groupings defined by dynamics and register develop patterns suggested by these intervals, eventually involving all aspects of the musical structure. The quartet alternates such sections of intervallic exposition with sections that develop the intervals presented up to that point, until eleven different ordered pitch-class intervals have been presented and developed until, in a moment referred to by Babbitt as "telling you the butler did it", the set that controls the entire musical structure is revealed by a process of "disambiguation", as Babbitt himself described it.