The Quartet has a formal intricacy that fascinates analysts but is completely lost on the ordinary listener. It has been characterized as an "arch," as two sonatas superimposed on each other, and, perhaps most helpfully, as a sonata with a slow movement inserted between the development and recapitulation. In the introduction (marked andante alla marcia), the oboe stays aloof from the strings, singing while they march. A quicker section follows in which themes are introduced and developed. Where the recapitulation would normally arrive to reestablish familiar material, Britten instead has something completely different in both music and instrumentation: a slow section without the oboe. When it finally gets around to recapitulation, the music returns in a mirror image of the way it first arrived: first the quick exposition, then the opening slow march. At the last, the lone cello repeats the first seven bars of the piece, in reverse order.