Gray, the first musicologist to write on the piece's structure, makes no mention of sonata form, yet refers to the existence of two different subjects, seeming to imply that the movement is in sonata form. Abraham is one of the first to analyse the work in terms of sonata form and clearly lays out where he believes each section begins and why. He shows that the work opens with a double exposition, each with distinct A- and B-group material, then moves into the development of this material. He explains the distinctly melodic section beginning at the "Allegro moderato" as a Scherzo and Trio used as a substitute for the second half of the development. Layton disagrees with Abraham and considers the Scherzo to be the beginning of the recapitulation.