The Sonata for Two Pianos, eighteen in duration, is in the form of a large arch. The arch is constructed by relating the last movement to the second and first movements by borrowing material from these movements. The resulting form is a large ABA comprising the entire composition. The arch is superimposed over a more traditional formal concept of sonata. A sonata-allegro form is distinguishable in the first movement, a fantasia-variations in the second, and a modified sonata-allegro in the final movement.