the first movement begins with the solo piano unfurling a series of virtuosic pronouncements punctuated by emphatic loud chords from the full orchestra. the vigorous, incessantly propulsive main theme follows, undergoing complex thematic transformation, with a secondary theme of tonic and dominant notes and chords. when the piano enters with the first theme, the expository material is repeated with variations, virtuoso figurations, and modified harmonies. the second theme enters in the unusual key of b minor before moving to b major and at last to the expected key of b major several bars later.