Beethoven is viewed as a transitional figure between the Classical and Romantic eras of musical history. Above all, his works distinguish themselves from those of any prior composer through his creation of large, extended architectonic structures characterized by the extensive development of musical material, themes, and motifs, usually by means of "modulation", that is, a change in the feeling of the home key, through a variety of keys or harmonic regions. Although Haydn's later works often showed a greater fluidity between distant keys, Beethoven's innovation was the ability to rapidly establish a solidity in juxtaposing different keys and unexpected notes to join them. This expanded harmonic realm creates a sense of a vast musical and experiential space through which the music moves, and the development of musical material creates a sense of unfolding drama in this space. In this way Beethoven's music parallels the simultaneous development of the novel in literature, a literary form focused on the life drama and development of one or more individuals through complex life circumstances, and of contemporaneous German idealism's philosophical notion of self, mind, or spirit that unfolds through a complex process of contradictions and tensions between the subjective and objective until a resolution or synthesis occurs in which all of these contradictions and developmental phases have been resolved or encompassed in a higher unity.
Beethoven continued to expand the "development" section of works, extending a trend in the works of Haydn and Mozart, who had dramatically expanded both the length and substance of instrumental music. As Beethoven's major immediate predecessors and influences, he looked to their harmonic and formal models for his own works. However, both Mozart and Haydn placed the great weight of a musical movement in the statement of ideas called the exposition, for Beethoven the development section of a sonata form