. Fr. développement; Ger. Durchführung, i.e. ‘through‐leading’; It. svolgimento, i.e. ‘unfolding’)
The treatment of the detailed phrases and motifs of a previously heard theme (‘subject’) in such a way as to make new passages, often of a modulatory nature. The second section of sonata form, coming between exposition and recapitulation, is the development. With the expansion of the symphony, the development section became increasingly complex and important. Beethoven departs from convention in his 3rd sym. by introducing new thematic material in this section. There is also a development in fugue.