|The development section of a sonata allegro allows the composer to demonstrate his creativity by manipulating material presented in the exposition. To this end, the composer will frequently utilize harmonic tension and free use of counterpoint to elaborate stated material.
In a typical Mozart symphony or even Beethoven's first two symphonies, the development would comprise about 50 measures. The Eroica's development section is 242 measures. This audacious expansion permitted Beethoven to showcase his genius for motivic development.