Beethoven is considered to be one of the greatest masters of
musical construction.
He was one of the first composers
to systematically and consistently use interlocking thematic devices, to achieve inter-movement unity in long compositions.
Beethoven composed in a great variety of genres, including symphonies, concerti, piano
sonatas, other sonatas (including for violin), string quartets and other chamber music, masses, an opera, lieder, and various other genres.
He is viewed as one of the most important transitional figures between the Classical and Romantic eras of
musical history.
As far as I know, Beethoven worked from the principles of sonata form and motivic development that he had inherited from Mozart and Haydn.