Beethoven's musical style
The compositions that Beethoven wrote in his formative period can be generally characterized by the composer's efforts to master the predominant classical language of the period. His works from this period can be subdivided into two, based on the composer's residence. First, various juvenalia, written when the adolescent Beethoven was in residence in Bonn and heavily indebted to the works of contemporaries, especially Mozart and his teacher, Christian Gottlob Neefe. These early efforts can be seen in a set of three piano sonatas and piano quartets (WoO 36) that Beethoven wrote before 1792. The Quartets, for instance, are each specifically modelled after three Violin sonatas Mozart published in 1781 – K 296, 379 and 380 – and Beethoven would later draw upon this familiarity in the composition of several of his own Violin Sonatas.
Beethoven's musical style
Beethoven's musical output has traditionally been divided into three periods, a classification that dates to the first years after the composer's death in 1827 and was formalised with the publication of Wilhelm von Lenz's influential work "Beethoven et ses trois styles" (Beethoven and his Three Styles). Lenz proposed that Beethoven's creative output be marked by three periods of distinct stylistic personality and he identified specific compositions as milestones for each period. In Lenz's work, the first period opens with Beethoven's Trio set, Opus 1 and culminates with the performances in 1800 of his first symphony and Septet. The second period spans the period from the publication of his Moonlight Sonata to the Piano Sonata in E minor, Op. 90 in 1814. The last period covers Beethoven's mature works to his death in 1827.