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Sonata idea or principle

Research into the practice and meaning of sonata form, style, and structure has been the motivation for important theoretical works by Heinrich Schenker, Arnold Schoenberg, and Charles Rosen among others; and the pedagogy of music continued to rest on an understanding and application of the rules of sonata form as almost two centuries of development in practice and theory had codified it.

The development of the classical style and its norms of composition formed the basis for much of the music theory of the 19th and 20th centuries. As an overarching formal principle, sonata was accorded the same central status as Baroque fugue; generations of composers, instrumentalists, and audiences were guided by this understanding of sonata as an enduring and dominant principle in Western music. The sonata idea begins before the term had taken on its present importance, along with the evolution of the Classical period's changing norms. The reasons for these changes, and how they relate to the evolving sense of a new formal order in music, is a matter to which research is devoted. Some common factors which were pointed to include: the shift of focus from vocal music to instrumental music; changes in performance practice, including the loss of the continuo.

Crucial to most interpretations of the sonata form is the idea of a tonal center; and, as the Grove Concise Dictionary of Music puts it: "The main form of the group embodying the 'sonata principle', the most important principle of musical structure from the Classical period to the 20th century: that material first stated in a complementary key be restated in the home key".(

The sonata idea has been thoroughly explored by William Newman in his monumental three-volume work Sonata in the Classic Era (A History of the Sonata Idea), begun in the 1950s and published in what has become the standard edition of all three volumes in 1972.