The Austrian composer Franz Joseph Haydn (1732-1809) essentially founded and brought to first mature realization the formal and structural principles of the classical style in his instrumental music, especially the symphonies and string quartets.

Joseph Haydn virtually created the classical formal structures of the string quartet and symphony, which were developed later by Wolfgang Amadeus Mozart and Ludwig van Beethoven. He participated in the development of other forms of 18th-century instrumental music, in addition to composing prolifically in the fields of sacred music, opera, and song. Throughout a lifetime of experimentation he developed in the quartet and symphony a fully mature classical tonal idiom, characterized externally by the four-movement structure (allegro, slow movement, minuet and trio, and finale) of the majority of these works and internally by emphasis on thematic and motivic development within a balanced tonal framework. Haydn evolved a tonal language that exhibited a gradual growth...