By the time Joseph Haydn ( 1732- 1809) entered the lists, the Classical Era, with Vienna as its central field of action, was well established. Haydn and Mozart infused with genius the ideas of Emanuel Bach and the Mannheim symphonists, and gave definition to the period which found its culmination in Beethoven. That Haydn, Mozart, and Beethoven made the Austrian capital their home has given the title of Viennese Period to this most brilliant musical era. "It is impossible to overestimate the importance of music to the social and political changes which culminated in the decade of Revolution," says W. H. Hadow. "They meant that the old régime had been tried and found wanting; that the standard of taste was no longer an aristocratic privilege; that the doors of the salon should be thrown open, and that art should emerge into a larger and more liberal atmosphere."
Haydn was an ultramodernist in his day. When Albrechtsberger accused Mozart of breaking rules, Haydn retorted: "What is the good of such rules? Art is free, and should be fettered by no such mechanical regulations. The educated ear is the sole authority on all these questions, and I think I have as much right to lay down the law as any one." He gave concrete form and sanction to the sonata, string quartet, and the symphony. "It was from Haydn," Mozart claimed, "that I first learned the true way to compose quartets." Haydn was accused by his detractors of being a mountebank and of trying to found a new school! Among his definite innovations were: separating the opera sinfonia from the concert symphony; making a definite distinction between chamber and orchestral music; introducing a second theme in the exposition of the sonato-form; carrying the minuet over from the suite into the classical sonata, and making the rondo a dignified member of the sonata family.