Piano sonatas (Beethoven)
Ludwig van Beethoven wrote his 32 piano sonatas between 1795 and 1822. Although originally not intended to be a meaningful whole, as a set they compose one of the most important collections of works in the history of music. Hans von Bülow called them "The New Testament" of the piano literature (Johann Sebastian Bach's "The Well-Tempered Clavier" being "The Old Testament").
Leopold Koželuch
Koželuch's substantial output of keyboard compositions reflected the promotion of his reputation as a specialist keyboard virtuoso. Christopher Hogwood argues that Koželuch's keyboard sonatas, especially those which open in minor keys, "substantially anticipated ... the tragic-pathetic manner" of Beethoven and Schubert, and that in them he "created the internationally praised "cantabile" idiom". Hogwood further states that "Koželuch's sonatas are, in the true sense, 'classics'—that is to say, 'models for imitation and study'—and display to perfection precisely those features that theorists required of a sonata at the end of the 18th century. The oeuvre of sonatas spans almost the entirety of Koželuch's career: the first was composed in 1773; the final three date from after 1810. The sonatas cater for different purposes. Some are exhibitionist works; some are simpler; some are cast in a Romantic style that foreshadows Beethoven. In the third category, Koželuch was composing slow minor-key introductions to sonatas as much as 17 years before Beethoven composed his Piano Sonata No. 8 ("Pathetique"), while neither Mozart nor Haydn ever did so. Koželuch's composed his sonatas to be played on the newly emerging fortepiano rather than the harpsichord. The popularity of the sonatas in turn helped to make the fortepiano fashionable.