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").
Piano sonatas (Beethoven)
After he wrote his first 15 sonatas (up to Op. 28), he wrote to Wenzel Krumpholz, "From now on, I'm going to take a new path." Beethoven's sonatas from this period are very different from his earlier ones. His experimentation in modifications to the common sonata form of Haydn and Mozart became more daring, as did the depth of expression. Most Romantic period sonatas were highly influenced by those of Beethoven. After 1804, Beethoven ceased publishing sonatas in sets and only composed them as a single opus. It is unclear why he did so.