technique. Wolfgang Amadeus Mozart applied the large-scale ideas of Haydn to opera and the piano concerto. Mozart's fluidity with the creation of themes, and the dense network of motives and their parts give his work a surface polish which was remarked upon even by his professional rivals. Mozart favored sonata form and the sonata cycle. Most of his compositions were in sonata cycle. He explored every genre of his day and perfected them all. By the end of his short life, Mozart had absorbed Haydn's technique and applied it to his own more elongated sense of theme, for example in the Prague Symphony. Romantic period (ca 1825 – ca 1910) Ludwig van Beethoven was the composer who most directly inspired the theorists who codified sonata form as a particular practice. While he was grounded in the fluid phrase structures and wider variety of possible schematic layouts that came from Haydn and Mozart, his deepest innovation was to work from both ends of a sonata form, conceiving of the entire structure, and then polishing themes which would support that overarching design. He continued to expand the length and weight of the sonata forms used by Haydn and Mozart, as well as frequently using motives and harmonic models drawn from the two older composers. He shares both the Classical and Romantic eras. Because of his use of increasingly characteristic rhythms and disruptive devices, he is seen as a transitional figure between the Classical and Romantic periods. In the Romantic era, sonata form was first explicitly defined and became institutionalized. Academic scholars like Adolph Bernhard Marx wrote descriptions of the form, often with a normative goal; that is, a goal of stating how works in sonata form should be composed. While the first-movement form had been the subject of theoretical works, it was seen as the pinnacle of musical technique. Part of the training of 19th-century composers was to write in sonata form and to favor sonata form in the first movement of multi-movement compositions, like symphonies, piano concertos, and string quartets. The 19th century's procedure for writing sonatas diverged from earlier Classical practice, in that it focused more on themes than on the placement of cadences. The monothematic exposition (a common characteristic of Haydn's sonata-form movements) largely disappeared, and the themes of the first and second groups were expected to contrast in character. More generally, the formal outline of a sonata came