Charles Rosen Quote
Some of the Etudes in the first set, opus 10, were written by the time Chopin was twenty. It is with these pieces that Chopin's style was fully revealed in all its power and subtlety. Later works are sometimes more ambitious and, in a few cases, more audacious, but there were no radical changes of style, nothing to compare to the later revolutions we find in the careers of Haydn and Beethoven, or even in the shorter lives of Mozart and Schubert. Chopin's mastery was proven with the twelve Etudes of opus 10.
Ch. 6 : Chopin: Virtuosity Transformed - The Romantic Generation (1995)