Of Johann Sebastian Bach’s twenty children, three were outstanding musicians in their own right. Of these three – Wilhelm Friedmann, Johann Christian and Carl Philipp Emanuel – the last was the most influential as a composer, creating a bridge between the exuberant Baroque style of his father and the Classical style of Haydn and Mozart. While always acknowledging a great debt to his father (his only teacher), he eventually came to reject the complexity of polyphonic music, preferring a much more subjective and dramatic approach, full of unexpected and odd shifts in harmony, and with an emphasis on melody – a style known as empfindsamer Stil (expressive style).
Although C.P.E. Bach’s educational background was broader than his father’s – he trained as a lawyer and preferred the company of writers and intellectuals to that of musicians – he suffered a similar hard grind as a musician: in his case nearly thirty badly paid years as a keyboard player at the court of Frederick the Great at Potsdam. Frederick’s taste was conservative, and the experimental nature of much of C.P.E. Bach’s music meant that he never won preferment – indeed his principal duty seems to have been to accompany Frederick, a keen amateur flautist, on the harpsichord. Perhaps it was to widen his fame outside the narrow confines of Potsdam that he published his Essay on the True Art of Playing Keyboard Instruments, a highly influential treatise which was used as a teaching aid by both Mozart and Beethoven. In 1767, upon the death of his godfather, Georg-Philipp Telemann, the restless C.P.E. Bach succeeded him as music director of the five principal churches in Hamburg. His workload was enormous but, away from his church duties, the freer atmosphere of the commercial city-state made the last twenty years of his life much more stimulating.
from ROUGH GUIDE TO CLASSICAL MUSIC by JONATHAN BUCKLEY, PHILIP CLARK, et al. http://roughguides.com