Carl Philipp Emanuel Bach (8 March 1714–14 December 1788) was a German musician and composer. He was the second of five sons of Johann Sebastian Bach and Maria Barbara Bach. He was said to be one of the greatest harpsichord players of his time. He wrote a book called "Essay on the True Art of Playing Keyboard Instruments" (1755), which was used by Mozart, Haydn and Beethoven. 