While in Berlin, Bach placed himself in the forefront of European music with a treatise, "" ("An Essay on the True Art of Playing Keyboard Instruments"), immediately recognised as a definitive work on keyboard technique. "Both Haydn and Beethoven swore by it." By 1780, the book was in its third edition and laid the foundation for the keyboard methods of Clementi and Cramer. The essay lays out the fingering for each chord and some chord sequences. Bach's techniques continue to be employed today. The first part of the "Essay" contains a chapter explaining the various embellishments in work of the period, e.g., trills, turns, mordents, etc. The second part presents Bach's ideas on the art of figured bass and counterpoint, as well as performance suggestions and a brief section on extemporization, mainly focusing on the Fantasia.