Das Wohltemperierte Clavier I, Praeludium X

Description

A calm, singing first half and a rapid Presto second half split this E minor prelude cleanly in two, making it one of the most clearly two-part preludes in Book I of The Well-Tempered Clavier, where it is the tenth piece.

In the 4/4 first half, broken chords in left-hand sixteenths flow without pause while the right hand sings a freely ornamented melody above them. The second half switches to Presto, with both hands racing in quick sixteenths straight through to the end. The same kind of figuration that serves as accompaniment in the first half takes the lead in the second. Both halves stay between C2 and C6, which a 61-key keyboard covers.

Rated advanced, it lasts about 2 minutes 1 second with 1,143 notes in this data. The first half asks for balance, keeping the left-hand broken chords quiet while the right-hand melody sings; the second asks for secure fingers to keep both hands' sixteenths together at speed. Use the hand colours to see the roles of melody and accompaniment in the first half, and practise the Presto with slower playback and an A-B loop to section it off, and it can be finished without strain. Because the two halves ask for entirely different skills, the quickest route is to finish each separately and then join them.

Bach's collection of preludes and fugues for keyboard, covering all 24 keys and regarded as the summit of contrapuntal writing.