Prelude & Fugue No. 6 in D Minor

This is one of Bach’s chalk-and-cheese pairings: a busy-sounding Prelude which is actually low on musical incident, followed by an apparently modest Fugue packed with ingenious detail. The right hand of the Prelude is a virtually unbroken sequence of fast-flowing triplets (notes grouped in threes) outlining the shapes of chords. The key to the music’s architecture, though, is in the melodic phrases of the left hand, which calmly underpin the patterns above and plot out the harmonic direction. Halfway through, Bach begins building a slow climax, mostly over the home note of D in the bass, finally breaking free in a descending right-hand cascade silenced by four defiant chords. Bach builds an instantly recognizable “tag” into the theme of the Fugue: a trill, preceded by a shortened note, like a sudden intake of breath. This helps us keep tabs on its various adventures—including the first occasion in the Well-Tempered Clavier where Bach inverts the theme (turns it upside down). About J.S. Bach’s Well-Tempered Clavier Book I If we had to choose the most influential of Bach’s works in the centuries since his death, the biggest votes would probably go to the St. Matthew Passion and The Well-Tempered Clavier. The epithet “well-tempered” refers to “equal temperament”—a new method of tuning keyboard instruments, which made a wide range of keys available. Bach showed off these possibilities in two books of preludes and fugues in all 24 major and minor keys, which is why the collection is sometimes known as the “48.” Partly drawing on earlier works, Bach completed Book 1 around 1722, and Book 2 20 years later, constantly revising both. He intended the pieces to be useful to players of all types of keyboard instrument.