Inventions In 2 Voices, Sinfonias In 3 Voices, Bwv 772-801

Bach conceived his Inventions and Sinfonias as short works meant to
help his son Wilhelm Friedemann and various pupils master keyboard
practice. The 1720 Edition used by pianist Nagano attempts to create
a fluid, organic unity of purpose to the collection. Each piece sets a problem of its own: each adds sharps in order of difficultly, in keys ascending and descending. Each dance maintains a distinct sense of counterpoint, often energized, as in No. 3 in D, but sometimes plaintive and chorale-like, as in Invention No. 9 in F Minor. No. 1 in C Major exploits the interval of a fourth that plays against itself. No. 2 in C Minor approaches an orchestral sound. The longest Invention, No. 6 in E Major, weaves a chorale in the midst of interweaving chromatic lines.

The Sinfonias, too, begin with C Major and proceed to the distant B Minor. Bach employs only 15 of the 24 keys in the chromatic scale. No. 7 in E Minor has a tragic aspect, much in the manner of chorale. The difference from the Inventions lies in Bach’s application of the bass line, which in the Sinfonias accompanies the upper voice at the beginning. The No. 9 in F Minor uses the B-A-C-H motif, opening transposed as A-flat-G-B-flat-A, a tragic, austere piece. No. 15 uses crossed-hand technique in 16th notes with staccato accents, a florid, pearly effect.