28: Variation 19
27: Variation 8
Variation 19 (8:40) is a nostalgic break in the action from the charming, echoic canon on the sixth and the bustling, energetic variation 20. Two distinct motives are shared between the three voices throughout: a six-note sixteenths figure, and a syncopated eighth-note/quarter note figure. The genius here is in the tied notes that are suspended over the bar lines; these held notes give the variation its unique rhythmic and harmonic character. Beautiful indeed!
Variation 8, like variation 19, has two main ideas which are repeated measure by measure and passed between two voices. In the first four measures, the top voice plays rising arpeggiated sixteenths (with one sixteenth note "missing" at the end of each bar), while the bass plays four falling eighth notes, followed by three falling sixteenths. In the second phraselet (bars 5-8), both parts are inverted, or turned upside down. This is a common technique Bach uses, especially in GBV, to change things up within a variation while maintaining its rhythmic character and give the listener something to latch onto (it happens to a greater or lesser extent in variations 1, 5, 11-17, 20-21, 23, and 26-28 aka all over the place). Variation 8 is a doozy for pianists; look what GG has to do in the last measure (0:50)! Gah!