downbeat of m. 5) contains a more robust bass motion: from D to B-flat, to G, to A, then back to D. This fundamental bass line, associated with the theme, serves as the basis for a number of the variations, and it returns with the theme at structurally important moments throughout the movement.Before we listen to the Chaconne, let’s sample a couple of the bass line variations that Bach uses. In mm. 21-25we can hear a descending chromatic linein the bass, moving down by semitone from tonic to dominant.The two-voice textures in mm. 22and 23suggest fuller harmonies. But part of the power of such passages is the ability of so few notes to convey so much, without having to be explicit.Chromaticism throughout the Chaconne is a marvel in itself, as we’ll hear. The chromatic “filling in” of the descending bass line is just one aspect of this chromaticism, but an important one. Let’s listen to the notes of mm.
21-25A number of Bach’s variations make use ofsequences.Not surprisingly, some of these are of the “fallingfifths” variety, the most frequently occurring sequence in tonal music.Let’s listen to the notes of mm.57-61, followed by a “sorting out” of the strongly implied harmonies, with accompanying Romannumerals.Observe that Bach’s falling fifths sequence moves through the entire diatonic circle of fifths, using every note of the diatonic D minor scale as the root of a diatonic triad:The roots of these chords are as follows: D – G – C – F – Bb – E – A – DThe Roman numerals for each chord are: i – iv – VII– III– VI- ii° - V – i And the sequence is melodic, as well as harmonic. Recall that two descending fifths “equal” a descending second, and notice that all the notes of m. 57are repeated a step lower in m.58, and another step lower in m. 59, using the notes of the diatonic scale. This is the hallmark of a descending fifths sequence(a. k. a., “falling fifths” sequence); that is, a diatonic transpositionof harmonic and motivic material by successive downward scale steps..