I would guess that the vast majority of classical musicians have no idea what they are playing and how each composition works. Some might recognize the key, and see scalar or arpeggiated passages. But it is difficult enough for anyone just to learn many of these pieces! In other words, performers need to focus on developing the technical facility by learning the various etudes, scales, arpeggios and related techniques. Baroque improvisation, which was once prevalent has pretty much disappeared in current times, although a rare few are continuing the artform.
So it was a pleasant surprise to find this harmonic analysis of Bach’s Minuet in G. Even though it’s a fairly simple tune, you can learn a lot by understanding the chord progression and which melody notes were used over each chord. Note the chord names added to this score. Look at the bass notes and the melody notes and how they outline each chord.
Note that the bass notes (in bass clef) are usually chord tones, but not always the root. Other chord tones are used for smooth bass line movement and voice leading concepts. Also note the I IV and I V movement which are very common.
In the second half of the piece (page 2), note how a key change from G to D is achieved (note key changes to the V chord is very common!). This uses the concept of pivot chords. When we play G which is the I chord in key of G we can consider it also to be the IV of D major. Then we play a D major (I of D major), Em (ii chord) then A (V). While the first 3 chords G, D and Em can be from the key of G, it is this ambiguity that allows us to change keys. The real surprise comes with the A major chord which should be Am in key of G (we raise the C to C#). We can see how the 8th measure on page 2 ends on D making the key of D fairly obvious.
We will use this knowledge in future posts and via my Baroque Improvisation Course.