Analysis of the Allemande from Lute Suite 1, BWV 996 by J.S. Bach was most rewarding. Here is another piece I have played for generations without ever considering it's complexities. For a little eighteen measure piece it's loaded with them. My source for this analysis was the Neue Bach-Ausgabe with minor alterations to make it playable on guitar. If you are interested I have the entire suite available in a performance edition on my Buy page. Here is the breakdown:
We have the typical binary dance form in which two distinct parts are apparent with authentic cadences and repeats.
Part 1 MM. 1-8
We begin in E minor and as is typical but maybe not quite as common, we end in the dominant key of B minor. Generally the move is to the relative major key. Bach does move into G major in the middle of this first section (mm. 3-5) before setting up the main cadence in B minor in bars 6-8. Notice the use of the Picardy third in measure eight.
Part 2 MM. 9-18
This B major triad (V) begins section two and does resolve to tonic (E minor) as would be expected, but in retrospect (working backwards from the cadence in measure thirteen) I am going out on a limb and claiming we will hear this as the V/ii in D major as the analysis shows. There is no doubt we have a move into D major in measures nine through eleven before returning to B minor at the cadence in measure thirteen. There is an interesting twist here in measure thirteen. We expect a B minor triad but as we move through the measure we actually get a B major triad which functions as the dominant of the following E major triad. The tonal center though is still B minor, not B major. My idea was to make it as simple as possible and show the key centers as B minor along with its relative major key of D major in measures nine through thirteen. We get the return to E minor in the second half of measure thirteen but not before touching on its relative major key of G major by way of the classic descending fifth progression in measures thirteen through fifteen, mirroring what he does in measures nine through eleven.
The final cadential ii-V-I again ends with the E major triad (Picardy third) as in the end of part one.
My reduction staff shows what I believe to be the contrapuntal simplification of the piece using mainly a three-part reduction along with my reasoning for what I believe are the harmonic implications. I think it works well if you play through the piece as written and then try the reduction. Let me know what you think.
1) Notice the use of the F# minor (ii) chord in measures two and sixteen. We all know the ii chord in minor keys is usually a diminished triad but in this case we can see that because of the use of the melodic minor scale (raised sixth and seventh degrees ascending) in the inner voice, the ii chord is now a minor triad. There is an interesting chromatic use in measure sixteen where the sixth degree is first natural (C) and then raised (C#).
2) The chromatic bass line in measure five making use of a secondary leading-tone triad that resolves deceptively before bringing us back to the home key of E minor with its leading-tone triad.
3) The scales used at the final cadences in measures eight and eighteen. In measure eight he ascends a B major scale but then on the way down lowers the sixth degree. It is as if Bach is reminding us that we are indeed in E minor and not E major. He does a similar thing in measure eighteen where he raises the third degree G to G-sharp (Picardy third) but leaves the sixth and seventh degrees (C and D) natural. Again reminding us that the key is E minor and not E major.
Even with this little piece the genius of Bach is apparent and confirms my belief that we were indeed visited by ancient astronauts and Bach was a direct descendant.