For those not so familiar with Bach,
He was first and foremost a virtuoso keyboard player. Secondly he was a music teacher. All his written keyboard music is really there to teach you how to write music and how to play.
His goal was, in a way, to teach.
The well tempered Clavier books, start of easy, and gets harder and harder, with new techniques.
It was also to show how important the new tempering of the tuning on keyboard was, but that is another story.
Thirdly, and in a sad way. He was not recognized in his day for his writhing of music.
There was really just 2 pieces he was “famous” for.
That was
“Toccata and Fugue in d minor, BWV 565” and
“Chromatic Fantasia and Fugue in d minor, BWV 903”.
First of the who has a “Toccata” in the beginning.
Toccata is a improvisation where you use timing in your improvisation. In example. Plays one scale faster and faster, slow suddenly down tempo, and so on. All to express the melody’s. Fantasia is a way of improvisation. Less rules than anything.
Mark that both has Fugue parts.
And that is the technique Bach first and foremost are known for.
Fugue technique is a way of using a melody and making a musical peace out of it.
There is not much rules, only suggestions made by Bach’s music, but the rules must be, that the melody is used again and again and in new ways all the time.
And Fugues does not need more than one voiced instruments to work.
Here is Bach "Sonata No. 1 in G Minor, BWV 1001: II. Fuga: Allegro"
Øyvind Skald,
the not so famous skald