Bach BWV1019

[Tetrachord]

Can anyone tell me why this solo keyboard movement is in Bach's Sonata BWV1019, which is a work for Harpsichord and Violin?

It starts here at 5'23" (This piano version was the only decent U-Tube link I could find):

https://www.youtube.com/watch?v=pfdkdox5sTo

[Richard Barrett]

Can anyone tell me why this solo keyboard movement is in Bach's Sonata BWV1019, which is a work for Harpsichord and Violin?

The obvious answer is: why not? (BWV1019 exists in three different versions, only two of which contain this movement.)