Bach composed Two Part Inventions in K then (before 1723) for teaching purposes, particularly his eldest son Wilhelm Friedemann.
In Bach\'s copy of 1723 he prefaced the collection of Inventions and Sinfonias with these words: "Honest method.
The Notebook contained two-Part pieces, Preambulum, which were later named as Inventions.
The earliest copy of this work, supposedly written by Bach\'s own hand, is found in the Wilhelm Friedemann Clavierb chlein (Piano Notebook), started on January 22 1720.
Bach composed Two Part Inventions in K then (before 1723) for teaching purposes, particularly his eldest son Wilhelm Friedemann