“This piece is found in many copies from Bach’s day,” (Netherlands Bach Society). “Around 100 years after his death, it was published no fewer than four times in rapid succession. Bach’s pupil Johann Georg Schübler thought the theme was so successful that he made a fugue out of it himself. So it was an immensely popular piece … when organists refer to this piece as the ‘Little’, it is not meant to be denigrating, but is purely to avoid confusion with Bach’s other, longer fugue in G minor, BWV 542, the ‘Great’.”
In the “Little” Fugue (1709), “Bach was able to take the earlier vocal polyphony of the renaissance period and apply it to the organ fugue,” (Understanding Music). “This is regarded as one of Bach’s great achievements.” The piece begins in G minor, shifts to the closely related key of D minor as the second voice enters with the theme (0:20), and continues to unfold from there.
modulationoftheday.home.blog 