As the subtitle ‘In Praise of Johann Christoph Bach of Ohrdruf’ indicates, this piece was written to be dedicated to his elder brother Johann Christoph, who educated him in place of their deceased father. It can be seen as a lengthy fugue, but new counter-subjects and episodes constantly appear within it, and during this time, it modulates rapidly through various keys, resulting in highly varied content. It is a fine work that expresses joy towards his brother in a bright and lighthearted manner.