F minor, 3/4 time.

While the themes of each piece in the Inventions are generally concise, the theme of this piece is comparatively long, spanning four measures. The expressive melody in F minor is particularly suitable for learning the 'cantabile manner' that Bach noted in his preface.

The piece can be divided into exactly two sections. In the first section, the upper voice first presents the theme, while the lower voice plays the counter-subject as if accompanying it. Then, from measure 5, both voices invert, and from measure 9, the music modulates using the theme and counter-subject. In the second section (from measure 17), contrary to the beginning, the lower voice presents the theme in the dominant key.