The counterpoint appearing in the left hand from the third beat of measure 13, extending to the second beat of measure 14, forms a rhythmic motif common to motives a and b. In measure 19, theme c appears in its complete form in the right hand, while the left hand repeats the motive of the preceding two beats twice. The left hand in measures 20 and 21 presents an augmented form of the motive, and the first two beats of the right hand in measure 22, though not strictly motive a, are an augmentation of a part of the inversion of motive a' (a variant of a) appearing in the left hand in the same measure.

Score example provided by Bärenreiter Verlag

No. 13 in A minor

Among the 15 Inventions, this is considered technically the most difficult. Learners will require meticulous practice, and performers and teachers may find this Invention serves as an excellent etude. Fingering might be crucial for this Invention, as it could influence the difficulty. The piece is strong, fast, and intense. Eighth notes should be staccato and played at a reasonably fast tempo.

Sequences follow one after another, almost to the extent that it's no exaggeration to say the piece is built almost entirely on sequences, like a storm of sequences. Learners should first undertake a meticulous analysis. From there, let's examine the piece. (Note) The following analysis and performance suggestions are merely one example.

• Measures 1-2: The subject appears in the right hand.
• Measures 3-4: A one-measure sequence. The volume in m. 4 should be slightly reduced compared to m. 3.
• Measures 5-6: A two-beat sequence. As it descends, a diminuendo should be applied. It then modulates to C major. Assuming C major is a softer key compared to A minor, the volume should be restrained.
• Measures 7-8: Similar to mm. 1-2, the subject appears in the right hand, but in C major.
• Measures 9-10: A one-measure sequence. The volume in m. 10 should be reduced compared to m. 9.
• Measures 11-13: A two-beat sequence. Although it descends, it leads to E minor, and m. 14 features a diminished seventh chord; therefore, a crescendo should be applied to reach m. 14.
• Measures 14-17: A one-measure sequence. Since the original key awaits in m. 18, if m. 14 is played fortissimo, the volume should gradually decrease to reach m. 18.
• Measure 18: For one measure, the subject appears in a varied form.
• Measures 19-21: A one-measure sequence. Although it descends, whether to apply a crescendo or diminuendo here is a matter of differing opinions. The author would apply a crescendo.
• Measures 22-25: The subject is varied and concludes with only sixteenth notes.

For your reference.