Analysis of Bach's Two-Part Invention No.1

A little earlier in the course I researched Bach's Fugue No.16 in G minor, but that research focused more on the relationship between the subject, answer, countersubject etc than contrapuntal devices such as inversion, augmentation etc. With that in mind, I decided to research Bach's Two-Part Invention No.1, partly because it is a piece I already play on the piano, and partly because it is absolutely full of the type of compositional techniques I am trying to study. A single website gave very clear and succinct information on exactly what I needed to know, and that is where I found the following information. The link for that webpage can be found at the end of this blog entry.

Analysis

Bars 1-2 - The subject is stated in upper voice, then immediately imitated by lower voice and octave lower. The upper voice then repeats its material in the first bar, but played a fifth higher.

Bars 3-4 - The upper voice plays a sequence based on the first four notes of the subject, but which are transformed by inversion. The first four notes of the subject are also transformed by augmentation and used by the lower voice during the sequence.

Bars 5-6 - The lower voice presents the subject in its original form, after which the upper voice plays it in inversion. During this time the quavers in the lower voice are reminiscent of the augmentation treatment in the previous bars.

Bars 7-8 - A repeat of bars 1 + 2, but with 'inverted counterpoint' - the upper and lower voices have swapped material.

Bars 9-10 - The subject appears in both voices transformed by inversion while undertaking an ascending sequence.

Bars 11-12 - The sequence in bars 3-4 is now repeated, but in inverted counterpoint.

Bars 13-14 - The subject is presented in its original form in the upper voice, and in inversion in the lower voice.

Bars 15-18 - A series of imitations presents the subject transformed by inversion (15+17), and in its original form (16+18).

Bars 19-20 - A sequence similar to that found in bars 3-4 and 11-12, however the subject featured in the upper voice is in its original form rather than inverted, and the four note augmentation in the lower voice is also inverted.

This analysis was not my own work, I simply studied the information and presented it in (mostly) my own words. The excellent article that I studied can be found at:

http://www.teoria.com/articulos/analysis/BWV772/index.htm