Bach – Invention No. 1 in C Major, BWV 772 with Sheet Music
Upon listening to Bach’s Invention No. 1, many students often comment that it is “like a conversation”. Of course, this is true of many of Bach’s great contrapuntal works because that’s the nature of counterpoint: 2 or more melodies (also known as voices, parts or lines) of equal importance sounded together.
What’s the subject of the conversation? The subject is clearly this melody that takes up one whole bar plus a sixteenth note.
The subject and its motifs are guided by an underlying harmonic progression. Overall, the structure of the piece is in three parts:
- Section A: in the key of C major: bars 1 to 6
- Section B: starts in G major and ends in A minor: bars 8 to 14
- Section C: brief visits to several related keys and a return to C major: bars 15 to 22.
Despite being just 22 bars long, we still get a great example of tonal music at work. Section A establishes the tonic. Section B moves away from the tonic and towards the dominant. Section C begins in the relative minor of the original key, and then goes through some other related keys briefly before returning to the tonic.
The key scheme is deceptively simple going through a number of closely related keys:
C major -> G major -> D minor -> A minor -> D minor -> C major -> F major – C major
Most importantly, observe how the motifs themselves always begin on a weak part of the bar. Because of this they overlap and connect over the bar lines (or over the strong beats) and this continually drives the music forward.
When a cadence is due at the end of a phrase, Bach changes the rhythm slightly so that the music conforms to the pulse. At these cadence points, the motifs are abandoned for a very short while and what we get instead are melodies and rhythms that begin and end on the beat.
Motifs, rhythm and harmony all work together at the same time to hold the whole structure together. This is why the piece is admired so much by composers – it’s a mini masterpiece and a gem of musical architecture.