Binary and ternary forms, minuet and trio
Music theory · Musical form · Level 3 · 14 min
At the scale of a whole piece, we label the large sections with letters: A, B, C… The same letter means the same material; a primed letter (A') means a variant.
Binary form: ||: A :||: B :||
Two sections, each repeated. Typical of Baroque dances (minuets, gavottes, sarabandes, gigues in Bach's suites) and of Scarlatti's sonatas. The key plan is essential:
- A starts in the tonic and modulates to the dominant (or the relative major in a minor key);
- B starts in that new key and returns to the tonic.
M:3/4 L:1/4 K:G |: "G"G A B | "D"A2 D | "G"B c d | "D"A3 :| |: "D"d c B | "G"B A G | "D"A F D | "G"G3 :|
When the end of B brings back the opening of A (in the home key), it's called rounded binary (A ||: B A' :||): the ancestor of sonata form.
Ternary form: A B A
A first section that is complete and closed (it ends in the home key), a contrasting section (another key, another character), then the return of A, often varied or ornamented. It's the form of many Chopin nocturnes, of the “Raindrop” Prelude (Op. 28 No. 15: D♭ major – C♯ minor – D♭ major) and of many Romantic character pieces.
Minuet and trio: a ternary made of binaries
In Classical sonatas, quartets and symphonies, the third movement is often a minuet (later a faster scherzo). Its form:
| Minuet | Trio | Minuet da capo |
|---|---|---|
| binary (||: a :||: b a' :||) | binary, contrasting, lighter | played again without repeats |
The trio owes its name to the Baroque era, when this middle section was played by only three instruments. At the end of the trio, the marking Menuetto da capo sends you back to the beginning.