The ternary principle was initially defined as one of
statement, contrast, and restatement. The rondo principle may be
viewed as an expansion of the ternary principle insofar as it involves
statement followed by alternating contrasts and restatements.
Rondo movements, therefore, tend to be perceived in five, seven, or
nine (or more) main parts, and are labeled A-B-A-B-A, A-B-A-C-A-B-A,
A-B-A-C-A-D-A, etc., depending upon whether the melodic/thematic
material in the contrasting sections is interrelated or not.
Part A is commonly called the refrain or ritornello.
Part B is variously designated: couplet, digression, episode
or intermezzo, depending to some extent on the period under
investigation.
The more contemporary designations (which we will use) are:
- Part A--primary section
- Part B--alternating section.
The rondo principle, although exploited extensively in earlier
vocal music, was not systematically applied to instrumental music
until the middle of the 17th century. It may be found on a
relatively large scale in the ritornello movements of the
Baroque concerti grosso.
In the rondeau, an instrumental dance, the rondo principle
may be easily perceived, as it is in the classical rondo that
followed it.
As has been discussed earlier, composite forms are those in which
any part of a large structure may be clearly identified as
representing a separate, complete expression of a structural
principle. Composite ternary structures are examples of such
forms. So are rondos that contain binary structures as parts
of their design.
Sonata-rondo, a common rondo type of the 18th and 19th
centuries, may be considered a hybrid form, in which tonal, motivic,
or functional principles characteristic of sonata-allegro structures
are integrated into a basic rondo design.
The following diagram compares the elements of typical
sonata-allegro and sonata-rondo forms, and illustrates the way in
which the elements of the principles are combined:
| Sonata-Allegro (Binary) |
| Part A |
|
Part B |
|
|
| Exposition |
|
Development |
Recapitulation |
| I --- ... |
V - - - - - -
- V |
- - - - - - - - - V |
I - - - ... |
I - - - - - - - - - I |
| I --- ... |
III - - - - - - - III |
- - - - - - - - -
V |
I - - - ... |
i - - - - - - - - - i |
| Group 1 |
Group 2 |
Motivic Manipulation |
Group 1 |
Group 2 |
| Sonata-Rondo
(Sectional) |
| A |
B |
A* |
C |
A |
B |
A |
| I - - - - - I |
V - - - ... |
I - - - - - I |
- - - - - - V |
I - - - - - I |
I - - - ... |
I - - - - - - I |
| i - - - - - - i |
III - - - ... |
i - - - - - - i |
- - -
- - - V |
i - - - - - - i |
i - - - ... |
i - - - - - - i |
| Primary Section |
Alternating Section |
Primary Section |
Motivic Manipulation |
Primary Section |
Alternating Section |
Primary Section |
To summarize: In the sonata-rondo, after the first return
of the primary section, the remaining sections follow the tonal and
functional relationships as the tonal and motivic result of
the opening sections.
*Were it not for the first restatement of Part A, the structure
would be perceived as being governed by the binary principle.
