Form in Art Music
All of the archetypal forms (strophic, binary, ternary, rondo, and theme and variations) play a role in art music. Johannes Brahms's Lullaby (Wiegenlied) is an example of strophic form. Johann Sebastian Bach's Suites for Solo Cello consist primarily of binary form dances. Minuets from the Classical period (which appear often in composite forms like symphonies and string quartets) are ternary. Ritornello form, the Baroque version of rondo form, was used in the fast movements of concertos by Antonio Vivaldi and others. Theme and variations form can be seen in Wolfgang Amadeus Mozart's Variations on Ah, vous dirai-je, maman (better known to us as "Twinkle, Twinkle, Little Star") and the second movement of Joseph Haydn's "Emperor" String Quartet.
Art music forms are also sometimes based on themes - a motives, phrases, or melodies that will be repeated, transformed, and varied over the course of the piece. Fugues and the sonata form are based on themes in this way.
Fugue
J.S. Bach is the composer most famous for writing fugues, and his instrument of choice was the organ. Bach often paired his organ fugues with introductions called 'toccatas' or 'preludes' that are through-composed and seem to imitate improvisations. These free introductions contrast with the fugues themselves, which contain complex and highly-ordered imitative counterpoint (polyphony).
Each fugue begins with an exposition, which consists of several successive statements of the subject (S), or primary contrapuntal theme. After the exposition, statements of the subject alternate with free sections called episodes (E). Below is a video of Bach's "Little" Organ Fugue in G minor (BWV 578) and a chart showing the form of the piece. See if you can follow along with the high and low statements of the subject.
| Exposition | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| S | E | E | E | E | S | E | ||||||||
| S | S | |||||||||||||
| S | S | |||||||||||||
| S | S | S | ||||||||||||
Bach, "Little" Fugue in G Minor BWV 578
Sonata Form
Before discussing sonata form, it should be noted that sonata form is not the same thing as a sonata. A sonata is a particular genre (a solo piece often written for piano and originally intended for amateurs), whereas sonata form is a form that can be used in a variety of genres. Sometimes the term 'sonata-allegro form' is used to help make that distinction clear, but 'sonata form' is the preferred term.
Sonata form is a sophisticated form that plays a significant role in art music. Classical composers such as Mozart and Haydn were among the first to develop and use sonata form, and it quickly became the standard first-movement form for all composite forms (such as symphonies, concertos, and string quartets).
Sonata form is comprised of three major sections, where the third is a rough repetition or variation of the first. Sonata form gives these sections specific names: exposition (same term used for the beginning of a fugue), development, and recapitulation. Although this structure seems very similar to ternary form, when it comes to the harmonic structure of the piece, sonata form is really in two sections: the first part where I moves to V, and the second part where V moves back to I. This leads us to associate sonata form more closely with binary form than ternary form.
| Exposition | Development | Recapitulation | |||||||
| First Theme | Transition (bridge) | Second Theme | Closing Theme | First Theme | Transition (bridge) | Second Theme | Closing Theme | ||
| I → V | V → I | ||||||||
Although they are not included in the chart above, it is also quite common for pieces in sonata form to include both an introduction prior to the exposition, and a coda after the recapitulation.
Exposition
The exposition introduces the main themes. The melodies that comprise these themes are designed to be memorable so that audiences will recognize them when they return in the recapitulation. Within the exposition (and recapitulation) are transitional sub-sections that are designed to move the music forward into the next section. Transitions are full of melodic and harmonic movement designed to build energy and momentum.
Development
The middle section, the development, plays with the themes introduced in the exposition and allows them to take the harmony to new and unexpected places. The style of the development section is agitated and unstable harmonically. Developments often include contrapuntal material as well.
Recapitualtion
The recapitulation is not a literal repeat of the exposition, but it brings back the original themes in their original order. These restatements may be varied, but the recognizable themes nonetheless give listeners material that is more stable and familiar than that of the development. It is in the recapitulation that we begin to shift towards the ultimate resolution and conclusion of the piece. The actual conclusion of a piece in sonata form is usually accomplished by a coda inserted after the recapitulation.