Early history
With the larger forms of instrumental music there are extended musical pieces, usually called movements, which in their succession and totality make up a larger whole. An important unifying factor is key: a single key often dominates the work, others being used for contrast. This idea goes back at least to the Baroque, when two formal types were established: the first is the sonata da camera, or chamber sonata, consisting of a series of dances in the same key (also known as partita and, later, suite). By J.S. Bach’s time (1685–1750) a set arrangement of dances was common: allemande (moderate duple time), courante or corrente (fast triple time), saraband (slow triple time), and gigue (fast duple or quadruple time), usually with some other dance inserted between the saraband and the gigue. The other type is the sonata da chiesa, or church sonata, which consists of four movements, again all in the same key, in a slow–fast–slow–fast succession. The distinction between the two types is explicit in Bach’s sonatas and partitas for unaccompanied violin: the sonatas are in the “church” form, whereas the partitas are suites. Other large forms of Baroque music are the two types of overture: the French, in two parts, the first slow and stately, the second fast and fugal; and the Italian, in three movements in the succession fast–slow–fast, the middle movement usually in a different key. The instrumental concerto after 1700 usually employed the same scheme as the Italian overture.
The sonata
Around 1750 a combination of these types produced the forms most common in the standard repertory of concert music. The sonata became a piece for either a keyboard instrument or a solo instrument accompanied by keyboard. It ordinarily consisted either of three movements in the arrangement fast–slow–fast or of four, with a minuet inserted between the slow movement and the finale; but there are examples of two-movement sonatas, notably by Beethoven, and even of one-movement sonatas (e.g., by Domenico Scarlatti, the Italian-born composer to the Spanish court). Usually all movements except the slow one (and sometimes the trio, as well) are in the same key. The first movement typically is cast in the sonata form, the slow movement in one of the reverting schemes (often ternary), and the finale either in sonata or rondo form; but variation form may appear in any of these movements.
This large form is also used in chamber music, particularly the string quartet, and in the large form of orchestral music, the symphony, both of which ordinarily have four movements. Notable exceptions to this are the late quartets of Beethoven as well as those of the 20th-century composer Béla Bartók, the latter in two instances using what is called the “arch form,” a large reverting arrangement, A B C B A, each element being a separate movement; there are innumerable other exceptions. The concerto, on the other hand, adheres more to the older three-movement form. The various kinds of late 18th-century entertainment music (cassation, divertimento, nocturne, serenade, and the like) may employ any of a number of arrangements, ranging from three movements all the way to six or more.
Cyclic form
Some authorities believe that since the 18th century such sonata-form compositions have been organized by the use of a few musical thematic motives, often submitted to considerable variation throughout. Compositions organized in such a way are said to be in cyclic form. While this becomes important in the 19th century, the extent to which it characterizes the Classical period is a matter of some controversy at present.
Fantasias and program music
Simultaneously a much freer form was cultivated, beginning in the late 18th century, the fantasia, primarily for keyboard, notably in the hands of Carl Philipp Emanuel Bach. Consisting of an indefinite number of highly contrasting sections, surprise and expression were of prime significance.
The fantasia, along with the overture to a play or opera, was the precursor of the large forms of orchestral program music of the 19th century, in which an extramusical content (usually a narrative of some kind), called the program, is expressed in the composition. There are two main types: the program symphony, associated with Hector Berlioz, in which the norms of symphonic form are for the most part preserved, and the symphonic poem, associated with Franz Liszt and Richard Strauss, in which the composer allows the extramusical subject matter to determine the structure of the composition. Some 19th-century concert overtures by German composers such as Felix Mendelssohn and Robert Schumann belong to this type of composition. Important here is the association of musical themes with aspects of the program, the themes being used throughout the work, often in varied forms.
Another arrangement is called the suite, which no longer consists exclusively of dances but also of instrumental pieces of all kinds. Usually some common element runs throughout: a cyclic theme may be used, as in Schumann’s Carnaval or the Russian composer Modest Mussorgsky’s Pictures from an Exhibition, or the music may originally have been intended for use with a play (Mendelssohn’s music to A Midsummer Night’s Dream or the Norwegian Edvard Grieg’s for Henrik Ibsen’s Peer Gynt).
Opera and oratorio
Among the large forms of vocal music, opera and oratorio are the most significant. Both are extended works in which a narrative is set to music. While an opera is performed in a theatre, an oratorio is a concert piece. Both may be either sacred or secular. A special type of oratorio is the Passion, the setting of New Testament accounts of Christ’s crucifixion. The cantata may be regarded as a smaller form of oratorio.
Operas and oratorios ordinarily consist of several musical genres: recitative (imitating the manner of speech), aria, ensemble and choral pieces, often with instrumental interludes and an overture (most overtures of the late 18th and 19th centuries being cast in sonata form). Opera often includes ballets and large sectional finales at the ends of acts. With respect to the oratorio, Handel greatly increased the role of the chorus in his work with this genre (especially Israel in Egypt), an example seized upon by his successors. Oratorios also differ from operas in that they frequently make use of a testo (narrator), who relates the events of the action, usually set in recitative style. Stravinsky’s Oedipus Rex (1927) combines the two traditions.
Whereas operas are usually composed as a series of enclosed musical forms, the German composer Richard Wagner devised a special kind, known as music drama, in which the music is continuous and in which the distinction between recitative, aria, and ensemble is largely eliminated. Instead, Wagner used a flexible melodic line which he referred to as “tone speech.” Wagner also greatly increased the role of the orchestra, stressing the technique of thematic development and transformation borrowed from instrumental music and further associating each theme with an aspect of the operatic plot, such themes being known as leitmotivs (“leading motifs”).
The mass
Another large vocal form is the mass, the earliest polyphonic settings of which date from the 14th century. At first the mass was set in cantus firmus style, each movement built on the appropriate Gregorian chant melody, as in the mass of the French composer Guillaume de Machaut. In the 15th century a Burgundian composer, Guillaume Dufay, and his contemporaries developed the cyclic mass, in which a single cantus firmus was employed throughout. This idea was extended in the parody mass, built by elaborating thematic material taken from an existing polyphonic work, usually a motet or chanson; most 16th-century masses are of this kind. In the Baroque mass, each segment of the text is treated as an independent composition (aria, duet, chorus), similar to the procedure in a cantata or oratorio, except that no recitatives are used. J.S. Bach’s Mass in B Minor is of this type.
In the 16th and 17th centuries, Monteverdi and others grouped madrigals into a kind of cycle around a particular subject; should a dramatic text be involved, the form is known as a madrigal comedy. In the 19th century and after, similarly grouped songs with piano accompaniment are known as a song cycle (e.g., those by Beethoven, Schubert, and Schumann).
20th-century modifications
In the 20th century many composers have continued to use the traditional forms, although in other respects their work makes significant departures from what had been established. Others have virtually discarded them. Radically new elements have been introduced to serve as structural units: instead of the traditional phrases and motives, composers have come to employ what they call “sound events,” combinations of textures, types of timbre, aggregates of different simultaneously sounding pittches, and the like. An early example is afforded by the notion of the melody of timbres—the Klangfarbenmelodie of Arnold Schoenberg and Anton von Webern. The broadest possible range is included in the conception of a sound event: not merely tones but also noises; in fact, sounds of all kinds. These sound events have been arranged in a complex manner. An important principle of organization has been serialism, originally applied only to pitch, so that the pitch content of the work is decided by reiterations of a series (set or row) of pitches that has been determined in advance (e.g., in the 12-tone compositions of Schoenberg and Webern). Since 1945 the serial principle has been extended to other aspects of music as well: durations, dynamics, and types of attack and tempi, as in the music of the French composer Olivier Messiaen and the German Karlheinz Stockhausen. Other composers, including Stockhausen and the Greek Yannis Xenakis, have used numerical relationships to determine the structure of compositions mathematically. Still others have conceived of form as a dynamic interaction between contrasting and continually evolving sound events—the French composer Edgard Varèse and the American Elliott Carter. Simultaneously, there are works, such as those of the American John Cage, in which the form is not predetermined by the composer but left to chance, such pieces being called indeterminate or aleatory. These statements apply particularly to electronic music.