Musical Forms

A composer setting out to write a piece has a basic form in mind, much as a chef builds upon a basic recipe in creating a fine dish. Both composer and chef begin with good ingredients. They use a basic form or recipe to put their materials into good order and effective combinations. Finally, they add the personal touch that makes their creations works of art. Each of the forms to be described in this article has served as a guideline to composition and to perceptive listening.

Each form makes sense. Each provides a recipe that has been available to masters and to beginning composers alike. In the hands of an imaginative composer each form invites variant layouts, so that each composition may have its own turns of phrase, its own subtlety, its own wit. You can best appreciate a composer’s felicity of invention and expression by becoming familiar with the prototypes: two-reprise form, three-part forms, rondo forms, variation, sonata form, concerto forms, fugue, and free forms.

Two-Reprise Form

In its simplest version, this form consists of two periods, each eight measures in length. These periods were called reprises in seventeenth- and eighteenth-century music, since each period was generally repeated or reprised in a thirty-two measure A A B B sequence. Many traditional songs are laid out according to the two-reprise plan (although they do not repeat each period), among them “Drink to Me Only With Thine Eyes,” “Jingle Bells,” and “Yankee Doodle.” Popular and court dances from the medieval period to the nineteenth century were performed to music written in two-reprise form.

The beauty of this form is its clarity, balance, and economy. Being short — and usually featuring a fetching tune — it is clear. Its balance lies in the elegant statement-response relationship of its two periods. The first period ends with the impression that the music will probably continue, creating an open-ended effect. The second period ends with a final arrival, creating a solid effect of closure. The economy of the two-reprise form arises from the fact that when each short period is repeated the composer and listener get double the mileage — you hear each twice while sensing the balance that repetition promotes.

Ex. 1

First reprise of a two-reprise form. Mozart: Sonata in A Major, first movement.

Example 1 from Mozart’s Sonata in A Major is the first reprise of a short two-reprise form. This example ends in the home key; Mozart adds another period just to balance the form. Example 2, from the first movement of Mozart’s Sonata in D Major, gives both reprises. Here, the first reprise modulates to the dominant key, A major. It embodies the I-V phase of the I-V; “x”-I plan.

Ex. 2

Two-reprise form, modulating to dominant key. Mozart: Sonata in D Major, third movement.

The shift of key in Example 2 raises a harmonic question: “What about getting back to the home key?” This is the task of the second reprise. After a bit of harmonic probing — “x” — a momentary pause ushers in the final bit of music that settles itself neatly in the home key, I.

If you count the measures in Example 2 you will find that the second reprise has an extra measure (9). Mozart has done a bit of subtle juggling, stretching out the beginning of the second reprise to build an effect of suspense that makes the return of his tune especially gratifying.

Nonmodulating two-reprise forms tend to be short; their stay-at-home harmony reinforces their neat little symmetries. On the other hand, if the composer decides to shift to another key — I-V — at the end of the first reprise, he opens the door to considerable room for expansion. Example 3, from Bach’s Suite in E Major, illustrates such expansion. At measure 7, he reaches the dominant with a light cadence. To nail down the effect of the dominant, however, he must continue for five more measures before reaching a powerful cadence in measure 12. Now the way back to the home key, “x”, has to overcome the persuasiveness of this modulation in order to make the final return home, I, convincing. This will take some thirty measures, of which Bach devotes the last seventeen to securing the final close in the home key.

Ex. 3

Extended two-reprise form. Bach: Suite in E Major, bourrée.

To get some idea how Bach expanded the two-reprise form, compare the actual piece (Example 3) with its reduction to the minimal sixteen-measure form (Example 4). In the reduction, notice that measure 4 links perfectly to measure 9, so that measures 5-8 act as a parenthesis; also, measure 16 links just as smoothly to measure 39, so measures 17-38 amount to a substantial excursion and return. Despite the length of the two-reprise form in this piece. Bach obviously had the short model clearly in view at all times, since it represents the boundaries of the form. (The piece itself is based on a dance, the bourrée. This bourrée, however, is not danced; it simply reminds the hearer of the actual dance music from which it sprung.)

Ex. 4

Reduction of Ex. 3 to a 16-measure two-reprise form (with corresponding measure numbers).

What happens to the melody in a two-reprise form? Well, here the composer has some additional options. He can bring back his original tune to close the form, as Mozart did in Example 2, or he can match endings, as Bach did in Example 3. Or, as in “Jingle Bells,” the music can go on to something new in the second reprise. The intriguing interplay between a firm yet flexible framework and a wide range of options has made the two-reprise form a favorite for composers since the seventeenth century. Lully, Rameau, Bach, Handel, Haydn, Mozart, Beethoven, Schubert, Chopin, Mendelssohn, Schumann, and Brahms have laid out many of their short pieces and songs in two-reprise form. The form also shapes minuets, marches, waltzes, polkas — most of the traditional popular music of the past two centuries.

The two-reprise form also has modular possibilities. Like modular furniture, individual pieces can be linked, coupled in various ways to build larger works. Hence the term couplet form, which designates a piece made up of a series of these short forms.

Three-Part Form

This is the simplest coupling, an A B A arrangement, in which each letter represents a complete two-reprise form. The B section of a three-part form is designated as a trio. This term comes from the tradition of the seventeenth and eighteenth centuries to have this middle section played by a small ensemble of solo instruments, generally a trio. Beethoven’s familiar Minuet in G is a model for three-part form. Each of its four periods is a trim eight measures in length, neatly segmented every two measures. Its melodies are elegant and graceful, set off against each other in gentle contrast.

In concert music you will hear three-part forms in the minuets and scherzos (this term means “joke”) of symphonies and chamber music. By Beethoven’s time the eighteenth-century minuet was often speeded up to become a scherzo. This second-generation minuet took on an exuberant, sometimes violent manner, with touches of humor ranging from subtle wit to pie-in-the-face slapstick, as in the scherzo of Beethoven’s Symphony no. 2. For the listener, the three-part form as presented in minuet or scherzo style is the most easily grasped of all forms. In keeping with this accessibility, the music itself is usually pleasant and open, touching upon a variety of moods. For example, Mozart gave the minuet in his Symphony no. 39 in Eb Major a stately manner. In contrast, the trio is a bucolic Ländler, a country waltz such as might be played at a peasant festival.

Because of their brevity and their neatly laid out periods, these three-part forms can etch little vignettes — scenes that appeal immediately to listeners. We hear hunting calls, pastoral tunes, courtly attitudes, bold military gestures, even effects drawn from the contrapuntal intricacies of the learned style or the supernatural shadows of the Ombra.

The three-part form maintained its presence in the nineteenth and twentieth centuries. Johann Strauss often calls for the A B A relationship of the various reprises of his waltzes. Bela Bartok no doubt had a retrospective intention when he set the second movement of his Concerto for Orchestra, “II Giocco delle Copie” (“The Play of Pairs”) in an A B A form.

Rondo Forms

Rondo means “round” in Italian. In music it refers to a form in which a principal theme comes around again after intervening material. The principal theme is called a refrain; intervening material is designated by the term episode. In the earlier eighteenth century, rondos and their French counterparts, rondeaux, consisted of a chain of two-reprise forms typically coupled in this order: A B A C A D A. No specific number of alternations was prescribed, but three refrains were the general minimum for a rondo form. Some familiar pieces and their rondo layouts are:

Of these three examples only the Haydn finale represents the older type of rondo, with coupled two-reprise forms. The Beethoven and the Mozart finales spin out their material at length. They retain the rondo effect by a solid return to the refrain after the first episode. As you may gather, rondos, with their fetching tunes often recalled, are apt forms for finales. A rondo makes a nice dessert to top off the substantial repast of a symphony or concerto.

Variation Form

Variation has two meanings in music. Every musical passage is a variation of something already at hand to which the composer aims to give fresh value. But variation is also a form, in which the composer writes a set of short pieces based upon a preexisting theme. Like the three-part form and the rondo, these pieces are coupled, forming a set of variations. In its most familiar and attractive role, the variation form is a musical showcase, a fashion show in which the model (i.e., the theme) is the same, while the dress differs for each variation. Mozart, in the opening movement of his Sonata in A Major, gives a simple pastoral theme, then dresses up the theme with piquant embellishments (Example). He continues the variation process with other arrangements of rapid notes, several times assigning them to the accompaniment until the piece climaxes with a broadly scaled slow movement modeled after the aria (an operatic solo). Mozart’s aria-like piece, like all the variations, is shaped exactly to the two-reprise layout of the theme. A quick variation in the style of a contredanse (a popular eighteenth-century dance in duple time) winds up the piece, adding a few measures for an emphatic arrival.

Variation can take on a serious note and achieve great scope. The “Crucifixus” from Bach’s Mass in B Minor proceeds as a freely composed piece over a four-measure bass theme. Bach expresses the tragic mood with rich and complex contrapuntal textures and unstable harmonies. Beethoven sets the finale of his Eroica Symphony in variation form. He adapts the form to his own individuality in the middle of the movement, though, by breaking the two-reprise mold of the theme in favor of several extended, discursive variations in the learned manner.

Sonata Form

Sonata form is something of a wonder. It rose quickly to prominence around 1760-70. From that time until the early twentieth century composers cast the first movement of almost every sonata, concerto, symphony, or quartet — as well as many slow movements and finales — in sonata form. No other form has ever appeared so rapidly on the musical scene or caught on with composers of all nations so completely as did sonata form.

The term sonata means “sounded” in Italian — as distinguished from cantata, which means “sung.” In the seventeenth and eighteenth centuries these terms were applied to instrumental and vocal pieces intended for home, court, or church use. In the nineteenth century, music theorists began to apply the term sonata form to the form often used in first movements of instrumental works. Nowadays, it is commonly understood to signify the form described here.

Harmonically, sonata form has the same overall shape as the two-reprise form: I-V; “x”-I. Suppose we visualize this harmonic structure as a bridge. Terra firma is represented at the beginning and the end by a solid sense of the home key. In the two-reprise form there are two spans to this bridge, anchored in the middle by a strong cadence in V, the dominant key. This is exactly how Mozart laid out the portion of his Sonata in D Major that is shown in Example 2. Example 5 shows this scheme graphically.

Ex. 5

Graphic representation of small two-reprise form.

This is a small structure, taking less than a minute to traverse its ground. Now, imagine the same structural plan expanded to cover a much larger area — say, twelve minutes of music. The pillars would have to be anchored much more strongly and the spans would have to be strengthened and supported by subsidiary pillars. Perhaps also the bridge itself would have to be reached and left by approaches, as illustrated in Example 6.

Ex. 6

Graphic representation of sonata form.

This is the game plan of sonata form, a plan composers have followed consistently, no matter what paths they may take between pillars. The brackets, marked “Key Area 1” and “Key Area 2,” indicate the tonic and the dominant, which respectively comprise the harmonic sections of the first part. The main and subsidiary pillars, along with the section marked “x”, represent important stations in the form. The sections they enclose have been given names which, because of the consistency with which composers shape the general outlines of their sonata forms, fit quite well:

Composers imbed one or more salient themes in a sonata form. These serve as landmarks to help us get our bearings within the form. They act as areas of both arrival and departure. As we studied the small two-reprise form earlier in this chapter, we noticed how the theme, stated at the beginning of the piece in the home key, returned later to signal the reestablishment of the home key. Sonata form uses thematic material in the same way.

The I-V; “x”-I plan — both in its two-reprise and sonata-form versions — appealed to composers largely because of its sturdiness. Another advantage of the plan was its ability to embody harmonic contrast and reconciliation at long range within the sonata form. We can visualize sonata form as a debate or a test of authority. Imagine a confrontation between an emperor and a king. The emperor represents the home key (the tonic) with its own melodic material. The king represents the opposing key (the dominant) with its melodic material. The emperor states his initial premise, establishing the home key. The king challenges the emperor, introduces his key, and with considerable emphasis drives it home, thus achieving a temporary advantage. We have now reached the end of the second key area. The argument heats up in the development (the “x” section). The emperor’s key reasserts itself in the recapitulation and eventually absorbs the melodic material of the king’s key into his own realm, the tonic key, to show that it rightfully belongs at home. Mozart puts forth this harmonic-melodic action very elegantly in the first movement of Eine kleine Nachtmusik. Example 7 gives the melodic material for each key in the harmonic argument of this movement.

Ex. 7

Melodic material. Mozart: Eine kleine Nachtmusik, first movement.

Concerto Form

A concerto is a composition for one or more instrumental soloists and orchestra. In an orchestral performance it is the pièce de résistance, because it features a star performer. Two kinds of concertos are familiar to listeners — the Baroque concerto and the Classic-Romantic concerto. In the Baroque era the concerto was a vehicle for brilliant instrumental performance, in which a soloist would step out from the orchestra to do a solo turn, then step back to rejoin the ensemble. In the Baroque concerto we hear an interplay between a large group, called the tutti (“whole”) or ripieno (“full”), and one or more solo instruments, called the concertino. This interplay between orchestra and soloist promotes a vigorous, clean-cut style and features symmetrical arrangements of short, neatly turned figures, as in Example 8.

Ex. 8

Bach: Brandenburg Concerto no. 2 in F Major.

Handel: Concerto Grosso in D Major.

Handel: Concerto Grosso in F Major.

Bach: Violin Concerto in E Major.

The regular alternation of tutti and solo creates a form rather different from the two-reprise form. Instead of opposing two keys, the Baroque concerto circles around the home key — leaving it for a while, returning, leaving, returning, back and forth several times. Thus we hear both tutti and solo passages in various keys. This helps to maintain interest throughout the form. Example 9 gives the diagram of keys in the first movement of Bach’s Brandenburg Concerto no. 2 (see Example 8 above and this Example). (The heavy black lines represent areas of harmonic stability; the thin black line represents the home key as a level of reference throughout the movement. Areas where there is no heavy black line represent shifting, relatively unstable harmonic action.)

Ex. 9

Key scheme of Bach: Brandenburg Concerto no. 2, first movement.

The Classic-Romantic concerto, along with the symphony, represents the most impressive kind of instrumental music in the standard listening repertory. Many late eighteenth-century concertos maintained something of the tradition of the Baroque concerto, drawing the soloist out from the orchestra. Composers wrote concertos for clarinet, flute, oboe, bassoon, horn, trumpet, violoncello, viola, and harp. But the dramatic possibilities of the solo concerto in the late eighteenth century led composers to showcase the more brilliant and spectacular instruments, the violin and the piano, as soloists.

In his late piano concertos — those he wrote for himself to perform in Vienna — Mozart gives a panorama of concerto composition that has profoundly influenced concerto procedure for almost two hundred years. In these works we find both the lively give-and-take that characterizes the Baroque concerto and also the dramatic opposition of forces that distinguishes the Classic concerto. Further, in Mozart we meet the brilliant virtuoso soloist, the immediate predecessor of the Romantic hero-musician of the nineteenth century, as well as the ancestor of generations of composer-performers.

Structurally, concertos are laid out like other works of big scope. Generally there are three movements. The first is usually a quick piece in sonata form, modified to include an orchestral tutti in the tonic key at the opening, before the key area plan begins to unfold. This opening tutti is a theatrical strategy. It prepares the audience for the grand entrance of the soloist, much as a play or opera will frequently hold back the appearance of the main character until expectation is built up. Meanwhile, the orchestra does something very ingratiating: it presents the principal melodic material of the movement in the home key, like a preview of coming attractions. And concerto themes do tend to be attractive and somewhat more numerous than those in the usual symphonic sonata form, thereby giving the soloist opportunity to sparkle.

The middle movement of a concerto is slow and shows a close affinity with opera — specifically the aria — in the broadly singing style generally favored by most concerto composers. The finale picks up the pace again with fetching tunes laid out in rondo or variation form. One of the most delightful of Mozart’s concertos is his Piano Concerto in C Major. He opens the first movement with a jaunty little march tune that quickly becomes embroiled in complex imitations. Throughout the movement he sets off this march tune against a wealth of varied melodic material — fanfares, stormy passages, singing melodies, pathetic turns of phrase — a kaleidoscope of ideas matching the lively interplay between the piano, strings, and winds. Mozart assigns the piano a number of roles: singer, brilliant soloist, and, when the orchestra takes the principal melodic material, member of the ensemble.

The nineteenth century was truly the age of the solo concerto as the brilliance of tone of both violin and piano encouraged the development of dazzling technical displays. Immense musical difficulties, excitingly conquered by the hero-soloist, astounded and captivated audiences then as they do now. The concertos of Mendelssohn, Liszt, Paganini, and, in the early twentieth century, Rachmaninoff have been test pieces for entrance into the world of the virtuoso. Brahms wrote music just as difficult into his concertos, but with a stronger and more involved eloquence. Brahms’s soloist is declaiming a powerful and deeply conceived message. The figuration in his Violin Concerto in D Major is fiendishly difficult, as if Brahms wrote his concerto, in the words of one contemporary, “against the violin” instead of for it. Example 10 illustrates the extremely difficult figuration that runs through much of that work.

Ex. 10

Virtuoso figuration. Brahms: Violin Concerto in D Major, first movement.

Fugue

Fugue means “flight.” In music it refers to a process in which voices follow each other in imitation. The term also refers to entire pieces written according to this process. A fugue can become very complex, a test for the skilled composer as well as for the performer and listener. Still, its origins are quite simple. We can see them today in such elementary rounds as “Row, Row, Row Your Boat.” By comparing the imitation of a round with that of a fugue, we can get some idea of their similarities and differences and of how they each build their own forms.

First the round. A round is a complete melody that is neatly segmented into sections of equal length. One voice starts alone, then other voices enter in turn at the beginning of each new section. They sing the complete tune several times, then drop out as each finishes the tune after a number of turns. The harmony is simple. When all the sections are going at the same time — stacked as it were (see brackets in Example 11) — the sound is full, consonant, and rich.

Ex. 11

The round. “Row, Row, Row Your Boat.”

A fugue is an open form, of no specified length. Unlike a round, a fugue subject need not be a complete melody; a motive with strong rhythmic-melodic imprint will do. The entries of the voices also differ from those of the round. In the round each voice enters on the same note; in a fugue the second entry transposes the subject to begin on the dominant (V). Here we have opposition of pitches, not reinforcement as in the round. The third and fourth entries reflect this opposition of pitch levels, and the I-V relationship of entries promotes the continuation of the music, rather than a circling around. Another difference: in the round the melody rigidly accompanies itself; in the fugue the counterpoint to each new entry is free of this condition, so the interactions among the voices are left to the inventiveness and skill of the composer.

A set of entries in a fugue is called an exposition. Between expositions the subject may be absent while free counterpoint proceeds. These intervening sections are called episodes. Thus, fugues simply alternate expositions and episodes. Example 12 shows how the opening motive of “Row, Row, Row Your Boat” could be adapted to fugal procedure.

Ex. 12

Fugal procedure of “Row, Row, Row Your Boat”.

A fugue contains at least two or three sets of entries. As each voice enters, those already in motion continue with free counterpoint (i.e., melodic material distinct from the subject yet neatly fitted to it) or one voice may remain silent.

An immense range of options is available within the general limits of key and contrapuntal imitation. Accordingly, of the 24 fugues in Bach’s Well-Tempered Clavier, no two are alike in internal layout. To illustrate some differences, we shall look at two of the best-known pieces from The Well-Tempered Clavier, Fugues nos. 1 and 2.

The first fugue, a very densely woven piece of musical tapestry, is a descendant of a Renaissance genre, the ricercar (“to search”). Hence, the mood is serious and searching. At some points Bach has each voice enter with the subject before the preceding voice has completed its run — a technique called stretto (“narrow”) for its closely spaced action (Example 13). The effect is to increase the intensity of musical movement.

Ex. 12

Fugal imitation. Bach: Fugue in C Major, The Well-Tempered Clavier, Book I.

Bach calls the subject to our attention in an impressive and insistent manner, so that the entire piece projects an impression of substance and importance. In this piece we can hear only two cadences, each very powerful. The first appears about midway in the piece; the second takes the form of a broad area of arrival, extending through the final four measures. Throughout the twenty-seven measures of the fugue, we hear the subject more than twenty times.

In contrast, the second fugue has a much lighter quality. It borrows the rhythm of the bourree, a very popular eighteenth-century dance in quick duple time with a short upbeat. In the fugue’s thirty-one measures, the subject appears only eight times. This fugue has a thin texture; its quality of movement is light and buoyant, and concern with its subject far less serious than that of the first fugue. A very clear sense of punctuation divides the structure into two-measure groups that tend to form symmetrical relationships. Thus, in spite of its skillfully worked-out counterpoint. Bach retains in this fugue the spirit of the dance that was its source.

Free Types

Each of the set forms described so far has its own game plan, which is outlined by keys, sections, and important points of reference. Now, we turn to music that does not have such outlines. Even the names — fantasia, prelude, introduction, recitative — indicate a free-flowing style, one that wanders and changes its mood suddenly.

Generally such pieces create an expectation for a set form. An introduction sets up an expectation for a movement in sonata form, a rondo, or a variation. An operatic recitative leads into an aria. A Bach prelude prepares you for the fugue that will follow. Fantasias also create preparation for fugues. Some fantasias are complete pieces that include both the free and the set forms in alternation. Mozart’s great Fantasia in C Minor includes five parts and proceeds as follows: free, fixed, free, fixed, free (with the final free section set firmly into the home key). Effects of freedom arise from harmonies that seem to shift without a firm footing of key, from stop-and-start motion (often with unexpected changes of style), from brilliant figuration, and from combinations of these procedures. Example 14 shows both the shifting harmonies and the brilliant figuration typical of the fantasia.

Ex. 14

Fantasia figuration. Mozart: Fantasia in C Minor.

The play between set form and freedom is one of the most remarkable and exciting aspects of art music. In most of the music of the eighteenth and nineteenth centuries — symphonies, concertos, chamber music, arias, and choral works — a grand rhythm encompasses firm beginnings, strong middle points, and conclusive endings, along with a freer flow between these points. Indeed, the great Baroque, Classic, and Romantic styles are interminglings of dancelike regularity and fantasialike freedom.