thumb|400px|Early examples of sonata form resemble two-reprise continuous ternary form.
thumb|400px|Sonata form, optional features in parentheses
The sonata form (also sonata-allegro form or first movement form) is a musical structure generally consisting of three main sections: an exposition, a development, and a recapitulation. It has been used widely since the middle of the 18th century (the early Classical period).
While it is typically used in the first movement of multi-movement pieces, it is sometimes used in subsequent movements as well—particularly the final movement. The teaching of sonata form in music theory rests on a standard definition and a series of hypotheses about the underlying reasons for the durability and variety of the form—a definition that arose in the second quarter of the 19th century. There is little disagreement that on the largest level, the form consists of three main sections: an exposition, a development, and a recapitulation; however, beneath this general structure, sonata form is difficult to pin down to a single model.
The standard definition focuses on the thematic and harmonic organization of tonal materials that are presented in an exposition, elaborated and contrasted in a development and then resolved harmonically and thematically in a recapitulation. In addition, the standard definition recognizes that an introduction and a coda may be present. Each of the sections is often further divided or characterized by the particular means by which it accomplishes its function in the form.
After its establishment, the sonata form became the most common form in the first movement of works entitled "sonata", as well as other long works of classical music, including the symphony, concerto, string quartet, and so on.]]
According to the Grove Dictionary of Music and Musicians, sonata form is "the most important principle of musical form, or formal type, from the Classical period well into the 20th century". As a formal model it is usually best exemplified in the first movements of multi-movement works from this period, whether orchestral or chamber, and has, thus, been referred to frequently as "first-movement form" or "sonata-allegro form" (since the typical first movement in a three- or four-movement cycle will be in allegro tempo). However, as what Grove, following Charles Rosen, calls a "principle"—a typical approach to shaping a large piece of instrumental music—it can be seen to be active in a much greater variety of pieces and genres, from minuet to concerto to sonata-rondo. It also carries with it expressive and stylistic connotations: "sonata style"—for Donald Tovey and other theorists of his time—was characterized by drama, dynamism, and a "psychological" approach to theme and expression.
At the end, the music will usually return to the tonic key in preparation of the recapitulation. (On occasion, it will actually return to the sub-dominant key and then proceed with the same transition as in the exposition.) The transition from the development to the recapitulation is a crucial moment in the work. The last part of the development section is called the ': It prepares for the return of the first subject group in the tonic.
Exceptions include the first movement of Brahms's Piano Sonata No. 1. The general key of the movement is C major, and it would then follow that the retransition should stress the dominant seventh chord on G. Instead, it builds in strength over the dominant seventh chord on C, as if the music were proceeding to F major, only to take up immediately the first theme in C major. Another exception is the fourth movement of Schubert's Symphony No. 9. The home key of the movement is C major. The retransition prolongates over the dominant chord on G, but suddenly takes up the first theme in the flattened mediant E major.
A particularly common exception is for the dominant to be substituted with the dominant of the relative minor key: one example is the first movement of Haydn's String Quartet in E major, Op. 54 No. 3.
Occasionally, the retransition can begin with a false recapitulation, in which the opening material of the first theme group is presented before the development has completed. The surprise that ensues when the music continues to modulate toward the tonic can be used for either comic or dramatic effect. An example occurs in the first movement of Haydn's String Quartet in G major, Op. 76 No. 1.
Recapitulation
The recapitulation is an altered repeat of the exposition, and consists of:
- First subject group – normally given prominence as the highlight of a recapitulation, it is usually in exactly the same key and form as in the exposition.
- Transition – often the transition is carried out by introducing a novel material: a kind of an additional brief development. It is called a "secondary development".
- Second subject group – usually in roughly the same form as in the exposition, but now in the home key, which sometimes involves change of mode from major to minor, or vice versa, as occurs in the first movement of Mozart's Symphony No. 40 (K. 550). More often, however, it may be recast in the parallel major of the home key (for example, C major when the movement is in C minor like Beethoven's Symphony No. 5 in C Minor, op. 67/I). Key here is more important than mode (major or minor); the recapitulation provides the needed balance even if the material's mode is changed, so long as there is no longer any key conflict.
Exceptions to the recapitulation form include Mozart and Haydn works that often begin with the second subject group when the first subject group has been elaborated at length in the development. If a theme from the second subject group has been elaborated at length in the development in a resolving key such as the tonic major or minor or the subdominant, it may also be omitted from the recapitulation. Examples include the opening movements of Mozart's piano sonata in C minor, K. 457, and Haydn's String Quartet in G major, Op. 77 No. 1.
After the closing cadence, the musical argument proper is said to be completed harmonically. If the movement continues, it is said to have a coda.
Coda
thumb|upright=1.5|The coda to [[Mozart's Sonata in C Major, K. 309, I, mm. 152–155; last bars of recapitulation also presented for context Using a new theme was a very common way to achieve this, but other resources such as changes in texture, salient cadences and so on were also accepted practice.
No transitions between the first and second subject groups
In some sonata-form works, especially in the Classical period, there is no transitional material linking the subject groups. Instead, the piece moves straight from the first subject group to the second subject group via common-tone modulation. This happens in the first movement of Mozart's Symphony No. 31 and again in the third movement of his Symphony No. 34. It also occurs in the first movement of Beethoven's Symphony No. 1. In the exposition, the first subject group ends on a half-cadence in tonic, and the second subject group immediately follows in the dominant key (without a transition).
Expositions that modulate to other keys
The key of the second subject may be something other than the dominant (for a major-mode sonata movement) or relative major (for a minor-key movement). A second option for minor-mode sonata form movements was to modulate to the minor dominant; this option, however, robs the sonata structure of the space of relief and comfort that a major-mode second theme would bring, and was therefore used primarily for a bleak, grim effect, as Beethoven did with some frequency. Mendelssohn also did this in the first movement of his Symphony No. 3 and the last movement of his Symphony No. 4.
A minor-key sonata form movement can also modulate to the major dominant, as in the first movements of Tchaikovsky's Symphony No. 1 and Brahms's Symphony No. 4.
About halfway through his career, Beethoven also began to experiment with other tonal relationships between the tonic and the second subject group. The most common practice, for Beethoven and many other composers from the Romantic era, was to use the mediant or submediant, rather than the dominant, for the second group. For instance, the first movement of the "Waldstein" sonata, in C major, modulates to the mediant E major, while the opening movement of the "Hammerklavier" sonata, in B major, modulates to the submediant G major, and String Quartet No. 13 in the same key modulating to the flattened submediant key of G major. Tchaikovsky also implemented this practice in the last movement of his Symphony No. 2; the movement is in C major and modulates to the flattened submediant A major. The young Chopin even experimented with expositions that do not modulate at all, in the opening movements of his Piano Sonata No. 1 (remaining in C minor throughout) and his Piano Concerto No. 1 (moving from E minor to E major).
Beethoven began also to use the submediant major with more frequency in minor-key sonata-form movements, as in the first movements of Symphony No. 9, Piano Sonata No. 32, and String Quartets No. 11 and No. 15. The latter case transposes the second repeat of its exposition by a fifth, starting on the minor dominant (instead of the tonic) and finishing on the major mediant (instead of the submediant). The first movement of Richard Strauss's Symphony No. 2, in F minor, modulates to the submediant D major, as do the F minor first movements of Brahms' first clarinet sonata and piano quintet; all three works balance this downward third by moving up to the major mediant (A major) for the key of the second movement.
Rarely, a major-mode sonata form movement will modulate to a minor key for the second subject area, such as the mediant minor (Beethoven Sonata Op. 31/1, i), the relative minor (first movements of Beethoven Triple Concerto and Brahms Piano Trio No. 1) or even the minor dominant (Brahms Piano Concerto No. 2, i). In such cases, the second theme will often return initially in the tonic minor in the recapitulation, with the major mode restored later on.
During the late Romantic period, it was also possible to modulate to remote tonal areas to represent divisions of the octave. In the first movement of Tchaikovsky's Symphony No. 4, the first subject group is in the tonic F minor but modulates to G minor and then to B major for the second subject group. The recapitulation begins in D minor and modulates to F major, and goes back to the parallel F minor for the coda.
left|thumb|Watercolour of [[Franz Schubert, who is known for using three-key expositions]]
Expositions with more than two key areas
The exposition need not only have two key areas. Some composers, most notably Schubert, composed sonata forms with three or more key areas (see three-key exposition). The first movement of Schubert's Quartet in D minor, D. 810 ("Death and the Maiden"), for example, has three separate key and thematic areas, in D minor, F major, and A minor. Similarly, Chopin's Piano Concerto in F minor uses F minor, A major, and C minor in its first movement's exposition. In both cases, the transition is i–III–v, an elaboration of the minor schema of either using i–III or i–v. This is by no means the only scheme, however: the opening movement of Schubert's Violin Sonata in G minor, D. 408, uses the scheme i–III–VI, and the opening movement of Schubert's Symphony No. 2 in B major, D. 125, uses the scheme I–IV–V. The first movement of Tchaikovsky's Symphony No. 5 uses the scheme i–v–VII. An extreme example is the finale to Schubert's Symphony No. 6, D. 589, which has a six-key exposition (C major, A major, F major, A major, E, and G major), with a new theme for each key.
The second subject group can start in a particular key and then modulate to that key's parallel major or minor. In the first movement of Brahms' Symphony No. 1 (in C minor), the second subject group begins in the relative E major and goes to the parallel mediant E minor. It also occurs in the first movement of Beethoven's Piano Sonata No. 8 (also in C minor), except the second subject group starts in E minor before going to E major. The opening movement of Dvorak's Symphony No. 9 in E minor has its second subject group start in the minor mediant G minor and then to its parallel G major. And in the opening movement of his Symphony No. 6 in D major, the first theme of the second subject group is in the relative B minor while the second theme is in the parallel submediant B major.
Modulations within the first subject group
The first subject group need not be entirely in the tonic key. In the more complex sonata expositions there can be brief modulations to fairly remote keys, followed by reassertion of the tonic. For example, Mozart's String Quintet in C, K. 515, visits C minor and D major as chromaticism within the C major first subject group, before finally moving to D major, the dominant of the dominant major (G major), preparing the second subject group in the dominant. Many works by Schubert and later composers utilized even further harmonic convolutions. In the first subject group of Schubert's Piano Sonata in B, D. 960, for example, the theme is presented three times, in B major, in G major, and then again in B major. The second subject group is even more wide-ranging. It begins in F minor, moves into A major, then through B major to F major.
Recapitulations in the "wrong key"
In the recapitulation section, the key of the first subject group may be in a key other than tonic, most often in the subdominant, known as a "subdominant recapitulation". In some pieces by Mozart, such as Mozart's Piano Sonata No. 16 in C, K. 545, or the finale of his String Quartet No. 14 in G, K. 387, the first subject group will be in the subdominant and then modulate back to tonic for the second subject group and coda. This case is also found in the first movement of Beethoven's "Kreutzer" sonata. Schubert was also a prominent user of the subdominant recapitulation; it appears for example in the opening movements of his Symphonies No. 2 and No. 5, as well as those of his piano sonatas D 279, D 459, D 537, D 575, as well as the finale of D 664. Sometimes this effect is also used for false reprises in the "wrong key" that are soon followed by the actual recapitulation in the tonic, such as in the first movement of Haydn's quartet Op. 76 No. 1 in G (false reprise in the subdominant), or the finale of Schubert's piano sonata in A, D 959 (false reprise in the major submediant). A special case is the recapitulation that begins in the tonic minor, for example in the slow movement of Haydn's quartet Op. 76 No. 4 in E, or the opening movement of Haydn's Symphony No. 47 in G major. In the Classical period, the subdominant is the only possible substitute for the tonic at this position (because any other key would need resolution and would have to be introduced as a false reprise in the development), but with the erosion of the distinction between the sharp and flat directions and the blurring of tonal areas true recapitulations beginning in other keys became possible after around 1825.
It is possible for the first subject group to begin in tonic (or a key other than tonic), modulate to another key and then back to tonic for the second subject group. In the finale of the original 1872 version of Tchaikovsky's Symphony No. 2, the first subject group begins in the tonic C major, modulates to E major, then through E major, and then modulates back to tonic for the second subject group and coda. And in the last movement of Schubert's Symphony No. 9 in C major, the first subject group is in the flattened mediant E major, modulates to the subdominant F major and then back to tonic for the second subject group and coda. It is also possible to have the second subject group in a key other than tonic while the first subject group is in the home key. For instance in the first movement of Richard Strauss's Symphony No. 2 in F minor, the recapitulation begins with the first subject group in tonic but modulates to the mediant A major for the second subject group before modulating back to F minor for the coda. Another example is the first movement of Dvorak's Symphony No. 9. The recapitulation begins in the tonic E minor for the first subject group, but the second subject group modulates to G-sharp minor, then through A-flat major before modulating back to the tonic key for the coda. Similarly, in Beethoven's "Waldstein" Sonata, the first subject group is in the tonic C major, then modulates to A major for the first part of the second subject group but quickly goes through A minor to modulate back to tonic for the rest of the second subject group and coda.
Another possibility is both subject groups in the recapitulation going through multiple keys. In the first movement of Schubert's Symphony No. 8, the first subject group begins in the tonic B minor but modulates to E minor and then to F minor. The second subject group starts in the mediant D major before modulating to the parallel tonic B major.
Romantic works even exhibit progressive tonality in sonata form: for example, the second movement 'Quasi-Faust' from Charles-Valentin Alkan's Grande sonate 'Les quatre âges is in D minor, and while the exposition travels from D to the major subdominant G major, the recapitulation begins again in D minor and ends in the relative major F major, and stays there till the end of the movement. Such a scheme may have been constructed to conform with the programmatic nature of the movement, but also fits well with the Romantic penchant for beginning a work at maximum tension and decreasing the tension afterwards, so that the point of ultimate stability is not reached until the last possible moment. (Furthermore, the identification of a minor key with its relative major is common in the Romantic period, supplanting the earlier Classical identification of a minor key with its parallel major.)
Partial or varied recapitulations
In some pieces in sonata form, in the recapitulation, the first subject group is omitted, leaving only the second subject group, like the second movement of Haydn's Sonata Hob. XVI/35, as well as the opening movements of Chopin's Piano Sonata No. 2 and No. 3. It is also possible for the first subject group to be slightly different in comparison of the exposition, like the fourth movement of Dvorak's Symphony No. 9. Another example occurs in the finale of Mozart's string quartet K. 387, where the opening of the first subject group is cut, and in the quintet K. 515, where a later portion of the first subject group is cut. On the other hand, it is also possible for the subject groups to be reversed in order, like the fourth movement of Bruckner's Symphony No. 7, or the first movement of Mozart's piano sonata in D major, K. 311. The second subject group's melody can be different compared to the exposition, like Haydn's Symphony No. 44. Such melodic adjustment is common in minor-key sonata forms, when the mode of the second subject needs to be changed, for example in the opening movement of Mozart's wind serenade K. 388. In rare cases, the second subject theme can be omitted, as in the finales of Tchaikovsky's Symphony. No 1 and his Violin Concerto in D major; in the case of the first symphony, the movement's introductory theme replaces the second subject group.
Truncated sonata form
Occasionally, especially in some Romantic works, the sonata form extends only as far as the end of the exposition, at which point the piece transitions directly into the next movement instead of a development section. One example is Henryk Wieniawski's Violin Concerto No. 2 in D minor. Another example is Fritz Seitz's Violin Concertos for students, where such a truncated sonata form is used ostensibly to cut down on the first movements' length. Sometimes, the third movement of such works is the recapitulation of the first movement (one example being Franz Strauss' Horn Concerto in C Minor), making the entire work effectively a single-movement sonata.
Some Classical slow movements involve a different sort of truncation, in which the development section is replaced altogether by a short retransition. This occurs in the slow movements of Mozart's quartets K. 387, K. 458, K. 465, K. 575, and K. 589. It is also common in overtures, occurring for example in Mozart's overture to Le nozze di Figaro, or Rossini's overture to Il barbiere di Siviglia. This is distinct from a short development, such as in the opening movement of Mozart's Violin Sonata in G major, K. 379.
Another instance of a truncated sonata form has the development section completely omitted altogether, and the recapitulation immediately follows the exposition (even without a retransitional passage). This is known as sonatina form. And it occurs in the second movement of Beethoven's Symphony No. 8. It also happens in the first movement of Tchaikovsky's Serenade for Strings and again in the third movement of his Symphony No. 6.
In concerti
thumb|First page of the autograph manuscript of Mozart's [[Piano Concerto No. 23 (Mozart)|Piano Concerto No. 23]]
An important variant on traditional sonata-allegro form is found in the first movement of the Classical concerto. Here, the sonata-allegro's customary 'repeated exposition' is replaced by two different but related sections: the 'tutti exposition' and the 'solo exposition'. Prototypically the 'tutti exposition' does not feature the soloist (except, in early classical works, in a 'continuo' role), and does not contain the decisive sonata-exposition modulation to the secondary key. Only when the 'solo exposition' is under way does the solo instrument assert itself and participate in the move to (classically) the dominant or relative major. The situation is only seemingly different in the case of Mozart's concerto No. 9, where the soloist is heard at the outset: as the later unfolding of those movements makes clear, the opening piano solo or early piano flourishes actually precede the start of the exposition proper. This presentation is also found in Classical-to-Romantic transition, such as Beethoven's piano concertos No. 4 or No. 5, and Romantic concertos, like Grieg's A minor concerto or Brahms' B major concerto.
A structural feature that the special textural situation of the concerto makes possible is the 'ownership' of certain themes or materials by the solo instrument; such materials will thus not be exposed until the 'solo' exposition. Mozart was fond of deploying his themes in this way.
Towards the end of the recapitulation of a concerto movement in sonata form, there is usually a cadenza for the soloist alone. This has an improvisatory character (it may or may not actually be improvised), and, in general, serves to prolong the harmonic tension on a dominant-quality chord before the orchestra ends the piece in the tonic.
Some may decline the existence of "double exposition" - they would say the first subject theme actually extends far out from the start of the "tutti exposition" to the first subject of the "solo exposition", meaning there is only one exposition.
History
The term sonata is first found in the 17th century, when instrumental music had just begun to become increasingly separated from vocal music. The original meaning of the term (derived from the Italian word suonare, to sound on instrument) referred to a piece for playing, distinguished from cantata, a piece for singing. At this time, the term implies a binary form, usually AABB with some aspects of three part forms. Early examples of simple pre-Classical sonata forms include Pergolesi's Trio Sonata No. 3 in G major. Their study focuses on the normative period of sonata practice, notable ones being the works of Haydn, Mozart, Beethoven, Schubert, and their close contemporaries, projecting this practice forward to development of the sonata-allegro form into the 19th and 20th centuries.