In the works of his mature series, Mozart created a unique conception of the piano concerto that attempted to solve the ongoing problem of how thematic material is dealt with by the orchestra and piano. With the exception of the two exceptionally fine early concertos
K. 271 (Jeunehomme) and
K. 414 (the "little A major"), all of his best examples are from later works. Mozart strives to maintain an ideal balance between a
symphony with occasional piano solos and a virtuoso piano
fantasia with orchestral accompaniment, twin traps that later composers were not always able to avoid. His resulting solutions are varied (none of the mature series is really similar to any of the others structurally on more than a broad level) and complex.
First movement structure The form of Mozart's piano concerto first movements has generated much discussion, of which modern instances were initiated by the highly influential analysis provided by Tovey in his
Essay. In broad terms, they consist of (using the terminology of Hutchings): •
Prelude (orchestra) •
Exposition (piano, plus orchestra), ending in a trill in the dominant (for major key concertos) or the relative major (for minor key concertos) • First
Ritornello (orchestra) • Middle Section (piano plus orchestra) •
Recapitulation (piano plus orchestra) • Final Ritornello (orchestra, but always including a piano
cadenza). This structure is rather easy to hear when listening, particularly because the ends of the exposition and recapitulation are typically marked with
trills or shakes. It is tempting to equate this structure with
sonata form, but with a double exposition; so • Prelude = 1st exposition • Exposition = 2nd exposition • Middle section =
development • Recapitulation + final Ritornello = Recapitulation (piano concerto section first, sonata form section second). However, while there are broad correspondences, this simple equation does not really do justice to the Mozartian scheme. For example, the piano concerto may well not include a well-defined second group of subjects in the prelude; and in particular, does not include a definitive
modulation to the
dominant in this section, as might be expected from sonata form, even though Mozart feels free to shift the sense of tonality around in this and other sections. The reason for this, as Tovey remarked, is that the purpose of the Prelude is to generate a sense of expectation leading towards the piano entry, and this must come from the music itself, not just from the title on the top of the page. If a complete sonata form were imposed on the Prelude, then it would take on a life of its own, so that when the piano entry occurs, it would be rather incidental to the overall structure. To express it in another way, in sonata form, the first group of subjects is linked to and generates an expectation of the second group, which would tend to detract attention away from the piano entry – a point that, as Tovey points out, was only grasped by
Beethoven rather belatedly. Conversely, in the Mozartian concept, the piano entry is always a moment of great importance, and he varies it considerably from concerto to concerto. The only exception to this rule is the dramatic intervention of the piano in the second bar of the
Jeunehomme Concerto, which is, however, minor enough not to disturb the overall structure. Rather than the Prelude being a "preliminary canter" (Hutchings) of the themes of the concerto, its role is to introduce and familiarise us with the material that will be used in the
ritornello sections, so that we get a sense of return at each of these. Technically, therefore, the ritornello sections should only include themes that are introduced in the Prelude. In practice, however, Mozart allows himself to sometimes vary even this rule. For example, in
Piano Concerto No. 19, the first ritornello introduces a new theme, which, however, plays only a minor linking role between the restatements of the first theme. The prelude is invariably rich in
thematic material, with as many as six or more well-defined themes being introduced. However, the concertos fall into two rather marked groups as to what sort of themes they possess. The most popular concertos, such as Nos.
19,
20,
21 and
23 tend to have well-marked themes. However, another group, such as Nos.
11,
16,
22, and
27, the themes are less marked, and the overall effect is of
homogeneity. As Mozart's art progressed, these themes sometimes become less
strophic in nature, i.e., he binds them together into a more unified whole. In addition to the ritornello thematic material, Mozart's
mature concertos nearly all introduce new thematic material in the piano exposition, the exceptions being
K. 488 in A major, which, however, follows an unusual course after this, and
K. 537. Hutchings recognises these by labeling ritornello themes A, B, C etc., and expositional themes x, y etc. Mostly these are first introduced by the piano; but sometimes (e.g., theme y of
No. 19) the orchestra plays this role. Sometimes the exposition starts with one of these new themes (in piano concertos Nos.
9,
20,
22,
24, and
25), but the exposition can also start by restating one of the prelude themes. In addition to the preludial and expositional themes, the exposition typically contains various free sections that show off the piano; but, contrary to the popular conception of the piano concerto, and to how it developed in the nineteenth century, these sections are not merely empty displays, but rather, short sections that fit into the overall scheme. The middle sections, as in much of Mozart's symphonic output, are typically short and rarely contain the sort of development associated with, in particular, Beethoven. In other words, Mozart normally generates his middle sections by shuffling, condensing and modulating his thematic material, but not by taking a simple theme and genuinely developing it into new possibilities. However, as is the case with all generalisations involving his piano concertos, this can be overstated: the middle section of
No. 25, for example, can be described as being a genuine development. In other concertos, such as
No. 16, there is no such thing. Mozart's themes are cunningly employed, so that they fit together in various ways. Despite the formal advances in the prelude, the themes are often later used in different orders, so that a scheme of a prelude ABCDE might later become ABADA or something else. Some of the so-called "ritornellic" material of the prelude might indeed never appear again or only appear at the end. For example, in
Piano Concerto No. 19, theme C never appears again, while E and F only appear to close the entire movement. This flexibility is of particular importance in the recapitulation, which, though it invariably commences with a restatement of the first preludial theme, is no mere repetition of the preludial themes. Rather, it condenses and varies them so that the listener is not tired by simple reproduction. The genius of Mozart's mature movements, therefore, is to be able to manipulate a mass of thematic material without compromising the broader scale conception; and the listener, rather than being given the impression of "fiddling" with all the themes, instead is left with the ritornellic impression: Mozart truly uses "art to conceal art". One further point of great importance is the interaction between piano and orchestra. In the earlier concertos, such as the not totally successful
No. 13 in C major, and even more so, perforce, in the concertos for two and three pianos, the interaction between the two is limited, but the later concertos develop the subtle relations between them to a high degree; for example, in
No. 16, K. 451. His later concertos are truly described as concertos for "piano and orchestra" rather than the more obviously "piano" concertos of the nineteenth century (e.g., that of
Grieg etc.). Because Mozart was developing the form of his concertos as he wrote them and not following any preconceived "rules" (apart, presumably, from his own judgement of taste), many of the concertos contravene one or other of the generalisations given above. For example,
K. 488 in A major lacks new expositional material, and "merely" repeats the preludial material; further, it effectively merges the first ritornello and the middle section, as does
K. 449 in E. Several of the later concertos do not hesitate to introduce new material in the supposedly "ritornellic" sections, such as in K.
459,
488, and
491, or, indeed, in the middle section (K.
453,
459, and
488).
Second movement structure , c. 1780. The medallion on the wall is of Mozart's mother. Mozart's second movements are varied, but may be broadly seen as falling into a few main categories. Most of them are marked
Andante, but he himself marked at least the poignant
F minor (K. 488) one
Adagio, presumably to stress its pathetic nature rather than to dictate a particularly slow speed. Conversely, the slow movement of the sunny
No. 19 in F major is marked
Allegretto, in keeping with the mood of the entire concerto. Hutchings gives the following list of movement types (slightly modified): • K. 175:
Sonata form • K. 238:
Aria-sonata • K. 242: Sonata • K. 246: Aria • K. 271: Aria • K. 365: Binary dialogue • K. 413: strophic binary aria • K. 414: strophic binary aria • K. 415:
Ternary with
coda • K. 449: strophic binary aria • K. 450:
Variations with coda • K. 451:
Rondo • K. 453: Aria (Sonata) • K. 456: Variations • K. 459: Sonata (but without development) • K. 466:
Romanza (Rondo, marked Romance without further Tempo Indication) • K. 467: Irregular • K. 482: Variations • K. 488: Ternary • K. 491: Romanza (Rondo) • K. 503: Sonata without development • K. 537: Romanza • K. 595: Romanza Girdlestone puts the slow movements into five main groups:
galant,
romance,
dream,
meditative, and
minor.
Third movement structure Mozart's third movements are generally in the form of a
rondo, the customary, rather light structure for the period. However, two of his most important finales, that to K.
453, and to K.
491, are in
variation form, and they are both generally considered among his best. In addition, three more concertos, K.
450,
451 and
467 can be regarded as being in
rondo-sonata form, with the second theme modulating to the
dominant or
relative major. However, the simple refrain-episode-refrain-episode-refrain structure of a rondo does not escape Mozart's revising attentions. The difficulty for Mozart with the typical rondo structure is that it is naturally
strophic; i.e., the structure is divided into a series of highly differentiated and distinct sections. However, such a structure does not lend itself to creating an overall unity in the movement, and Mozart thus attempts various ways (with greater or lesser success) of overcoming this problem. For example, he may have complex first themes (
K. 595),
contrapuntal treatment (
K. 459), or rhythmic and other variation of the theme itself (
K. 449). In general, Mozart's third movements are as varied as his first movements, and their relation to a "rondo" is sometimes as slender as having a first tune (refrain) that returns.
Similar works by other composers Mozart's large output of piano concertos put his influence firmly on the genre.
Joseph Haydn had written several keyboard concertos (meant for either harpsichord or piano) in the earlier galant style, but his last keyboard concerto,
No. 11 in D, is much more obviously Mozartian, having been written considerably later and concurrently with Mozart's output.
Joseph Wölfl contributed several piano concertos shortly after Mozart's death that also clearly showed Mozart's influence.
Beethoven's first three concertos also show a Mozartian influence to a somewhat lesser extent; this is also true of
Carl Maria von Weber,
J.N. Hummel,
John Field, and others. ==Performance considerations==