Rondo-Sonata, Rondo or Sonata-Rondo (coda)?

The Structure of Mozart's Piano Sonata K309 Finale

by Nicholas Donlevy

Mozart's Sonata in C major K309 was composed in Mannheim in October of 1777. Thanks to a letter written by Mozart it is known that the piece was improvised in a performance and later committed to paper for publication. In this letter Mozart 'writes of how he "played…all of a sudden a magnificent sonata in C major, out of my head, with a rondo at the end - full of din and sound". It's outer movements became the sonata K309.'1

Click to hear the rondo finale. (MIDI 32.7Kb)

Mozart, in this quote, calls his finale a rondo, but this term can be rather ambiguous. According to sources a rondo is any movement or work which contains a recurring refrain, alternating with a number of episodes, and most claim that it must begin and end with the refrain material. Some ambiguity arises in the number of refrains necessary to constitute a rondo. Some sources, such as Green2 and Goetschius3 suggest that only two occurrences of the refrain are necessary, whereas others such as Berry4 claim that at least three recurrences of the refrain are required. The rondo form is therefore open to many variations in structure depending on how the refrain and intermediary episodes are treated.

All sources, however, seem to agree that in the Classical era the rondo was most often used as one movement within a larger work, most commonly the finale. These rondos also tended to favour one variant of the rondo form, as illustrated by Green's dubbing it the Classical rondo form5. The structure that is most common is as follows:

Figure 1

The basic structure of the final rondo movement of Mozart's K309 is:

Figure 2

Figure two shows that this movement agrees with the usual form of the Classical rondo with one major exception - Mozart has omitted the third statement of the refrain (A). A possible reason for this omission will be discussed below.

This type of rondo has often been discussed in terms of ternary structure. Green, in agreement with Schoenberg6, groups the sections of the form into three parts:

Figure 3

and so he 'perceives an over-all composite sectional ternary structure, part three being a partly transposed version of part one, both surrounding a central part.'7 He also says that this view is supported by the fact that section C receives individualised treatment. The greater contrast of section C in key area, material and often length is a cited as a feature of this rondo form in many sources.

Heinrich Schenker views rondo forms as a combination of a number of ternary structures.8 He would group the elements of the form into three interlocking tripartite sections, the final refrain of one ternary structure forming the initial refrain of the next:

Figure 4

These analyses of the rondo form, however, seem to falter when applied to the movement in question. The removal of the third A section means that part three of Green's model is no longer the same as part one and therefore the form can no longer be seen as one large ternary structure. The same problem also puts Schenker's model into question as the missing A section removes the last part of the second ternary structure and the initial refrain of the third. The removal of the A section in fact destroys the arch form of this rondo design that Berry says 'is more clearly suggested…than in any other traditional musical form'9, and on which the above two models rely.

It is however not only the removal of the third refrain that problamatises these models but also the dispersion of thematic material throughout the movement. In its earlier forms the rondo was a simple, sectional piece in which the parts of its structure were clearly defined. Later, however, in the hands of the classicists this was no longer the case; Mozart 'moved from a simple, sectional structure to a complex, integrated form into which he built surprise and variety, and within which he attempted to offset and even exploit the regularity inherent in the traditional layout.'10 The addition of complex transitions and re-transitions between the sections of the rondo facilitates the greater integration and dramatic momentum of the form. Greater unity is also often achieved through thematic relationships throughout the structure.

In order to maintain the textbook definition of the rondo form and to perpetuate the sectional appearance of the form, most theorists will group the various transitory passages under the umbrella of the episode so that any material that cannot be said to belong to the refrain therefore belongs to the episode. In fact the very nature of the transition is to take the music from one section to another, which would suggest that they belong to neither but are situated between the sections. Here, therefore, the transitions will be treated as separate intermediary passages, belonging neither to refrain nor to episode but which, in effect, do not deter from the overall impression of the rondo structure.

In the movement in question Mozart uses a large amount of different thematic material that reappears throughout. Figure 5 shows the divisions of the structure, including transitions (t) with lower case letters denoting the subdivisions of thematic material on which the various sections are based.

Figure 5

This chart illustrates the degree of complexity that Mozart invests in the rondo and the extent to which it is no longer the simple form of distinct sections but contains passages not merely designed for transition but constructed out of the episodic thematic material so as to play a part in the integration of that material throughout the movement.

This interesting use of thematic material from the episodes in the transitory passages is not only to disperse that material but in using material from a specific episode, or introducing an entirely new theme the transition can take on a double function. This second function becomes important when we consider that this is not just a typical Classical rondo but a sonata-rondo, a form that it is said Mozart himself invented.

As the name suggests the sonata-rondo is a hybrid form, which evinces characteristics from both the rondo and the sonata. However, as Malcolm Cole has noted, the 'specific components of a sonata-rondo have been, and remain, the subject of disagreement.'11 Many sources differ in their opinions of what features a structure must possess in order to qualify as a sonata-rondo.

The form previously discussed, which Green classes the Classical rondo would, by some, be classed a sonata-rondo. Green only does so if a development section substitutes the second episode C. Schoenberg also views a development section as a necessary requirement of sonata-rondo form. Others however have varying views as to the importance or frequency of developmental C sections in the sonata-rondo. Paul Fontaine comments on 'a general lack of development in the middle … episode'12, Cole states that it is a possibility13, Charles Rosen says it is usual14 and Berry frequent15. The majority however seem not to view development as a necessity, but place more importance on the recurrence of episode B in the tonic key. This feature causes the third episode and its preceding refrain to reflect the sonata-style recapitulation of the initial refrain and episode with the tonal relationships that are so important to the sonata form. The classical rondo structure would therefore fit the criteria of a sonata-rondo form.

Another area of disagreement in relation to sonata-rondo form is in the classification of the overabundant A sections. The A section appears more often in the sonata rondo than it would in a true sonata form and theorists have taken differing approaches to overcome this problem. Both Green16 and Fontaine17 group the sections of the sonata-rondo into a sonata structure as follows:

Figure 6

In this model the second and the final refrain are designated as part of the exposition and the recapitulation although they would not appear in a true sonata. Fontaine recognizes this and comments that this is one of the fundamental dissimilarities between the sonata-rondo and the true sonata. Green does not acknowledge the difference.

William Caplin, however, proposes a different model that attempts to better explain the superfluous refrains, bringing the structure to closer proximity with the sonata form:

Figure 7

In his model Caplin attempts to explain the presence of the second refrain in relation to the sonata form when he states that this refrain 'can be heard to mark the repetition of a sonata exposition. Thus it is only when the music begins to depart from the plan laid out in the exposition that the listener can confirm an interpretation of Rondo form.'18 His explanation of the final occurrence of the refrain however is less satisfactory. It is claimed that 'unlike a regular sonata, the coda is a required element of sonata-rondo, because that section includes the final return of the main theme'19 He admits that the final refrain and its relation to the coda are problematic and, due to a lack of consistent relation ship between the two, takes his cue from the sonata form in stating that 'the coda of a sonata-rondo can be said to start at the same place as it does in a regular sonata, namely, at the point where the music of the recapitulation stops corresponding to the exposition.'20 In this way Caplin explains away the problem of the final statement of the refrain by situating it always within the coda. Although some sonata-rondos do undeniably eschew the final refrain, including material from the A section in the coda to stand in its place this explanation does still seem problematic. If a coda is supplementary material, superfluous to the necessary structural material of a form, then placing the final A section within the coda raises questions in relation to the theory that a rondo form must end with a statement of the refrain.

This problem could provide one possible answer to the previously posed question - why does Mozart, in the K309 rondo finale, omit the third statement of the refrain? This omission allows an interpretation of the form in relation to sonata structure that does not encounter these problems with the final refrain. Rosen suggests that we might see the repeat of the B section and the final statement of A as a reversed recapitulation, that is, 'playing the second group first, then the first theme and then the closing theme.'21 This would mean that the movement would fit nicely into Caplin's model of the sonata-rondo's sonata structure:

Figure 8

This model of the movement's structure also enables us to examine the second function of the thematic dispersion throughout the movement, and to explain Mozart's reasoning in choosing the thematic material of the transitions. The transitory material works with the thematic material of the episodes to create the sonata structure of this sonata-rondo movement:

Figure 9

This chart shows how the sonata features of the form help to create a secondary momentum through the sections of the sectional rondo form, working with the thematic disposition to create a narrative thread through the movement and smoothing out the disjointed nature of the rondo form.

This model, however, forces the question why did Mozart omit the third refrain and reverse the recapitulation when leaving out the final refrain would have left the recapitulation in the usual order? A possible answer might be that the movement is not only a sonata but also a rondo and that rondos must end with the refrain. This argument will not stand however when we consider, as previously mentioned, that in many works the final refrain is omitted, and material from A placed in the coda, as this rondo displays, is taken as sufficient. Indeed in some of Mozart's own sonata-rondos he does displace the final refrain with a coda based on the same material. In fact Caplin notes that 'if Mozart retains refrain 3 in his sonata-rondo forms, then he usually eliminates refrain 4, although its opening motives may pervade the texture of the coda.'22

At this point a detailed examination of the piece and the dual function of its sections might serve to answer this question, and also to trace how the narrative of the movement is constructed and serves to keep the music moving throughout, whilst aiding in the integration of the whole.

The first section of the movement (mm. 1-19) constitutes the opening refrain of the rondo form (A) or the main theme of the exposition in sonata form (a). This section is a typical textbook rondo refrain (see W. Renwick's explanation). It is a complete two-phrase binary form in itself, it is in the tonic key of C major throughout and closes with a perfect authentic cadence onto beat one of measure 19. On each recurrence of the refrain it appears in the same form with minor ornamentation, apart from the last three measures which are modified on each appearance. This modification is used each time to subtly alter the style of the music toward that of the subsequent transition therefore facilitating a smooth movement into the next passage.

This modification of the final three measures of the refrain also helps to answer a question arising from the application of ternary ideas to the rondo form. If, as Schenker suggests, the form is composed of a number of ternary structures, the question arises: why does the music not come to a halt at the end of each of these ternary sections? Indeed if the refrain is a closed, self contained structure in and of itself, and it can be used to end the entire work, why does the work not end after its first statement? This change in style in the last three measures of the refrain, each time accompanied by an increase in rhythmic and harmonic movement, ensures that, although the section is coming to a close, the music does not feel like it is coming to an end but that something else will follow.

Although the refrain is closed, deciding exactly where it ends is not as easy as the theory might suggest. This is due to the effect of the following transition. This section (mm. 19-39) functions merely as a transition in both the rondo (from A to B) and the sonata (from main theme to subordinate theme) elements of the form. At its outset, however, it does not behave as a transition would be expected to; it sounds more like an ending gesture, containing perfect cadences. This string of perfect cadences at the end of the A section make pinpointing the end of A more difficult. When looking at the other occurrences of A its end becomes obvious as this transitory passage does not occur, but when listening to the piece its conclusion is not so clear. After its closing beginning, this section moves away into what is more recognisably a transition, taking the music into the dominant key of G major for the next section.

Green, in agreement with many theorists, states that 'the chief task of the first episode is to express a contrasting key usually V…this may be accomplished without definite melody by the use of scales, arpeggios, or figuration'23 and this is exactly what this section does. It acts as B for the rondo and can be further broken down into two smaller thematic sections c and d, which act as the subordinate themes for the sonata. Both themes are highly figurative with very little melodic writing. Caplin suggests that 'the subordinate-theme group tends to be …highly expansive in relation to the main theme'.24 The section is also intended to set up a contrast with the refrain. The B section is the longest of this movement and is highly dramatic in relation to the refrain, with greater chromaticism and more adventurous harmonies including diminished seventh chords and touches of the minor key.

This section also seems to introduce the element of surprise. The few melodic fragments that the section contains are written with a piano dynamic but are soon interrupted with bursts of forte, chromatic figuration. Thematic section d also features an inverted dominant pedal written in repeating demisemiquaver octaves and marked forte. This works its way to a deceptive cadence followed by three measures of a sweet, piano melodic sequence, only to be suddenly interrupted by the recurrence of the inverted pedal. The overall effect of the B section is to create high drama with music that fits well Mozart's description 'full of din and sound'. The section could hardly be more contrasting to the music of the graceful refrain to which, with the aid of a re-transition, it must now return.

This transition (e) follows on from the deceptive cadence of B in measure 77 and continues into A at measure 92. Similar to the initial transition (b) the music begins with a feeling of closure indeed, along with re-transition to the refrain, that is the other function of this section - the closing theme of the subordinate-theme complex. Once again however this passage continues to a chordal transition back into the home key and elides with the first note of the refrain.

The first recurrence of the refrain takes the same shape as its first appearance with minor ornamentation and the first transformation of its last three measures reflect the style of the inverted pedal point passage from d which is used in the following transition. In the sonata form this refrain is seen as the beginning of an incomplete repetition of the exposition. The following short transition is just that, merely a transition in both the rondo and sonata elements of the form. The choice of material from the B section for this transition is interesting however and could be seen to serve two purposes. The following C section is similarly lacking in dramatic energy to the refrain and, contrary to the theory, does not provide much contrast with it. The use in the refrain of this material from d - arguably the most dramatic passage of the movement - serves to inject energy between these two more docile themes. The d material also has a second interesting role. It could be seen as a summary of the entire B section standing in the place of the repetition of the subordinate-theme complex that would usually occur there in true sonata form.

With the transition having moved to the subdominant key of F major, the music proceeds into the second episode C (measures 115-137). The second episode is where opinions differ as to the necessity of developmental material in the sonata-rondo, with the majority view that it may be present but is not a prerequisite. At first glance this appears to be an interior theme without development and Rosen intimates as such when he says that this movement 'must be classed as a sonata-rondo although there is no development.'25 On closer inspection however the theme of this episode could be seen to bear some resemblance to that of the refrain.

If we examine the voice leading of the opening motive of both the refrain and episode C it can be seen that the motive from C appears to be an inversion of that from A:

Figure 10

Hearing the two motives played in succession, with the second transposed into C major, highlights the connection.

Click to hear a midi file of this example

Although there is this relation of motivic material episode C does not really behave as a sontata development section. The motive could be seen as a development of that from A but it is not developed any further. Also the section does not display the usual roaming tonality of a developmental passage but is tonally static, remaining in F major throughout. The section is essentially a closed, interior theme although the motivic relationship could be seen as a nod toward the developmental section that it represents in sonata form. Episode C is then followed by the recapitulation of sonata form. This is where the refrain would traditionally return for a recapitulation in the usual order. Here, however Mozart chooses to dispense with the refrain, reversing the subordinate themes and the main theme. An explanation for this choice has been touched upon before. Between the second refrain and episode C Mozart inserted a short, four measure transition based on the material from d. It was intimated that one reason for choosing this material would be to separate the static and less dramatic A and C sections. The same could apply at this point. In fact with only those four short measures to create any real drama in the last 43 measures, another 18 measures of static refrain would not be desirable. In reversing the recapitulation and omitting the third occurrence of the refrain rather than the last Mozart returns to the drama and movement of the B section in order to sustain the momentum of the movement. In some of his sonata rondos Mozart does in fact retain the third refrain and omit the last. It would be interesting to see whether the C sections of these works are of a more developmental and dramatic nature.

The return of the B section, as in its first occurrence, begins with the thematic section c. Here however, the section begins with what was previously its ending. Measures 137-141 are an extended version of mm. 48-51 and are altered slightly so as to act as a transition from the F major of episode C back to the home key of C major for the recapitulation of the subordinate-themes. This reversal of the c material is due to the fact that these measures are much better suited to a transitory function than is the music that previously started the section. With the transition to the home key complete the music proceeds through the recapitulation of the subordinate themes of section B, now in the tonic.

As the section comes to an end, however, the music of d is altered and greatly extended into a long, figurative transitory passage. At this point the movement, the subordinate themes have been stated in the tonic key and a return of the refrain is required, also in the tonic key. As Percy Goetschius notes, 'it is evident that the transition here must pursue a course widely different from that of the ordinary transition'26. It is possible to move directly from the episode to the refrain without transition as they share the same tonal center, but this will not suffice for the artistic sensibilities of most composers and therefore 'the opposite course is generally adopted: Instead of shortening, or omitting, this transition is made longer than before, so as to admit of getting away from the principle key, and returning to it.'27 This is surely the case in the extended transitory passage extrapolated from the end of d in measures 179-188.

The transition once again elides beautifully into the opening of the final refrain. This recurrence of A is once again identical except for yet more ornamentation and the last three measures. These measures once again smooth the passage into the transition, this time taking up a triplet rhythm to reflect that of the c material used for the following transition. This short, three measure transition once again uses the material from the end of the original c thematic section; that which was so suited to transition that it was brought to the beginning in its second appearance. In the rondo scheme of the movement this passage is included in the coda, which starts as soon as the final refrain is complete. In sonata form however the transition is leading to the closing theme of the subordinate-theme complex, still part of the reorganised recapitulation and therefore not yet part of the coda.

Thematic section e then follows to complete the recapitulation and at measure 221 the coda of the sonata scheme begins. In the coda Mozart places a recurrence of theme b (mm. 234-243). At its first appearance after the initial refrain b acted as a transition but began with a closing feel. Here, however, the transitory aspect is ejected and the passage fully takes on its closing nature with a large cadential extension. As the theme has not reappeared since its first sounding, this is the ideal place for its recurrence where it could act as the closing theme for the entire piece.

Before the occurrence of this closing theme, however, the coda contains a three measure passage of the inverted pedal music from d (mm. 225-227) and a passage in triplet rhythm that recalls theme c (mm. 228-233). These sections serve once again to insert drama and reinvest the music with momentum, again adding an element of surprise and preventing the closing theme from ending the piece. Theme e is a closing theme as is theme b, and so the d and c sections serve to keep the music moving after e until b arrives to close.

Closing theme b does not, however, end the work. It sets up a large cadential passage with a number of perfect authentic cadences, but when it reaches the point of climax and complete closure it is left hanging and a strange recurrence of theme a closes the piece. This a theme is slightly altered with a bizarre Alberti bass two octaves below the melody giving a tonic pedal effect, and B flats which add a touch of the subdominant to the passage. The overall effect is of a strange echo of the refrain theme. Whether this ending is to make up for the missing A section or an acknowledgement that a rondo should end with the refrain we cannot tell, but this is definitely a very strange passage with which to end a work.

This examination of the sonata-rondo illustrates the functionality of each section, indeed the dual function of some sections. It also serves to explain Mozart's choices in the positioning of thematic material and how these choices along with the combination of sonata form with rondo structure, create a narrative thread within the music propelling it forward and transforming the static, sectional quality of the rondo structure into a more dramatic form with momentum.

The combination of rondo and sonata forms in one movement such as this raises the question of whether the structure is more rondo or more sonata. This movement evinces differences from the true form of both these structures. It differs from sonata form in the incomplete repetition of the exposition and in its not-quite-development section. The differences from the rondo lie in the missing repeat of the refrain and the lack of independence in episode C. In a movement that possesses all occurrences of the refrain the form might be seen to be more of a rondo than a sonata. This movement, however, reflects the textbook requirements of both forms but does not entirely fulfill either. The form then cannot be said to be more one thing than the other, and Mozart appears to have developed his sonata-rondo form into a true hybrid, reflecting both origins equally.


1. "Mozart: Piano Sonata in B-flat K333, first movement" in Edexcel A Level Syllabus - Analysis [book on-line] (Edexcel, 2001, accessed 05 December 2001); available from; Internet.(back)

2. Douglass Green, Form in Tonal Music - An Introduction to Analysis, (New York: Holt, Reinhardt and Winston, Inc., 1965), 153. (back)

3. Percy Goetschius, The Larger Forms of Musical Composition, (New York: G. Schirmer, 1915), 93.(back)

4. Wallace Berry, Form in Music, (New Jersey: Prentice Hall, 1976), 122.(back)

5. Ibid Green, 156.(back)

6. Arnold Schoenberg, Fundamentals of Music Composition, ed. G. Strang and L. Stein (London: Faber and Faber, 1967), 196.(back)

7. Ibid Green, 161.(back)

8. Heinrich Schenker, Free Composition (Der freie Satz), trans. Ernst Oster (New York: Longman, 1935), 141.(back)

9. (back)

10. Malcolm Cole, "Rondo", The New Grove dictionary of music and musicians, 2nd ed., ed. Stanley Sadie; exec. ed. John Tyrrell, (New York: Grove, 2001) XVI, 174.(back)

11. Ibid Cole, 175.(back)

12. Paul Fontaine, Basic Formal Structures in Music (New York: Appleton-Century-Crofts, 1967), 167.(back)

13. Ibid Cole, 175.(back)

14. Charles Rosen, Sonata Forms (New York:W. W. Norton, 1980), 126.(back)

15. Ibid Berry, 241.(back)

16. Ibid Green, 240.(back)

17. Ibid Fontaine, 168.(back)

18. William Caplin, Classical Form (New York, Oxford, 1998), 237.(back)

19. Ibid Caplin, 235.(back)

20. Ibid Caplin, 239.(back)

21. Ibid Rosen, 126.(back)

22. Ibid Caplin, 239.(back)

23. Ibid Green, 157.(back)

24. Ibid Caplin, 233.(back)

25. Ibid Rosen, 126.(back)

26. Ibid Goetschius, 141.(back)

27. Ibid Goetschius, 141.(back)

© Copyright 2001 by Nicholas Donlevy.