Mozart: Piano Sonata No.1 in C major, K.279 Analysis


First Movement (Allegro)

Form: Sonata Form. C Major. 

Mozart Piano Sonata No.1 in C major, K.279 Analysis 1


Bars 1-5: First Subject in Tonic. The first subject is very short. It consists of two three bar phrases which overlap; the second phrase is a repetition of the first.

Bars 5-16: Bridge-passage or Transition. With the exception of an occasional passing touch into other keys, the passage is entirely in the key of C major, in which it ends on a half-cadence, Bar 16.

Bars 16-38: Second Subject in A minor and G major (dominant). The second subject starts in an unusual key; it is divided into two sections. The first section (Bars 16-31) opens with a two-bar phrase in A minor (the relative); this phrase is immediately repeated one degree lower in G major – the usual key of the dominant – in which key the subject continues to the close. Bars 22-24 form a descending sequential passage – repeated modified in Bars 24-25; the whole section is, in fact, lengthened by numerous repetitions; it ends on a perfect cadence, Bar 31. The second subject (Bars 31-38) consists entirely of cadential repetitions and extensions.


Bars 39-57: The development starts in G minor with a passage founded on the opening bar of the first subject in combination with the semiquaver (sixteenth note) figure found in the second section of the second subject, it passes from G minor, through the keys of D minor, and C major, to A minor – to the latter, through the chord of the Neapolitan sixth, Bar 44. Bars 45-47 form a short modulating sequence, probably suggested by the descending scale figures, Bar 22-23, and passing through the keys of A minor and G minor to F major. At each repetition of the semiquaver figures the parts are inverted. Bars 48-51 are reminiscent of the transition, and are followed by a short passage on G (dominant of C major), worked on a variation of the figures from the opening bar of the firs subject, and ending with a scale passage which leads into the recapitulation of this subject, Bar 58.


Bars 58-62: First Subject in Tonic (unaltered).

Bars 64-69: Bridge-passage (shortened and modified). The transition reappears modified, and shortened by the omission of part of the original passage.

Bars 70-100: Second Subject (lengthened) in D minor and C major (tonic). The first section (Bars 70-92) of the second subject is much lengthened. It should be noted:

  • That the first phrase is in D minor, which corresponds to the key of C major (the tonic) as, in the exposition, A minor corresponds to the key of G major (the dominant).
  • That the phrase commences with reversed accents (compare with Bar 16), but, that by the interpolation of an extra half-bar, it ends with the accents in the their original positions.
  • That this extra half-bar has an exactly opposite effect on the repetition of the phrase which immediately follows; the repetition commencing with the accents as original written and ending with them again reversed. Naturally the forgoing transposition of the accents also affects the following phrase, Bars 74-78, causing it also to reappear with accents reversed.

One other point to be noticed is that the additional passage (Bars 82-86), which is here introduced into the second subject, is founded on the bars of the original transition which have just been omitted in the recapitulation of that passage – the last part being an exact repetition. The second section (Bars 92-100) is slightly lengthened at the end to emphasize the final cadence.


Second Movement (Andante)

Form: Sonata Form. F Major. 

Mozart Piano Sonata No.1 in C major, K.279 Analysis 2

It is somewhat unusual in sonatas for the slow movement to be written in unabridged sonata-form, and still more so, as in this instance, for all movements to be in the same form. (See however, No. 5, in G major. Sonatas Nos. 8, 13, and 15 also contain movements in this form.)


Bars 1-6: First Subject in Tonic. The first subject is a sentence of six bars, consisting of three two-bar phrases. In the treble it ends of the first beat of Bar 6, the harmony, however, carrying it on till the second beat in the bass.

Bars 6-10: Bridge-passage or transition. The transition passes transiently through B flat major to C major, in which key it ends on an inverted cadence.

Bars 11-26: Second Subject in C major (dominant). The second subject commences with a motive repeated three times to an accompaniment which, each time varying slightly, forms a sequence in the upper of the two parts. By the elision of a bar in the responsive phrase, the sentence is first contracted to seven bars; it is then extended to sixteen bars by a lengthened and varied repetition of the same phrase. The inversion of the parts between Bars 14 and 17 should be noted.

Bars 26-28: Codetta. But for the fact that, at the end of the movement, the coda separates these three bars from the second subject, it would be hardly necessary here to consider them apart as a codetta.

Double bar and repeat. Note the double bar and repeat marks. As a general rule, in the comparatively few instances in which unabridged sonata-form is employed in slow movements, the exposition is not repeated for even followed by a double bar. It is therefore the more interesting to note that in the various slow movements in his pianoforte sonatas written in this form, Mozart has each tome closed the exposition with both double-bar and repeat marks.


Bars 28-42: The development is founded chiefly on the first subject. It starts in the key of C major, and, passing through D minor and G minor, ends on the dominant seventh of F major (Bar 41), followed by a link which leads into the recapitulation of the first subject.


Bars 43-46: First Subject in Tonic (incomplete). There is only a partial reappearance of the first subject.

Bars 46-50: Bridge-passage (new). In all but the last bar this short passage is quite distinct from the original transition. It starts by repeating the last figure of the fragment of the first subject; and its second and third bars are derived from the last bars of the second subject.

Bars 51-68: Second Subject in tonic (slightly lengthened). 

Bars 68-74: Coda. The Coda consists of the repetition of the original transition, modified slightly, in Bar 71, to lead to the reappearance of the codetta, now, of course, in the key of the tonic.

Third Movement (Allegro)

Form: Sonata Form. C Major. 

Mozart Piano Sonata No.1 in C major, K.279 Analysis 3

The generally contrapuntal character of this movement should be noted.


Bars 1-10: First Subject in Tonic. The first subject is a sentence of ten bars and consists of two phrases. The first phrase ends Bar 4, the second, commencing an octave lower, with a repetition of the opening bars, is lengthened to six bars.

Bars 10-22: Bridge-passage or transition. The transition modulates to G major (the key of the dominant), Bar 14, in which it ends on a half-cadence, Bar 22.

Bars 22-56: Second Subject in G major (Dominant). It is interesting to note that the opening motive of the second subject is also founded on the skip of a perfect fourth; compare with the opening of the first subject. The first section (Bars 22-38), sixteen bars in length, commences with a descending sequence formed by the opening two bars being twice imitated – each time at the interval of a third below the previous entry. Bars 34-36 also form a descending tonal sequence. The second section (Bars 38-56) consists almost entirely of modified repetitions of its first two bars, 38-40. In Bars 44-46 the semiquaver (sixteenth note) movement is transferred to the treble and the melody is formed by the first and fourth notes of each group – and in Bars 48-49 and 52-53 by the second and fourth notes.

Double bar and repeat.


Bars 56-86: The development commences with a repetition of the sequence of six bars – with a slightly modified accompaniment – from the opening of the second subject. It incidentally touches the keys of D major and B minor, and passes through C major to A minor, in which key and overlapping (Bar 62) the sequence is repeated, with inversion of the parts; the repetition also touches the key of C major. Bars 72-76 form a short passage on the dominant E, approaching through the chord of the German sixth, Bar 69 (repeated Bar 71). The remainder of this section is worked on the opening motive of the first subject taken alternately in the treble and bass, and passes from the key of E minor through D minor to C major (the tonic). The section actually ends with the opening figure of the first subject in the key of the tonic, which figure is immediately repeated an octave higher in the next two bars as the commencement of the recapitulation.


Bars 86-96: First Subject in Tonic. Note that in Bars 79-80 and 83-84, in which the motive is transferred to the bass both the figure and the accompaniment are varied; and that Bars 81-84 (one note excepted) form a real sequence to Bars 77-80. In Bars 91-93 the parts are inverted, otherwise the first subject reappears practically unaltered.

Bars 96-108: Bridge-passage or Transition. The transition starts in F major and modulates to C major, corresponding to the keys of the original passage, which starts in C major and modulates to G major.

Bars 108-158: Second Subject in Tonic (lengthened). The first section spans Bars 108-124. The second section (Bars 124-158) of the second subject reappears transposed into the key of the tonic and considerably lengthened by the interpolation midway (Bars 132-147) of a portion of the first section. In Bars 135, a variation of the sequence, with which the second subject opens, commencing, but reduced from six bars to four. Following immediately and overlapping (Bar 139) there is a repetition of the same sequence in full, with the parts inverted, and the bass reinforced by octaves (compare also with Bars 62-68); the interpolated passage ends with a full cadence in the tonic, Bar 147. There is no Coda, but two extra chords are added at the close of the movement to emphasize the final cadence.