The Piano Concerto No. 24 in C minor, K. 491, is a concerto composed by Wolfgang Amadeus Mozart for keyboard (usually a piano or fortepiano) and orchestra. Mozart composed the concerto in the winter of 1785–1786, finishing it on 24 March 1786, three weeks after completing his Piano Concerto No. 23 in A major. As he intended to perform the work himself, Mozart did not write out the soloist's part in full. The premiere was in early April 1786 at the Burgtheater in Vienna. Chronologically, the work is the twentieth of Mozart's 23 original piano concertos.
The work is one of only two minor-key piano concertos that Mozart composed, the other being the No. 20 in D minor. None of Mozart's other piano concertos features a larger array of instruments: the work is scored for strings, woodwinds, horns, trumpets and timpani. The first of its three movements, Allegro, is in sonata form and is longer than any opening movement of Mozart's earlier concertos. The second movement, Larghetto, in E major—the relative major of C minor—features a strikingly simple principal theme. The final movement, Allegretto, is a theme and eight variations in C minor.
The work is one of Mozart's most advanced compositions in the concerto genre. Its early admirers included Ludwig van Beethoven and Johannes Brahms. Musicologist Arthur Hutchings declared it to be, taken as a whole, Mozart's greatest piano concerto.
Background
Mozart composed the concerto in the winter of 1785–86, during his fourth season in Vienna. It was the third in a set of three concertos composed in quick succession, the others being No. 22 in E major and No. 23 in A major. Mozart finished composing the No. 24 shortly before the premiere of his comic opera The Marriage of Figaro; the two works are assigned adjacent numbers of 491 and 492 in the Köchel catalogue. Although composed at the same time, the two works contrast greatly: the opera is almost entirely in major keys while the concerto is one of Mozart's few minor-key works.
The premiere of the concerto was on either 3 or 7 April 1786 at the Burgtheater in Vienna; Mozart featured as the soloist and conducted the orchestra from the keyboard.
In 1800, Mozart's widow, Constanze, sold the original score of the work to the publisher Johann Anton André of Offenbach am Main. It passed through several private hands during the nineteenth century before Sir George Donaldson, a Scottish philanthropist, donated it to the Royal College of Music in 1894. The College still houses the manuscript today. The original score contains no tempo markings; the tempo for each movement is known only from the entries Mozart made into his catalogue. This is the largest array of instruments for which Mozart composed any of his concertos.
It is one of only two of Mozart's piano concertos that are scored for both oboes and clarinets (the other, his concerto for two pianos, has clarinets only in the revised version). The clarinet was not at the time a conventional orchestral instrument. Robert D. Levin writes: "The richness of wind sonority, due to the inclusion of oboes and clarinets, is the central timbral characteristic of [the concerto]: time and again in all three movements the winds push the strings completely to the side."
Exposition
The orchestral exposition, 99 measures long, presents two groups of thematic material, one primary and one secondary, both in the tonic of C minor. Another departure from convention is that the solo exposition does not re-state the secondary theme from the orchestral exposition. Instead, a succession of new secondary thematic material appears. Musicologist Donald Tovey considered this introduction of new material to be "utterly subversive of the doctrine that the function of the opening tutti [the orchestral exposition] was to predict what the solo had to say." and which Tovey describes as a passage of "fine, severe massiveness". Many later composers and performers, including Johannes Brahms, Ferruccio Busoni, Alfred Schnittke and Gabriel Fauré, have composed their own. Uniquely among Mozart's concertos, the score does not direct the soloist to end the cadenza with a cadential trill. The omission of the customary trill is likely to have been deliberate, with Mozart choosing to have the cadenza connect directly to the coda without one.
The conventional Mozartian coda concludes with an orchestral tutti and no written-out part for the soloist. In this movement, Mozart breaks with convention: the soloist interrupts the tutti with a virtuosic passage of sixteenth notes and accompanies the orchestra through to the final pianissimo C-minor chords.
II. Larghetto
Alfred Einstein said of the concerto's second movement that it "moves in regions of the purest and most moving tranquility, and has a transcendent simplicity of expression". Marked Larghetto, the movement is in E major and cut common time. The trumpets and timpani play no part; they return for the third movement.
The movement opens with the soloist playing the four-measure principal theme alone; it is then repeated by the orchestra.
This theme is, in the words of Michael Steinberg, one of "extreme simplicity". Donald Tovey refers to the fourth bar, extremely bare and lacking any ornamentation, as "naive", but considers that Mozart intended for it to be so. After the orchestra repeats the principal theme, there is a very simple bridge or transitional passage that Girdlestone calls "but a sketch" to be ornamented by the soloist, arguing that "to play it as printed is to betray the memory of Mozart".