1 Otto Erich Deutsch, Mozart: Die Dokumente seines Lebens (Kassel, Basle, etc., 1961; hereafter Deutsch, Dokumente), 150; translation adapted from Deutsch, Mozart: A Documentary Biography, trans. Eric Blom, Peter Branscombe and Jeremy Noble (London, 1965; repr. 1990; hereafter Deutsch, Biography), 168. ‘Die Composition gründlich, feurig, mannigfaltig und einfach: die Harmonie so voll, so kräftig, so unerwartet, so erhebend; die Melodie so angenehm, so tändelnd, und alles so neu; der Vortrag auf dem Forte-Piano so nett, so rein, so voll Ausdruck, und doch zugleich so außerordentlich geschwinde, daß man kaum wußte, worauf man zuerst merken sollte, und alle Zuhörer zum Entzücken hingerissen wurden. Man sah hier Meisterstücke in der Gedanken, Meisterstücke in dem Vortrag, Meisterstücke in den Instrumenten, alles zusammen vereinigt. Eins erhob immer das andere so sehr, dass die zahlreiche Versammlung über nichts mißvergnügt war, als daß nicht ihr Vergnügen noch länger dauerte. Patriotisch Denkende hatten das besondere Vergnügen, aus der Stille und dem allgemeinen Beyfall der Zuhörer zu sehen, daß man bey uns wahre Schönheiten zu schätzen wisse – einen Virtuosen zu hören, der sich an die Seite der großen Meister unsrer Nation stellen darf, und doch wenigstens halb unser ist – und Instrumenten zu hören, die nach dem Urtheile der Fremden, alle andre diese Art, bey weitem übertreffen.’

2 Franz Niemetschek, Leben des k. k. Kapellmeisters Wolfgang Gottlieb Mozart (1798), ed. Ernst Rychnovsky (Munich, 1987), 27 (my translation). ‘Er ließ sich dann auf allgemeines Verlangen in einer großen musikalischen Akademie im Operntheater auf dem Pianoforte hören. Nie sah man noch das Theater so voll Menschen, als bey dieser Gelegenheit; nie ein stärkeres, einstimmiges Entzücken, als sein göttliches Spiel erweckte. Wir wußten in der That nicht, was wir mehr bewundern sollten, ob die außerordentliche Komposition, oder das außerordentliche Spiel; beydes zusammen bewirkte einen Totaleindruck auf unsere Seelen, welcher einer süßen Bezauberung glich!’ For a different (considerably looser) translation see Life of Mozart, trans. Helen Mautner (London, 1956), 36.

3 Niemetschek, Leben, 22 (my translation). ‘Eine bewundernswürdige Geschwindigkeit, die man besonders in Rücksicht der linken Hand oder des Basses einzig nennen konnte, Feinheit und Delikatesse, der schönste, redendeste Ausdruck und ein Gefühl, dessen nur ein Mozart fähig war, sind die Vorzüge seines Spieles gewesen, die gepaart mit seiner Gedankenfülle, mit der Kenntniß der Komposition natürlich jeden Hörer hinreißen, und Mozarten zu dem größten Klavierspieler seiner Zeit erheben mußten.’

4 Wolfgang Amadeus Mozart, Briefe und Aufzeichnungen: Gesamtausgabe, ed. Wilhelm A. Bauer, Otto Erich Deutsch and Joseph Eibl, 7 vols. (Kassel, Basle, etc., 1963; hereafter Mozart, Briefe und Aufzeichnungen), iii, 372–4 (p. 373; my translation). ‘Ich war hinten nur 2 Logen von der recht schönen würtemb: Princessin neben ihr entfernt und hatte das Vergnügen, alle Abwechslung der Instrumente so vortrefflich zu hören, daß mir vor Vergnügen die Thränen in den Augen standen. Als Dein Bruder weg gieng, machte ihm der Kayser mit dem Hut in der Hand ein Compli: hinab und schrie “Bravo Mozart!” – Als er herauskam zum spielen, wurde ihm ohnehin zugeklatscht.’ See also (in a different translation) The Letters of Mozart and his Family, ed. and trans. Emily Anderson (3rd edn, London, 1985; hereafter Mozart, Letters), 885–7 (p. 886).

6 Niemetschek, Leben, 27 (my translation). ‘Aber dieser Zustand lösete sich dann, als Mozart zu Ende der Akademie allein auf dem Pianoforte mehr als eine halbe Stunde phantasirte und unser Entzücken auf den höchsten Grad gespannt hatte, in laute überströmende Beyfallsäußerung auf. Und in der That übertraf dieses Phantasiren alles, was man sich vom Klavierspiele vorstellen konnte, da der höchste Grad der Kompositionskunst, mit der vollkommensten Fertigkeit im Spiele vereinigt ward.’

5 Deutsch, Dokumente, 46, 48, 53, 54–5, 58; Biography, 47, 49, 55, 56, 61–2.

7 Deutsch, Dokumente, 206 (‘seine Fantasien, welch ein Reichtum von Ideen! welche Mannigfaltigkeit! welche Abwechslung von leidenschaftlichen Tönen. Man schwimmt unwiderstehlich auf dem Strom seiner Empfindungen mit fort’), 285 (‘Diese kleine Mann und grosse Meister phantasierte zweimal auf einem Pedal-Flügel, so wundervoll! so wundervoll! dass ich nicht wusste, wo ich war. Die schwierigsten Passagen und die lieblichsten Themen ineinander verwoben’), 440 (‘Wolfgang war Auktor und Produktor zugleich, extemporierte mit unerschöpflichen Einfällen’), 480 (‘Der kühnen Flug seiner Fantasie bis zu den höchsten Regionen und wieder in die Tiefen des Abgrundes konnte auch der erfahrenste Meister in der Musik nicht genug bewundern und anstaunen. Noch jetzt, ein Greis, höre ich diese himmlischen unvergesslichen Harmonien in mir ertönen’); translations (with minor modifications) from Deutsch, Biography, 233, 325, 512, 566. Maximilian Stadler (pre-1830) also claims that ‘in the art of free improvisation Mozart had not his equal. His improvisations were as well ordered as if he had had them lying in front of him.’ See Deutsch, Dokumente, 465 (‘Mozart hatte in der freyen Fantasie Kunst Keinen seines gleichen. Er fantasierte so ordentlich, als wenn er es geschriben vor sich lieben gehabt hätte’); translation adapted from Deutsch, Biography, 543. Karl Ditters von Dittersdorf, too, records Mozart's skills as an improviser – contrasting them with the lesser skills of his imitators – and universal admiration for Mozart's playing among musicians in general. See Karl Ditters von Dittersdorf, Lebensbeschreibung: Seinem Sohne in der Feder diktirt, ed. Carl Spazier (Leipzig, 1801), trans. Arthur Duke Coleridge as The Autobiography of Karl von Dittersdorf (London, 1896), 44–5, 251. (In an interview with the emperor, relayed in the autobiography, Dittersdorf acknowledges having heard Mozart play three times by 1786–7; see Niemetschek, Leben, 27 (my translation). ‘Aber dieser Zustand lösete sich dann, als Mozart zu Ende der Akademie allein auf dem Pianoforte mehr als eine halbe Stunde phantasirte und unser Entzücken auf den höchsten Grad gespannt hatte, in laute überströmende Beyfallsäußerung auf. Und in der That übertraf dieses Phantasiren alles, was man sich vom Klavierspiele vorstellen konnte, da der höchste Grad der Kompositionskunst, mit der vollkommensten Fertigkeit im Spiele vereinigt ward.’, 251.) For Daines Barrington's famous account of Mozart improvising as a young child in London, see Deutsch, Dokumente, 89; Biography, 98.

12 Niemetschek, Leben, 57 (my translation): ‘Sein Gehör war so fein, faßte die Verschiedenheit der Töne so gewiß und richtig auf, daß er den geringsten Fehler oder Mißton selbst bey dem stärksten Orchester bemerkte, und dasjenige Subjekt oder Instrument, welches ihn begieng genau anzugeben wußte. Nichts brachte ihn so sehr auf, als Unruhe, Getöse oder Geschwätz bey der Musik. […] Alles was er vortrug, empfand er selbst auf das stärkste – sein ganzes Wesen war dann Gefühl und Aufmerksamkeit.’ See also Life of Mozart, trans. Mautner, 65.

8 Mozart, Briefe und Aufzeichnungen, ii, 343–7 (p. 344); translation (amended) from Mozart, Letters, 530–3 (pp. 531–2). ‘Geben sie mir das beste Clavier von Europa, und aber leüt zu zuhörer die nichts verstehen, oder die nichts verstehen wollen, und die mit mir nicht Empfinden was ich spielle, so werde ich alle freude verlieren.’

9 Mozart, Letters, 362–3 (p. 363), 530–3 (p. 532), 721–2 (p. 722).

10 Mozart, Briefe und Aufzeichnungen, ii, 422–8 (p. 427; letter of 31 July 1778): ‘sie wissen daß ich so zu sagen in der Musique stecke – daß ich den ganzen Tag damit umgehe’. See also (in a different translation) Mozart, Letters, 583–8 (p. 587).

11 Deutsch, Dokumente, 404; translation (slightly amended) from Deutsch, Biography, 462. ‘So lange die Musick dauert war er ganz Musick’; ‘er bemerkte bey der Vollständigsten Musick den kleinsten Missthon’; ‘Über das kleinste Geräusch bey einer Musick wurde er aufgebracht.’

13 Niemetschek, Leben, 58. ‘Als begeisterter Künstler vergaß er da auf alle andere Rücksichten’ (Life of Mozart, trans. Mautner, 65). For an early manifestation of a closely related biographical trope – Mozart escaping worldly worries through his music – in Friedrich Rochlitz's tainted anecdotes on Mozart's life, see Maynard Solomon, ‘The Rochlitz Anecdotes: Issues of Authenticity in Early Mozart Biography’, Mozart Studies, ed. Cliff Eisen (Oxford, 1991), 1–59 (p. 40). As Solomon explains, many of Rochlitz's anecdotes are ‘patently […] reworkings of Niemetschek or […] take Niemetschek's material as a point of departure for more or less imaginative elaboration’ (p. 48).

17 Mozart, Briefe und Aufzeichnungen, iii, 198–200 (p. 199); translation (amended) from Mozart, Letters, 797–9 (p. 798): ‘zugleich überschicke ich ihnen auch das lezte – welches ich zu dem Concert ex D gemacht habe, und welches hier so grossen lärm macht. – Dabey bitte ich sie aber es wie ein kleinod zu verwahren – und es keinen Menschen – auch dem Marchand und seiner schwester nicht zu spielen zu geben. – ich habe es besonders für mich gemacht – und kein Mensch als meine liebe schwester darf es mir nachspiellen.’

18 Mozart, Briefe und Aufzeichnungen, iii, 303–4 (p. 303); translation from Mozart, Letters, 869–70 (p. 869; letter of 3 March 1784): ‘nun können sie sich leicht vorstellen, daß ich nothwendig Neue Sachen spiellen muß – da muß man also schreiben. […] Nun muß ich ihnen geschwind sagen, wie es hergieng daß ich so in einen augenblik Privat accademien gebe. – der claviermeister Richter giebt im benannten Saal die 6 Sammstäge Concerte. – die Noblesse souscribirte sich daß sie keine lust hätten wenn ich nicht darin spiellte. H: Richter bat mich darum – ich versprach ihm 3mal zu spiellen. – und machte 3 Concerten für mich souscription, wozu sich alles abonnirte.’

14 Improvisation of course played a role in Mozart's concerto performances – in Eingänge, cadenzas and embellishments. Mozart commented famously to his father (22 January 1783) that for the Eingänge for the Rondo K.382 he would perform ‘whatever occurs to me at the moment’; see Mozart, Letters, 837–8 (p. 837). The extent to which Mozart's improvisations in the piano concertos were spontaneous or pre-planned is much debated. For differing viewpoints see Eva and Paul Badura-Skoda, Interpreting Mozart on the Keyboard, trans. Leo Black (London, 1962); Eva Badura-Skoda, ‘On Improvised Embellishments and Cadenzas in Mozart's Piano Concertos’, Mozart's Piano Concertos: Text, Context, Interpretation, ed. Neal Zaslaw (Ann Arbor, MI, 1996), 365–71 (p. 367); Robert D. Levin, ‘Instrumental Ornamentation, Improvisation and Cadenzas’, Performance Practice After 1600, ed. Howard Mayer Brown and Stanley Sadie (London, 1990), 267–91; Frederick Neumann, Ornamentation and Improvisation in Mozart (Princeton, NJ, 1986), esp. pp. 240–56 (Chapter 16: ‘The Special Case of the Piano Concertos’). See also Richard Taruskin, ‘A Mozart Wholly Ours’, Text and Act: Essays on Music and Performance (New York, 1995), 273–91.

15 See Simon P. Keefe, ‘“Greatest Effects with the Least Effort”: Strategies of Wind Writing in Mozart's Viennese Piano Concertos’, Mozart Studies, ed. Keefe (Cambridge, 2006), 25–46; and idem, ‘The Aesthetics of Wind Writing in the “Paris” Symphony, K.297’, Mozart-Jahrbuch 2006 (Kassel, Basle, etc., 2008), 329–44.

16 The fact that the orchestra remained outside Mozart's physical control – in contrast to the keyboard at which he performed himself – provided a source of frustration in one symphonic context at least, namely at the première of the ‘Paris’ Symphony, K.297, in 1778. Mozart wrote to his father: ‘I decided next morning not to go to the concert at all; but in the evening, the weather being fine, I at last made up my mind to go, determined that if my symphony went as badly as it did at the rehearsal, I would certainly make my way into the orchestra, snatch the fiddle out of the hands of Lahoussaye, the first violin, and conduct myself!’ See Mozart, Letters, 556–9 (pp. 557–8; letter of 3 July 1778).

19 Mozart, Briefe und Aufzeichnungen, iii, 301–2 (p. 301); iv, 40–2 (pp. 40–1); translation from Mozart, Letters, 867–9 (p. 867; letter of 20 February 1784) and 906–8 (p. 907; letter of 4 April 1787). ‘Jedes Ritornell dauert eine Viertelstunde – dann erscheint der Held – hebt einen bleyernen Fuß nach dem andern auf – und Plumpsst dann wechselweise damit zur Erde.’

20 See Ulrich Konrad, Mozarts Schaffenweise: Studien zu den Werkautographen, Skizzen und Entwürfen (Göttingen, 1992), 68–74. Mozart's distinction between ‘composing’ a piece (in draft score) and ‘writing it down’ (in complete form) should not be taken to imply that orchestration, which mostly occurs in the ‘writing down’ phase, is simply a mechanical act on his part. Rather, this distinction indicates that the act of ‘composing’ the draft score cements the details of the complete work in Mozart's mind.

21 Mozart's desire to promote himself as a performer-composer might also lie behind K.413 in F, K.414 in A and K.415 in C (1782–3), although I shall limit my investigation to his Viennese concertos from K.449 onwards. Mozart's attempt to sell manuscript copies of K.413–15 by subscription could have provided him with an additional motivation for writing these works. For accounts of this largely unsuccessful venture, see Ruth Halliwell, The Mozart Family: Four Lives in a Social Context (Oxford, 1998), 395–6, and Dorothea Link, ‘Mozart in Vienna’, The Cambridge Companion to Mozart, ed. Simon P. Keefe (Cambridge, 2003), 22–34 (pp. 31–2).

22 On authentic copies for the Salzburg and Viennese piano concertos – those prepared in consultation with Mozart and probably used by him for performance purposes – see Christoph Wolff, ‘The Many Faces of Authenticity: Problems of a Critical Edition of Mozart's Piano Concertos’, Mozart's Piano Concertos, ed. Zaslaw, 19–28, and Cliff Eisen, ‘The Scoring of the Orchestral Bass Part in Mozart's Salzburg Keyboard Concertos: The Evidence of the Authentic Copies’, Mozart's desire to promote himself as a performer-composer might also lie behind K.413 in F, K.414 in A and K.415 in C (1782–3), although I shall limit my investigation to his Viennese concertos from K.449 onwards. Mozart's attempt to sell manuscript copies of K.413–15 by subscription could have provided him with an additional motivation for writing these works. For accounts of this largely unsuccessful venture, see Ruth Halliwell, The Mozart Family: Four Lives in a Social Context (Oxford, 1998), 395–6, and Dorothea Link, ‘Mozart in Vienna’, The Cambridge Companion to Mozart, ed. Simon P. Keefe (Cambridge, 2003), 411–25. For a summary of the different types of Mozart manuscript – the autographs, draft scores, sketches – as well as styles of writing, ink colours in the manuscripts and the correction of errors, see Konrad, Mozarts Schaffenweise, 341–66.

23 Two of Mozart's Viennese piano concertos were written for his virtuoso student Barbara Ployer (K.449, 453) and one in all likelihood for another leading Viennese pianist, Maria Theresia von Paradies (K.456). All three were performed by Mozart very soon after he had entered their completion dates (9 February, 12 April, 30 September 1784) into his thematic catalogue, the Verzeichnüß aller meiner Werke; their status as works for Mozart the performer-composer, then, is no different from that of his other Viennese piano concertos from K.449 onwards. On the protracted genesis of K.449, begun in 1782–3 and left as a fragment (a particella up to bar 170 of the first movement), see Alan Tyson, Mozart: Studies of the Autograph Scores (Cambridge, MA, 1987), 19. For a stylistic reading of K.449 taking Tyson's findings as a point of departure, see Simon P. Keefe, Mozart's Viennese Instrumental Music: A Study of Stylistic Re-invention (Woodbridge and Rochester, NY, 2007), Chapter 1 (pp. 19–42).

24 For a recent account of alterations to the autograph score of Così fan tutte, with dramatic and musical issues at stake, see Ian Woodfield, Mozart's Così fan tutte: A Compositional History (Woodbridge and Rochester, NY, 2008). On changes made to accommodate individual operatic singers with particular reference to Così see also idem, ‘Mozart's Compositional Methods: Writing for his Singers’, The Cambridge Companion to Mozart, ed. Keefe, 35–47.

25 The change to the horn part in bar 14 of K.453/iii, for example, is probably harmonically motivated. Mozart originally gives a full semibreve in octaves, continuing the tied semibreves of bars 12–13. The revision replaces the semibreve with one crotchet and three crotchets’ rest, and probably accounts for the fact that the continuation of the horn d′/d would not have fitted the harmony on beat 3. (The same applies to the horn part in the second half of Variation 3, bar 86.) In K.482/ii, Mozart initially forgot bar 121, adding it in by manually extending by a few centimetres the staves on the left-hand side of the manuscript paper. At the beginning of the Andante cantabile section of K.482/iii the first two bars in the flute are crossed out, but were never intended for the flute as they are notated at transposed clarinet pitch. In the recapitulation of K.537/i Mozart crosses out 14 bars between bars 305 and 306 apparently to accommodate structural compression, jumping directly from the reprise of bar 94 in the solo exposition to the reprise of bar 122. On ‘types of errors’ (‘Fehlertypen’) in general in Mozart's autographs, see Konrad, Mozarts Schaffenweise, 356–66.

26 On the virtù of concerto virtuosity – in which expressiveness plays an important role – see Joseph Kerman, Concerto Conversations (Cambridge, MA, 1999), 61–82, and Cliff Eisen, ‘The Rise (and Fall) of the Concerto Virtuoso in the Late Eighteenth and Nineteenth Centuries’, The Cambridge Companion to the Concerto, ed. Simon P. Keefe (Cambridge, 2005), 177–91. See also Elisabeth Le Guin, Boccherini's Body: An Essay in Carnal Musicology (Berkeley, CA, 2006), Chapter 4, ‘Virtuosity, Virtuality, Virtue’ (pp. 105–59).

27 This is not to suggest that technical brilliance is in any way inexpressive – as implicitly or explicitly late eighteenth-century writers do when deriding concertos for overly ostentatious displays of brilliance – but rather to recognize simply that figurative passagework and thematic–melodic presentation on the soloist's part are demonstrably different in virtuosic effect.

28 The autograph score of the C minor Concerto, K.491, is an example of a more ‘disorderly’ manuscript, at least where the notation of the solo part is concerned. For a consideration of this autograph and the textual problems arising from it, see Robert D. Levin, ‘The Devil's in the Details: Neglected Aspects of Mozart's Piano Concertos’, Mozart's Piano Concertos, ed. Zaslaw, 29–50, esp. pp. 35–50. (He refers to it on p. 44 as ‘one of the most disorderly in the oeuvre’.) As Levin explains, ‘the solo staves were at first sketched in a hurried and barely legible script, often limited to schematic outlines’ (p. 44); on occasion (as in the second variation in the finale) revisions are so extensive that ‘no final form can be said to exist’ (p. 40). Furthermore, ‘the exact reading of certain scale passages in the last movement of K.491 [in Mozart's shorthand] cannot be surmised’ (p. 42). Ulrich Konrad attempts to decipher layers of revision to the piano part in Variation 2 of K.491/iii (bars 40–8 and 56–64), giving a facsimile and his own transcriptions, in Mozarts Schaffenweise, pp. 485–7.

29 We witness the particella compositional layer especially in Mozart's piano concertos that remained incomplete fragments for a period of time (including K.449, 488, 503; see Tyson, Mozart) and where different ink colours underscore the temporal separation of the particella from the completed composition. See, for example, the recent high-quality facsimile of K.488, where oboe parts written in the opening ritornello of the first movement during the first phase of composition in 1784 are discernibly different in ink colour from the clarinet parts finally conceived in 1786 and written on the same staves; Wolfgang Amadeus Mozart, Klavierkonzert A-dur KV488: Faksimile nach dem Autograph MS. 226 im Besitz der Musikabteilung der Bibliothèque Nationale de France, Paris (Munich, 2006). For further discussion of Mozart's compositional methods, see Konrad, Mozarts Schaffenweise; and for a succinct summary, idem (trans. Ruth Halliwell), ‘Compositional Method’, The Cambridge Mozart Encyclopedia, ed. Cliff Eisen and Simon P. Keefe (Cambridge, 2006), 100–8. Most recently, in a concerto context, see Robert D. Levin, ‘Mozart's Working Methods in the Keyboard Concertos’, The Century of Bach and Mozart: Perspectives on Historiography, Composition, Theory and Performance in Honor of Christoph Wolff, ed. Sean Gallagher and Thomas Forrest Kelly, Isham Library Papers, 7 (Cambridge, MA, 2008), 379–406.

30 It is very difficult to determine when exactly Mozart carried out these changes, and most of the other changes discussed below. It would seem reasonable to assume variability in practice – some changes made immediately, some after further material had been written, and some after a performance.

31 Unusually, in bars 156–7, it is the later version that Mozart rejects and the original that he retains. As is common for solo-part revisions in the autograph scores, Mozart writes the second version in the two staves above the piano (reserved for the two horns and two bassoons in this movement), but crosses out the revised version in favour of the original.

32 Mozart, Letters, 383–5 (p. 384; letter of 22 November 1777), 833–4 (p. 833; letter of 28 December 1782). On the applicability of Mozart's remark on K.413–15 to the remainder of his Viennese piano concertos, see Simon P. Keefe, ‘The Concertos in Aesthetic and Stylistic Context’, The Cambridge Companion to Mozart, ed. Keefe, 78–91.

33 All musical examples in this article are compiled from Mozart's autograph scores. While they preserve the original layout of Mozart's autographs – violins and viola at the top, piano and bassi parts at the bottom and wind instruments in between – they adopt modern presentational and notational conventions in other respects, omit blank staves (where indicated) and on occasion bring first and second parts for the same wind instrument together on the same stave where Mozart included them on separate staves.

34 See Ernst-Günther Heinemann, ‘Einleitung/Introduction’, Mozart, Klavierkonzert A-dur KV488, xi, xv.

35 For a brief discussion of these changes, intended to ‘challenge a philological creed that has governed musicology since its outset [… that] the object of the scholar is to approach a musical work of art as part of a definitive legacy and establish a text that reflects the composer's ultimate, final version’, see Levin, ‘Mozart's Working Methods’, 403–5.

36 Mozart's original version of bars 188–203 appears in two pages inserted into Nannerl's Salzburg copy of K.449, annotated by Nannerl as ‘extra manieren in das erste Allegro’. See Neue Mozart-Ausgabe, Kritischer Bericht, V/15/4, ed. Marius Flothuis (Kassel, Basle, etc., 1991), 7.

37 See Keefe, Mozart's Viennese Instrumental Music, Chapter 1 (pp. 19–42).

38 The crossed-out bar for horn cannot be a simple instrumentation error on Mozart's part, as it is notated at the correct transposed pitch for a horn in F – d' (sounding g) – that doubles the violas/basses and is similarly marked forte.

39 See Keefe, ‘“Greatest Effects with the Least Effort”’, 35–7.

40 Allgemeine musikalische Zeitung, 8 (1805–6), col. 729. ‘Mozart selbst dies Konzert mit mehr Ernst und imponirender Würde vortrug. Bey ihm wurde mehr der tiefe, reiche Geist der Komposition, bei Stein mehr der glänzende Vortrag des Virtuosen bemerkbar.’

41 The progression re-establishing is as follows: German augmented sixth (bar 260)–V/i^6/4 (261–3)–V (264)–I (265).

42 The sextet of instruments employed by Mozart for the wind statements in the Andante – two clarinets, two bassoons, two horns – is the exact wind combination praised highly by French aesthetician Louis Francoeur in a landmark early treatise on orchestration (Diapason général de tous les instrumens à vent avec des observations sur chacun d'eux (Paris, 1772), pp. 35, 51, 54–5) that would have been circulating in Paris during Mozart's visit in 1778. More generally, the wind statements in the Andante are informed by the Viennese tradition of Harmoniemusik. For a brief discussion of Mozart's Harmoniemusik in Vienna, Italy and Salzburg, see Roger Hellyer, ‘Wind Music’, The Cambridge Mozart Encyclopedia, ed. Eisen and Keefe, 532–6.

43 In addition, Mozart altered the upper line of the revised left-hand part of bars 106–7 (notated on the stave below) before coming up with his finalized version. Mozart's dense crossing out here makes it difficult to determine for certain what he first envisaged for the revision, although it would appear that he intended the revised syncopated rhythm either on c' and ' together or on ' only. The rejected left-hand part in bar 106 also contains a crossed-out minim (or crotchet) c', for which Mozart substitutes the semibreve c'.

44 For an article arguing a related point – ‘that a source is as representative of performance as it is representative of a “work”’ (p. 116) – see Cliff Eisen, ‘The Primacy of Performance: Text, Act and Continuo in Mozart's Keyboard Concertos’, Words About Mozart: Essays in Honour of Stanley Sadie, ed. Dorothea Link and Judith Nagley (Woodbridge and Rochester, NY, 2005), 107–19.

45 From Mozart himself – often criticizing others for lacking such qualities – see (on the importance of clear and precise keyboard playing) Mozart, Letters, 390–1 (p. 391), Briefe, ii, 145–7 (pp. 146–7; 26 November 1777), and Letters, 447–9 (pp. 448–9), Briefe, ii, 226–8 (p. 228; 17 January 1778); and (on the importance of expressive playing) Letters, 792–3 (p. 793), Briefe, iii, 191–3 (p. 192; 16 January 1782), and Letters, 875–6 (p. 875), Briefe, iii, 312 (28 April 1784). Grace and elegance are recorded by Clementi (see Leon Plantinga, Clementi: His Life and Music (London, 1977), 65), by Georg Friedrich Richter (quoted by Mozart himself in Letters, 875–6 (p. 875), Briefe, iii, 312; 28 April 1784) and by Niemetschek, as given above.

46 Levin, ‘Improvisation and Embellishment in Mozart's Piano Concertos’, Musical Newsletter, 5/2 (1975), 3–14 (p. 3). He repeats this passage in ‘Mozart's Working Methods’, 406.

47 David Grayson makes a similar remark in the context of pursuing ‘authentic’ performance: ‘We can strive for an “authentic” Mozart as long as we do not know precisely what it is but can convince ourselves that we are close to it. If we actually had an authentic Mozart on compact disc […] then we would surely lose the desire to imitate it, because our performances could then never be authentic, but would be, at best, accurate copies.’ See Grayson, ‘Whose Authenticity? Ornaments by Hummel and Cramer for Mozart's Piano Concertos’, Mozart's Piano Concertos, ed. Zaslaw, 386.

48 Another example is K.453/ii, bar 18, where the horn octave Gs in quavers are apparently a late addition. (Mozart originally gives the horns tied octave Cs in bars 19–20 and 22–3, replacing the Cs with Gs when making the addition to bar 18.)

49 Cliff Eisen argues in like-minded fashion in the context of his study of continuo performance (‘The Primacy of Performance’, 119): ‘multiplicity of function, and multiplicity of voices, suggests that texture, which can include the interplay of voices and functions all at the same time […] is as important for understanding Mozart's concertos as questions of form that have traditionally dominated the study of these works’.

50 This can be gleaned from important early critical writings whose authors seem not to have encountered Mozart as a performer. Ignaz Arnold, for example, talks little about Mozart's performance skills and a great deal about his composition-related achievements in Mozarts Geist: Seine kurze Biographie und ästhetische Darstellung seiner Werke (Erfurt, 1803). Ernst Ludwig Gerber, slightly dubious about Mozart's significance as a composer, draws attention to Mozart's status as one of the great keyboard players of his generation in Historisch-biographisches Lexicon der Tonkünstler, 2 vols. (Leipzig, 1790–2), i, cols. 977–9. But the huge, thirteenfold increase in the length of the Mozart article in Gerber's Neues historisch-biographisches Lexicon der Tonkünstler, 4 vols. (Leipzig, 1812–14) accommodates Mozart's compositional rather than performance-related achievements. On Mozart's evolving reputation in the last decade of the eighteenth century and the first of the nineteenth, witnessed through revisions to Gerber's lexicon and Niemetschek's biography, see Simon P. Keefe, ‘Across the Divide: Currents of Musical Thought in Europe, c. 1790–1810’, The Cambridge History of Eighteenth-Century Music, ed. Keefe (Cambridge, 2009), 663–87.

51 Exceptions include late eighteenth-century performers who, by virtue of their teaching or other dissemination of performance skills, intentionally or unintentionally establish a school of playing that flourishes after their death. Giovanni Battista Viotti, Pierre Rode and Pierre M. Baillot of the virtuoso French violin school are cases in point, although Viotti's compositions have recently received attention too: see Giovanni Battista Viotti: A Composer Between Two Revolutions, ed. Massimiliano Sala (Bologna, 2006).