For at least the past half century it has been universally said in the Mozart literature (and repeated in innumerable program and liner notes) that Mozart’s concert in Vienna on 7 Apr 1786 took place in the Burgtheater. It did not. The item from the Wiener Zeitung transcribed above is the only known evidence for the concert; in the sentence referring to it, the antecedent of “in diesem Theater” (“in this theater”) is “k. k. Hoftheater nächst dem Kärntnerthor”—namely, the Kärntnertortheater, not the Burgtheater.
The error can be traced back to Deutsch, who places the concert in the Burgtheater (Dokumente, 237). However, Deutsch transcribes only part of the item from the Wiener Zeitung (the sentence beginning “Freitag den 7. d. gab Mozart”), omitting the opening sentence that clarifies the antecedent of “in diesem Theater”. Thus when he writes in his commentary “Das Theater war das Burgtheater” (“the theater was the Burgtheater”), there is nothing in the text he transcribes to gainsay it. His error was not corrected in Addenda.
This item in the Wiener Zeitung seems first to have been cited (although not quoted) in the second edition of Otto Jahn’s Mozart biography. Jahn writes:
Für die Fasten 1786 hatte Mozart, wie er seinem Vater schrieb (28. Dec. 1785), drei Subscriptions=Akademien mit 120 Subscribenten zu Stande gebracht; für dieselben waren auch drei neue Concerte geschrieben in Es dur (482 K. N. 6) am 26. Dec. 1785, in A dur (488 K. N. 2), am 2. März 1786 und in C moll am 24. März 1786, dessen Andante er in der Akademie am 7. April, der letzten, welche im Theater gegeben wurde54, repetiren mußte.
 Wien. Ztg. 1786 Nr. 28 Anh. [Jahn 1867, i:727]
Mozart had, as he wrote to his father (28 Dec 1785), organised three subscription concerts for Lent 1786 with 120 subscribers; he wrote three new concertos for these: in E-flat major (K. 482, No. 6) on 26 Dec 1785; in A major (K. 488, No. 2) on 2 Mar 1786; and in C minor on 24 Mar 1786, the Andante of which he had to repeat in his academy on 7 Apr, the last given in the theater.54
 Wiener Zeitung 1786, No. 28, Anhang.
Jahn does not transcribe the item from the Wiener Zeitung, nor does he specify the theater. His sentence remains essentially unchanged in subsequent editions of the biography, and all retain the agnostic “im Theater.” Even Hermann Abert, who slightly rewrites the passage, does not specify the theater more precisely:
Das Andante des Cmollkonzerts mußte er in der Akademie am 7. April, der letzten, die im Theater stattfand5, wiederholen.
 Wiener Zeitung 1786, Nr. 28 Anh. [Abert 1919, i:1015]
He had to repeat the Andante of the C-minor concerto at his concert on 7 Apr, the last one that took place in the theater.5
 Wiener Zeitung 1786, No. 28, Anhang
Eisen and Spencer, in their English edition of Abert, on the other hand, specify the location as the Burgtheater, adding a citation to Dokumente, evidently their source (Abert 2007, 714).
The andante of the C minor concerto was encored at his concert on 7 April, the last of his concerts to be held at the Burgtheater.138
 Supplement to the Wiener Zeitung (8 April 1786), no. 28 (Dokumente, 237, Documentary Biography, 271).
It seems that only Deutsch actually consulted the original item in the Wiener Zeitung. Unfortunately he used it carelessly, and no one double-checked.
In our entry on the production of Mozart’s Idomeneo at Prince Auersperg’s, we describe an important change to the programming policy of the Viennese court theaters in 1786: for the first time, staged theatrical performances were allowed during Lent. The new policy was explained in detail in a notice published in the Wiener Zeitung on 8 Mar 1786, six days after it had been put into effect:
Da während dieser Fastenzeit von dem k. k.
Nationalhofschauspielern fünf Wochen lang
allemal Sonntags, Montags, Diensttags und
Donnerstags im k. k. Hoftheater beym Kärnt=
nerthor Schauspiele gegeben werden sollen, so
wurde Donnerstag den 2. März der Anfang
den übrigen Tagen in jeder Woche werden in
demselben Theater musikalische Akademien ge=
geben: die erste war zum Vortheil der Sig.
Coltellini, und die zweyte für Herrn Calvesi,
beyde Mitglieder von dem k. k. italiänischen
[WZ, no. 19, Wed, 8 Mar, Anhang, 510]
Because during this Lenten season plays
are to be given in the court theater next to
the Kärntnertor for five weeks on Sundays,
Mondays, Tuesdays, and Thursdays, this
began on Thursday, 2 March [...]
On the other days in each week musical
academies will be given in the same theater:
the first was for the benefit of Signora Coltellini,
and the second for Herr Calvesi, both members
perial royal Italian opera.
(For the full text of this notice, see the discussion in our entry on Auersperg’s Idomeneo.)
Hadamowsky’s calendar for the court theaters shows that this is exactly what happened. Ash Wednesday (the beginning of Lent) fell on 1 Mar in 1786, and Easter on 16 Apr. Plays were given in the Kärntnertortheater on Sun, Mon, Tue, and Thu for the first five weeks of Lent, ending with the double bill of Schröder’s Der Vetter in Lissabon and Der Heurath durch ein Wochenblatt on Thu, 6 Apr 1786, just as reported in the Wiener Zeitung on 8 Apr. We are relatively poorly informed about individual benefit concerts in the court theaters in Lent 1786, but all those we know of took place in the Kärntnertortheater on the other days of the week: benefit concerts for Celeste Coltellini (Fri, 3 Mar), Vincenzo Calvesi (Sat, 4 Mar), the violinist Giornovichi (Wed, 22 Mar), and Mozart (Fri, 7 Apr); and an otherwise unspecified concert in the Kärntnertortheater attended by Count Zinzendorf that included “musique d’Orfée” (Sat, 11 Mar; see Link 1998, 267). So far as we know, the Burgtheater remained closed throughout the first five weeks of Lent 1786, reopening only on Sat and Sun, 8 and 9 Apr, for the concerts of the Tonkünstler-Societät, which featured Dittersdorf’s new oratorio Giobbe (Pohl 1871, 61–62). Both court theaters remained closed during Holy Week (10–16 Apr).
We have no evidence of the program of Mozart’s concert in the Kärntnertortheater on 7 Apr. It is often said (following Jahn) that Mozart performed the Piano Concerto in C minor, K. 491, at this concert; in fact, it is often said to have been the premiere of the concerto. But this is just a guess (albeit a plausible one), based on the date under which Mozart entered the concerto into his catalog, 24 Mar 1786: it is the last entry in the catalog before the date of the concert, and the last until Le nozze di Figaro, which Mozart entered under the date 29 Apr (the opera premiered on 1 May). Yet Jahn states as fact that K. 491 was performed at the concert on 7 Apr, and adds that the “Andante” of the concerto was encored—an odd claim, given that the second movement of the concerto has the tempo designation “Larghetto” (added to the autograph by a hand other than Mozart’s; Mozart himself gave no tempo). But there is no known documentary evidence confirming that K. 491 was performed on 7 Apr, and a fortiori, no evidence that its slow movement was encored. How did Jahn’s error come about?
Very few of Mozart’s letters survive from the mid 1780s. None of his letters to his father survive between 9 Jun 1784 and 4 Apr 1787, and none to his sister between 18 Aug 1784 and 2 Jun 1787. (Only seven of his letters to anyone else survive from that period.) Everything we know of the content of Mozart’s letters to his father over that span is reported second hand in Leopold’s letters.
In a letter to his daughter dated 13 Jan 1786, Leopold reports briefly on a letter from Wolfgang dated 28 Dec 1785:
unter der Zeit hab auf 2 Brief von mir erst eine Antwort von deinem Bruder vom 28 Decemb: erhalten. Er schrieb mir das er in Eyle 3 Subscriptions Accademien gegeben von 120 Suscribenten; — daß er ein neues Clavierconcert ex Eb dazu gemacht, wo er |: das etwas seltsammes ist :| das Andante repetieren musste; [...]
In the meantime I have received just one answer from your brother, from 28 Dec, to two letters from me. He writes me that he hurriedly gave 3 subscription academies with 120 subscribers; — that he created for these a new keyboard concerto in Eb, where (this is something unusual) he had to repeat the Andante.
The concerto is K. 482, which Mozart entered into his catalog under the date 16 Dec 1785. Nothing else is known about these subscription concerts, including their dates, but Leopold’s use of the past tense (“gegeben”) in reporting a letter from Wolfgang dated 28 Dec 1785 suggests that the concerts had already happened, which in turn implies that they were Advent concerts (Advent began on Sun, 27 Nov in 1785)—not a prospective series for Lent as Jahn claims. Mozart also performed a piano concerto at the concert of the Tonkünstler-Societät on 23 Dec 1785 (Dokumente, 227–28; Pohl 1871, 61); the poster for the concert states that Mozart’s concerto was “new,” so it has reasonably been assumed that Mozart performed K. 482 at that concert as well.
Jahn evidently knew of Leopold’s letter of 13 Jan 1786 that mentions Wolfgang’s subscription concerts, although just how he knew it is unclear (it is not in Nissen 1828). In any case, Jahn muddles the content and chronology. Because Mozart’s subscription concerts took place in Advent 1785 (not Lent 1786), he cannot have written the concertos K. 488 and K. 491 for them, as Jahn claims, because Mozart entered those works into his catalog under the dates 2 Mar 1786 and 24 Mar 1786. And Jahn apparently confuses K. 491 in C minor with K. 482 in Eb major (the concerto to which Leopold refers) when he claims that the “Andante” of K. 491 was encored (it was actually the Andante of K. 482). This muddle then passed unchanged into Abert, and (oddly) is reproduced without comment in Eisen and Spencer’s English translation.
Jahn writes that the concert on 7 Apr 1786 was Mozart’s “last given in the theater” (“der letzten, welche im Theater gegeben wurde”; Jahn 1867, i:727). It is true that until recently this was Mozart’s last documented concert in either of the court theaters in Vienna (his last known concert in the Burgtheater took place on 10 Mar 1785; see Morrow 1989, 260). However, we now know that Mozart gave a benefit concert in the Kärntnertortheater on Wed, 28 Feb 1787 (see our entry for that date), currently his last known concert in either of the court theaters in Vienna.
That Mozart’s concert on 7 Apr 1786 took place in the Kärntnertortheater rather than the Burgtheater is of no special significance in itself, but it does serve as a reminder that errors made long ago in the secondary literature on Mozart have sometimes become established as “facts” through incessant repetition and a failure to revisit primary sources.