[9] In a letter of 31 March to his friend Leopold Kupelwieser, he describes the failure of his latest opera projects and voices his despair over his health situation.

[2][8][9][17][18] Around this time his friend Moritz von Schwind wrote to Kupelwieser informing him that the composer had left for Hungary, planning to write a symphony.

Freylich ists nicht mehr jene glückliche Zeit, in der uns jeder Gegenstand mit einer jugendlichen Glorie umgeben scheint, sondern jenes fatale Erkennen einer miserablen Wirklichkeit, die ich mir durch meine Phantasie (Gott sey's gedankt) so viel als möglich zu verschönern suche.

Man glaubt an dem Orte, wo man einst glücklicher war, hänge das Glück, indem es doch nur in uns selbst ist, und so erfuhr ich zwar eine unangenehme Täuschung ..., doch bin ich jetzt mehr im Stande, Glück und Ruhe in mir selbst zu finden, als damals.

Surely, these are no longer the happy days, in which everything bathes in youthful glory, but the fatal recognition of a miserable reality, which, through my fantasy (thank God) I endeavour to embellish as much as possible.

I am, praise God, still in good health, and would consider myself well off here, if I'd have you, Schober and Kupelwieser by my side: thus, however, I sense, notwithstanding a certain attracting star, often a damned homesickness for Vienna.

I composed a grand Sonata and Variations for four hands, the second having become very popular here: while I don't completely trust the taste of the Hungarians, I leave it to you and the Viennese to be the judge on that.

Ich habe seit der Zeit, dass du weg bist, beinahe keine Lieder componirt, aber mich in einigen Instrumental-Sachen versucht.

Ungeachtet ich nun seit fünf Monaten gesund bin, so ist meine Heiterkeit doch oft getrübt durch Deine und Kuppels Abwesenheit, und verlebe manchmal sehr elende Tage; ... ... Now I'm left alone here in rural Hungary, where I let myself be drawn for a second time, without having a soul with whom to engage in clever conversation.

Although I'm now healthy for five months, my joy is often dampened by your and Kupel[wieser]'s absence, and I often live miserable days; ... Schubert returned to Vienna in October, in a carriage together with Baron Karl von Schönstein [de], a friend of Count Esterházy to whom Schubert had dedicated Die schöne Müllerin and who had participated, together with the composer and members of the Esterházy family, in music performances at Zseliz.

[38][39][40] Some three decades later, after becoming a champion of Schubert's music, Schönstein wrote:[38][41][42] Welch musikalisch-schöpferischer Reichtum in Schubert lag, erkannte man bald im Hause Esterházy; er wurde ein Liebling der Familie, blieb auch über Winter in Wien Musikmeister im Hause und begleitete die Familie auch spätere Sommer hindurch auf das genannte Landgut in Ungarn.

Ein Liebesverhältnis mit einer Dienerin, welches Schubert in diesem Hause bald nach seinem Eintritt in dasselbe anknüpfte, wich in der Folge einer poetischeren Flamme, welche für die jüngere Tochter des Hauses, Komtesse Karoline, in seinem Inneren emporschlug.

Ich sage, denn er sie liebe, mußte ihr durch eine Äußerung Schuberts – die einzige Erklärung in Worten – klargeworden sein.

Als sie nämlich einst Schubert im Scherz vorgeworfen, er habe ihr noch gar kein Musikstück dediziert, erwiderte jener: "Wozu denn, es ist Ihnen ja ohnehin alles gewidmet."

A love affair with a servant, in which Schubert got himself involved shortly after entering the household, ceded, thereafter, for a more poetic flame which burst from his heart for the junger daughter of the house, Countess Karoline.

[14][43][44] In March 1828, on the anniversary of Beethoven's death, Schubert gave his only public concert: its scale was somewhat smaller than the ambition he voiced in his letter to Kupelwieser four years earlier (only chamber music was performed), but it was a considerable success.

Wer so viel schreibt wie Schubert, macht mit Titeln am Ende nicht viel Federlesens, und so überschrieb er sein Werk in der Eile vielleicht Sonate, während es als Symphonie in seinem Kopfe fertig stand; des gemeineren Grundes noch zu erwähnen, daß sich zu einer Sonate doch immer eher Herausgeber fanden, als für eine Symphonie, in einer Zeit, wo sein Name erst bekannt zu werden anfing.

So verhalten sich diese Symphonieensätze zu denen Beethoven's und können in ihrer Innigkeit gar nicht anders, als von Schubert gedacht werden.

So sehr gerade das Adagio an Beethoven erinnert, so wüßte ich auch kaum etwas, wo Schubert sich mehr gezeigt als Er; so leibhaftig, daß einem wohl bei einzelnen Tacten sein Name über die Lippen schlüpft, und dann hat's getroffen.

Auch darin werden wird übereinstimmen, daß sich das Werk vom Anfang bis zum Schluß auf gleicher Höhe hält; ... ... it seems to me that the Duo still originated under Beethoven's influence, so that I considered it a Symphony transcribed for piano, until the original manuscript, in which [Schubert] designated it as "Sonata for four hands", would instruct me otherwise.

Being acquainted with his style, his way of treating the piano, and comparing this work with his other Sonatas, from which the clearest pianistic character speaks, I can only see it as an orchestral piece.

Nonetheless I'd defend the Duo against the reproach that it wouldn't have been conceived throughout as a piano piece, that it would challenge the instrument above its possibilities, while it can be seen in a different light as an arranged symphony.

True, also [Schubert] has his forceful moments, he also can conjure up massive [sounds]; nonetheless, it always relates as woman to man, the latter commands where the former pleads and persuades.

[29] Donald Tovey wrote about the Grand Duo in 1935, mostly reiterating Schumann's views, and further contributing to the conflation of the Gmunden-Gastein Symphony with the piano four-hands Sonata.

[78] The arguments against the "symphony in disguise" proposition are summarized thus in the 1978 edition of the Deutsch catalogue:[22] Schuberts Überschift "Sonate", außerdem seine Berichte von der Komposition einer "großen Sonate ... zu 4 Hände" in Briefen aus Zseliz (...) sprechen indessen ebenso gegen ein zugrundeliegendes Orchesterwerk, wie stilistisch die zahlreichen klavieristischen Spielfiguren.

[14][105] Joachim's arrangement of the Grand Duo was, in the last decades of the 20th century, recorded by: Schubert's autograph of the Sonata ended up in the Bodleian Library, as part of the Margaret Deneke Mendelssohn collection.

[27] Pianists recording the Grand Duo in the 21st century: In his book on Schubert's Winterreise, Ian Bostridge writes that the scholarly discussions about whether the composer was homosexual died out some two decades after they began.

Giving an overview of these discussions, Bostridge describes it as anachronistic to paste late 20th-century concepts about gayness to Schubert's early 19th-century world: androgyny, the femininity alluded to by Schumann, even homo-eroticism as in some of Goethe's writings (e.g. the "Ganymed" poem which was set by Schubert, D 544), belonged to that early Romantic world, without it being possible to conclude anything sexual (as in homosexual) with regard to the composer from that cultural environment.

[14] Michael Stegemann [de], who wrote the programme notes for that concert, distances himself from the idea that Schubert would have unconsciously written for orchestra while composing the Sonata.

[14] In a contribution published in 2016, Hans-Joachim Hinrichsen analyses the part of Schubert's March 1824 letter to Kupelwieser about paving his way to the grand symphony via chamber music compositions.