Antonie was the daughter of Austrian diplomat, educational reformer, and art collector Johann Melchior Edler von Birkenstock (1738–1809) and his wife Carolina Josefa von Hay (born 1755 in Fulnek/Böhmen; died 18 May 1788 in Vienna). She had three siblings, two of whom died in infancy.
- Hugo Konrad Gottfried von Birkenstock (15 December 1778 in Vienna – 10 April 1825 in Ybbs an der Donau), k. k. Lieutenant in the Weydenfeld-Infantry
- Konstantin Viktor von Birkenstock (born and died 1782 in Frankfurt)
- Johann Eduard Valentin von Birkenstock (born and died 1784 in Frankfurt)
Her father was an Imperial advisor to Empress Maria Theresa and the reformist Emperor Joseph II. Through his wife, he was the brother-in-law of Joseph von Sonnenfels, the dedicatee of Beethoven's Piano Sonata in D-Major op. 28 (1802). Antonie von Birkenstock Brentano's mother was the sister of the Reformbischofs of Königgrätz Jan Leopold Ritter von Hay (1735–1794).
From 1782 until approximately 1784, the Birkenstock family lived in Frankfurt-am-Main, where Antonie's brothers Konstantin Viktor and Johann Eduard von Birkenstock were born and died in infancy. It is possible that Johann Melchior von Birkenstock became acquainted with the Brentano family at this time. In Vienna, the family lived in a forty-room mansion in the Landstraße suburb, located at Erdberggasse Nr. 98 (today, Erdbergstraße 19), which housed a large library and Birkenstock's sizable art collection.
Ten days before her eighth birthday, Antonie lost her mother to an epidemic and was sent to the school at the Ursuline convent in Pressburg.
In September 1797, prosperous Frankfurt merchant Franz Brentano (1765–1844), the half-brother of authors Clemens Brentano (1778–1842) and Bettina von Arnim (1785–1859), sent his half-sister, Sophie Brentano (1776–1800), and his stepmother Friederike Brentano née von Rottenhof (1771–1817) to Vienna to meet Antonie. Franz had met Antonie briefly at the end of 1796 or beginning of 1797. After a long negotiation with Antonie's father, Franz and Antonie were wed on 23 July 1798 at St. Stephen's Cathedral in Vienna. Eight days after the wedding, the pair departed Vienna for Frankfurt-am-Main. Antonie and Franz had six children:
- Mathilde (3 July 1799 in Frankfurt am Main – 5 April 1800)
- Georg Franz Melchior (13 January 1801 in Frankfurt am Main – 1 March 1853), married on 5 January 1835 to Lilla Pfeifer (1813–1868)
- Maximiliane Euphrosine Kunigunde (8 November 1802 in Frankfurt am Main – 1 September 1861 Brunnen/Schweiz), on 30 December 1825 married to Friedrich Landolin Karl von Blittersdorf (1792–1861). Beethoven composed a piano, violin and cello trio for her. "Beethoven never submitted Allegretto for Piano Trio for publication, perhaps because it was too casual in nature. He wrote it for his 10 year old piano student, Maxe Bentano, and affixed a note, “for my little friend to encourage her in piano playing. LvB.”"
- Josefa Ludovica (29 June 1804 in Frankfurt am Main – 2 February 1875), on 28 May 1832 married Anton Theodor Brentano-Tozza (1809–1895)
- Franziska Elisabeth, known as Fanny (26 June 1806 in Frankfurt am Main – 16 October 1837), in 1836 married Johann Baptist Josef Reuss
- Karl Josef (8 March 1813 in Frankfurt am Main – 18 May 1850)
In August 1809, Antonie returned to Vienna to care for her ailing father, who died on October 30, 1809. After his death, Antonie remained in Vienna for three years to sort out her father's art collection and supervise its sale. Franz Brentano established a branch of his business in Vienna and joined his wife there. Bettina von Arnim, in her epistolary novel Goethe's Correspondence with a Child describes Birkenstock's collection as follows: "I am much pleased with the old tower, from whence I overlook the whole Prater: trees on trees of majestic appearance, delightful green lawns. Here I live in the house of the deceased Birkenstock, in the midst of two thousand engravings, as many drawings, as many hundred antique urns, and Etrurian lamps, marble vases, antique remains of hands and feet, pictures, Chinese dresses, coins, collections of minerals, sea-insects, telescopes, countless maps, plans of ancient buried kingdoms and cities, skilfully carved sticks, valuable documents, and lastly the sword of the Emperor Carolus. All these surround us in gay confusion, and are just about being brought into order, so there is nothing to be touched or understood, and with the chesnut-alley in full blossom, and the rushing Danube, which bears us over on his back, there is no enduring the Gallery of Art."
Maynard Solomon's Immortal Beloved theory
American Beethoven scholar Maynard Solomon, in his 1972 article "New Light on Beethoven's Letter to an Unknown Woman" and his 1977 follow-up essay, "Antonie Brentano and Beethoven", sets forth the theory that Antonie was the composer's Immortal Beloved. Although Solomon's theory enjoyed a long vogue, it has been widely discredited by scholars such as Goldschmidt, Beahrs, Gail S Altman and Marie-Elisabeth Tellenbach. Solomon himself acknowledges that his evidence is at best circumstantial. As Beethoven enjoyed a deep friendship with Antonie Brentano's husband, it is unlikely that, given what is known about Beethoven's moral code, he could have engaged in an affair with a friend's wife. In addition, there is strong evidence that the relationship between Antonie and Franz Brentano was not as unsatisfactory as Solomon purports.
Other possible candidates for the "Immortal Beloved" include: Therese von Brunswick (1775–1861), Josephine Brunsvik (1779–1821), Countess Marie Erdődy (1779–1837), the singer Amalie Sebald, and Giulietta Guicciardi (1782–1856).
It was only recently that Solomon's Antonie hypothesis was finally and thoroughly refuted. The answer to this perennial question can be found already in the second part of Beethoven's famous Letter:
(1) "Mondays – Thursdays – the only days when the mail coach goes from here to K."
(2) "... you will probably not before Saturday receive the first message from me."
Beethoven was in Teplitz when he wrote this on Tuesday the 7th (no doubt about that), and Antonie Brentano was (as Beethoven knew very well) at the same time (for several weeks) in "K" (Karlsbad). From Teplitz to Karlsbad (ca. 100 km), the post coach took just one day. Therefore, if it had been intended for Antonie, she would have received the Letter on Friday morning, the latest. If, however, Beethoven expected the addressee to receive the Letter not before Saturday (and "probably") then she must have been two days away from Teplitz, or one more day from Karlsbad – in a westerly direction: the next bigger township is Eger [Cheb], ca. 50 km from Karlsbad (and Franzensbad another 10 km away). Now it is established that Antonie is definitely ruled out, it helps to know that the Austrian Emperor was briefly in Franzensbad on 5 July 1812, and given the known fact that Josephine's first husband was a personal friend of the Emperor (to whom she went to ask for help, after becoming a widow), it makes sense to assume that she tried to meet him there (after her encounter with Beethoven on 3–4 July).
After the Brentanos returned from Vienna, Franz was elected a senator of Frankfurt (1816). Antonie was known as "the mother of the poor" for her work in raising funds for the poor and disenfranchised citizens of Frankfurt. She founded and ran several charities. Antonie was also one of the foremost cultural figures in Frankfurt and helped to establish a salon society there. The Brentanos entertained notables such as Goethe and the brothers Grimm both at their house in Frankfurt and at their summer home, Winkel near Rheingau.
- Schenck zu Schweinsberg, Karen (1985). Meine Seele ist bey Euch Geblieben. Germany: Acta humanoria. ISBN 3-527-17537-7.
- von Arnim, Bettina (1837). Goethe's Correspondence with a Child (English Ed). London, UK: LONGMAN, ORME, BROWN, GREEN, AND LONGMANS.
- Already in 1955 the French scholars Jean and Brigitte Massin had noticed the fact that Antonie Brentano was present in Prague and Karlsbad at the time and discussed her as a possible candidate for the “Immortal Beloved”: "The assumption that it could have been Antonie Brentano, is both tantalizing and absurd." („L’hypothèse d’Antonia Brentano est à la fois séduisante et absurde.“ Jean and Brigitte Massin 1955, p. 240)
- Schenk zu Schweinsberg, Karen (1985). Meine Seele ist bey Euch Geblieben. Acta humanoria. ISBN 3-527-17537-7.
- Strohmeyer, Armin (2006). Die Frauen der Brentanos: Portäts aus drei Jahrhunderten. Berlin: Claasen.
- http://lvbeethoven.co.uk/page12.html%7CBeethoven reference site
- Solomon, Maynard (April 1977). "Antonie Brentano and Beethoven". Music and Letters 58 (2): 153–169. doi:10.1093/ml/58.2.153.
- Robinson, Henry Crabb (1898). Diary and Reminiscences of Henry Crabb Robinson. Boston: Houghton Mifflin.
- Andreas Niedermayer, Frau Schöff Johanna Antonia Brentano. Ein Lebensbild, Frankfurt 1869
- Goethes Briefwechsel mit Antonie Brentano 1814–1821, ed. Rudolf Jung, Weimar 1896
- Max Unger, Auf Spuren von Beethovens „Unsterblicher Geliebten“, Langensalza 1911
- Hermine Cloeter, Das Brentano-Haus in Wien, in: dies., Zwischen Gestern und Heute. Wanderungen durch Wien und den Wienerwald, Wien 1918, pp. 148–162
- Peter Anton von Brentano di Tremezzo, Stammreihen der Brentano mit Abriß der Familiengeschichte, Bad Reichenhall 1933
- Maria Andrea Goldmann, Antonia Brentano, die Frau Schöff, in: Goldmann, Im Schatten des Kaiserdomes. Frauenbilder, Limburg 1938, pp. 69–163
- Jean & Brigitte Massin: Ludwig van Beethoven, Paris 1955
- Maynard Solomon, New light on Beethoven's letter to an unknown woman, in: The Musical Quarterly, Vol. 58 (1972), pp. 572–587
- Maynard Solomon, "Antonie Brentano and Beethoven", in: "Music and Letters", Vol. 58, no 2 (1977): pp. 153–169.
- Harry Goldschmidt, Um die Unsterbliche Geliebte, Leipzig: Deutscher Verlag für Musik 1977
- Virginia Oakley Beahrs, "The Immortal Beloved Riddle Reconsidered." in: Musical Times, Vol. 129, No. 1740 (Feb. 1988), pp. 64–70.
- Marie-Elisabeth Tellenbach, Psychoanalysis and the Historiocritical Method: On Maynard Solomon‘s Image of Beethoven, in: The Beethoven Newsletter 8/3 (1993/1994), S. 84–92; 9/3, S. 119–127
- Klaus Martin Kopitz, Antonie Brentano in Wien (1809–1812). Neue Quellen zur Problematik „Unsterbliche Geliebte“, in: Bonner Beethoven-Studien, Band 2 (2001), S. 115–146, ISBN 3-88188-063-1, http://www.beethoven-haus-bonn.de/da_literatur/BBS2_Kopitz_AntonieBrentano.pdf
- Klaus Martin Kopitz, Antonie Brentano, in: Das Beethoven-Lexikon, ed. Heinz von Loesch and Claus Raab, Laaber 2008, pp. 144 f.