Question: What was the main subject of biographies of the composer of Piano Sonata No. 7?

full_context: Document 1: Biographies of Mozart: Wolfgang Amadeus Mozart died after a short illness on 5 December 1791, aged 35. His reputation as a composer, already strong during his lifetime, rose rapidly in the years after his death, and he became (as he has remained to this day) one of the most celebrated of all composers.
Document 2: Piano Sonata No. 9 (Mozart): Wolfgang Amadeus Mozart's Piano Sonata No. 9 in D major, K. 311 / 284c, was written on the composer's stay in Augsburg and Mannheim in November-December 1777, and is contemporaneous with his Sonata K. 309 (Mozart wrote his Sonata K. 310 in the summer of the following year, in Paris). The three sonatas K. 309–311 were published as a set 'Opus IV' in about 1782, by Franz Joseph Heina in Paris.
Document 3: Wolfgang Amadeus Mozart: Wolfgang Amadeus Mozart (/ ˈwʊlfɡæŋ æməˈdeɪəs ˈmoʊtsɑːrt / MOHT - sart; German: (ˈvɔlfɡaŋ amaˈdeːʊs ˈmoːtsaʁt); 27 January 1756 -- 5 December 1791), baptised as Johannes Chrysostomus Wolfgangus Theophilus Mozart, was a prolific and influential composer of the Classical era.
Document 4: Symphony, K. 45b (Mozart): This work was only known to Ludwig Ritter von Köchel as an incipit in the catalogue of Breitkopf & Härtel, and thus it was placed in the Anhang as K. Anh. 214. Alfred Einstein then discovered a set of parts in the Berlin State Library with the title ""Synfonia Ex Bb...Del Sigr. cavaliere Amadeo Wolfgango Mozart Maestro di concerto di S.A. á Salisburgo"". Wolfgang became the Concertmaster to the Archbishop of Salzburg in November 1769, and was given the title "cavaliere" in July 1770, but as this is a later copy, this information cannot be used for dating purposes. Einstein believed the symphony to date from early 1768 on stylistic grounds; Neal Zaslaw and Gerhard Allroggen believe even earlier dates to also be possible, and Zaslaw dated the symphony cautiously to Salzburg in 1767. Einstein also believed that the symphonies in the catalogue of Breitkopf & Härtel were sent by Leopold Mozart to be published.
Document 5: Piano Sonata No. 8 (Mozart): Wolfgang Amadeus Mozart's Piano Sonata No. 8 in A minor, K. 310 / 300d, was written in 1778. The sonata is the first of only two Mozart piano sonatas in a minor key (the other being No. 14 in C minor, K. 457). It was composed in the summer of 1778 around the time of his mother's death, one of the most tragic times of his life.
Document 6: Piano Sonata No. 17 (Mozart): Wolfgang Amadeus Mozart's Piano Sonata No. 17 in B major, K. 570, dated February 1789, is a sonata in three movements:
Document 7: Piano Sonata No. 7 (Mozart): The work was composed during a journey to Mannheim and Paris in 1777-78. The sonata was completed in a few days in early November 1777. The andante movement is a "portrait" of his pupil Rose Cannabich, the 13-year-old daughter of the Mannheim Kapellmeister Christian Cannabich. Upon reviewing a copy of the manuscript, Mozart's father Leopold wrote that it was "a strange composition. It has something in it of the 'rather artificial' Mannheim style, but so very little that your own good style is not spoilt".
Document 8: Franz Xaver Wolfgang Mozart: Franz Xaver Wolfgang Mozart (26 July 1791 – 29 July 1844), also known as Wolfgang Amadeus Mozart, Jr., was the youngest child of six born to Wolfgang Amadeus Mozart and his wife Constanze. He was the younger of his parents' two surviving children. He was a composer, pianist, conductor, and teacher from the late classical period whose musical style was of an early Romanticism, heavily influenced by his father's mature style.
Document 9: Symphony No. 41 (Mozart): Wolfgang Amadeus Mozart completed his Symphony No. 41 in C major, K. 551, on 10 August 1788. The longest and last symphony that he composed, it is regarded by many critics as among the greatest symphonies in classical music.
Document 10: Piece in F for Keyboard, K. 33B (Mozart): Mozart wrote this piece in pencil on the back of a circular by the Zürcher Musikkollegium (Zürich Music College) dated 30 September 1766, when the Mozart family came to the end of their Grand Tour. The circular invited sponsors, music lovers and other people who might be interested to concerts by "the young (9 years old) Master Mozart as well as his maiden sister" (Maria Anna – Nannerl) on October 7 and 9. It can be assumed that Mozart played or improvised this lively piece in one of those concerts, the programs to which are lost. Mozart wrote it on the back of the circular probably as a souvenir for the College's board; otherwise he would have used his sister's notebook or his third book of sketches (""), which is also lost. The autograph became known very late (in 1942), and so is missing from Alfred Einstein's 3rd edition of the Köchel catalogue.
Document 11: Piano Sonata No. 1 (Mozart): Wolfgang Amadeus Mozart's Piano Sonata No. 1 in C major, K. 279 / 189d (1774), is a piano sonata in three movements. It was written down, except for the first part of the opening movement, during the visit Mozart paid to Munich for the production of "La finta giardiniera" from late 1774 to the beginning of the following March. A typical performance of the sonata takes about 14 minutes. It is the first of his 18 piano sonatas. All but two of the sonatas, No. 8 in A minor and No. 14 in C minor, are in a major key. Also, the first six sonatas seem to follow the cycle of fifths, to the flat side first (No. 1 in C major, No. 2 in F major, No. 3 in B-flat major, No. 4 in E-flat major) and then to the sharp side (No. 5 in G major, No. 6 in D major).
Document 12: Piano Sonata No. 14 (Mozart): The piano sonata was composed during the approximately 10-year period of Mozart's life as a freelance artist in Vienna after he removed himself from the patronage of the Archbishop of Salzburg in 1781. It is one of the earliest of only six sonatas composed during the Vienna years, and was probably written either as a teaching tool or for personal use. Sonatas during this time were generally written for the domestic sphere – as opposed to a symphony or concerto, they were designed to convey ideas in a small, intimate setting.
Document 13: Wolfgang Amadeus Mozart: Wolfgang Amadeus Mozart was born on 27January 1756 to Leopold Mozart (1719–1787) and Anna Maria, née Pertl (1720–1778), at 9 Getreidegasse in Salzburg. This was the capital of the Archbishopric of Salzburg, an ecclesiastic principality in what is now Austria, then part of the Holy Roman Empire. He was the youngest of seven children, five of whom died in infancy. His elder sister was Maria Anna Mozart (1751–1829), nicknamed "Nannerl". Mozart was baptised the day after his birth, at St. Rupert's Cathedral in Salzburg. The baptismal record gives his name in Latinized form, as "Joannes Chrysostomus Wolfgangus Theophilus Mozart". He generally called himself "Wolfgang Amadè Mozart" as an adult, but his name had many variants.
Document 14: Classical period (music): However, Vienna's fall as the most important musical center for orchestral composition during the late 1820s, precipitated by the deaths of Beethoven and Schubert, marked the Classical style's final eclipse -- and the end of its continuous organic development of one composer learning in close proximity to others. Franz Liszt and Frédéric Chopin visited Vienna when they were young, but they then moved on to other cities. Composers such as Carl Czerny, while deeply influenced by Beethoven, also searched for new ideas and new forms to contain the larger world of musical expression and performance in which they lived.
Document 15: Mozart's birthplace: Mozart's birthplace (German: ' or ') was the birthplace of Wolfgang Amadeus Mozart at No. 9 Getreidegasse in Salzburg, Austria. The Mozart family resided on the third floor from 1747 to 1773. Mozart himself was born here on 27 January 1756. He was the seventh child of Leopold Mozart, who was a musician of the Salzburg Royal Chamber.
ground_truth: Wolfgang Amadeus Mozart
sub_queries: Piano Sonata No. 7 >> composer Answer: Mozart
Biographies of Mozart >> main subject Answer: Wolfgang Amadeus Mozart