Mozart moved in with the Weber family, who had moved to Vienna from Mannheim. The father, Fridolin, had died, and the Webers were now taking in lodgers to make ends meet. Aloysia, who had earlier rejected Mozart's suit, was now married to the actor Joseph Lange, and Mozart's interest shifted to the third daughter, Constanze. The couple were married on 4 August 1782, eventually securing Leopold's "grudging consent".The couple had six children (although only two survived infancy)
In the course of 1782 and 1783 Mozart became intimately acquainted with the work of Johann Sebastian Bach and George Frideric Handel as a result of the influence of Gottfried van Swieten, who owned many manuscripts of the Baroque masters. Mozart's study of these scores inspired compositions in Baroque style.
In 1783, Wolfgang and Constanze visited his family in Salzburg. Leopold and Nannerl were, at best, only polite to Constanze; but the visit at least prompted the composition of one of Mozart's great liturgical pieces, the Mass in C minor. Though not completed, it was premiered in Salzburg, with Constanze singing a solo part.
Mozart met Joseph Haydn in Vienna, and the two composers became friends . When Haydn visited Vienna, they sometimes played together in an impromptu string quartet. Mozart's six quartets dedicated to Haydn date from the period 1782 to 1785 He stood in awe of Mozart, whose sister recorded that in 1781 Haydn told the visiting Leopold: "I tell you before God, and as an honest man, your son is the greatest composer known to me by person and repute, he has taste and what is more the greatest skill in composition."
From 1782 to 1785 Mozart mounted concerts with himself as soloist, presenting three or four new piano concertos in each season. Since space in the theaters was scarce, he booked unconventional venues: a large room in the Trattnerhof (an apartment building); and the ballroom of the Mehlgrube (a restaurant).The concerts were very popular, and the concertos he premiered at them are still firm fixtures in the repertoire.
With substantial returns from his concerts and elsewhere, he and Constanze adopted a rather plush lifestyle. They moved to an expensive apartment, with a yearly rent of 460 florins.Mozart also bought a fine fortepiano from Anton Walter for about 900 florins, and a billiard table for about 300.The Mozarts sent their son Karl Thomas to an expensive boarding school,and kept servants. Saving was therefore impossible, and the short period of financial success did nothing to soften the hardship the Mozarts were later to experience.
On 14 December 1784, Mozart became a Freemason, admitted to the lodge Zur Wohltätigkeit ("Beneficence"). Freemasonry played an important role in the remainder of Mozart's life: he attended many meetings, a number of his friends were Masons, and on various occasions he composed Masonic music.
In 1785, Mozart began his famous operatic collaboration with the librettist Lorenzo Da Ponte. 1786 saw the successful premiere of The Marriage of Figaro in Vienna, closely followed by the opera Don Giovanni, which premiered in October 1787 to acclaim in Prague, and also met with success in Vienna in 1788. The two are esteemed among Mozart's most important works and are mainstays of the operatic repertoire today, though at their premieres their musical complexity caused difficulty for both listeners and performers. These developments were not witnessed by the composer's father, as Leopold had died on 28 May 1787.
In December 1787 Mozart finally obtained a steady post under aristocratic patronage. Emperor Joseph II appointed him as his "chamber composer", a post that had fallen vacant the previous month on the death of Gluck. It was a part-time appointment, paying just 800 florins per year, and only required Mozart to compose dances for the annual balls at the palace Mozart complained to Constanze that the pay was "too much for what I do, too little for what I could do" However, even this modest income became important to Mozart when hard times arrived. Court records show that Joseph's aim was to keep the esteemed composer from leaving Vienna in pursuit of better prospects.
In 1787 the young Ludwig van Beethoven spent two weeks in Vienna, hoping to study with Mozart. The evidence concerning this time is conflicting, and at least three hypotheses are in play: that Mozart heard Beethoven play and praised him; that Mozart rejected Beethoven as a student; and that they never even met
Around 1786 Mozart had ceased to appear frequently in public concerts, and his income shrank. It was a difficult time for all musicians in Vienna because Austria was at war, and both the general level of prosperity and the ability of the aristocracy to support music had declined.
Mozart made long journeys hoping to improve his fortunes: to Leipzig, Dresden, and Berlin in the spring of 1789, and to Frankfurt, Mannheim, and other German cities in 1790. The trips produced only isolated success and did not relieve the family's financial distress.
Mozart's last year was, until his final illness struck, a time of great productivity He composed a great deal, including some of his most admired works and his financial situation, finally began to improve. In his later operas he employed subtle changes in instrumentation, orchestral texture, and tone color, for emotional depth and to mark dramatic shifts. Here his advances in opera and instrumental composing interacted: his increasingly sophisticated use of the orchestra in the symphonies and concertos influenced his operatic orchestration, and his developing subtlety in using the orchestra to psychological effect in his operas was in turn reflected in his later non-operatic compositions.
Mozart fell ill while in Prague for the premiere on 6 September of his opera La clemenza di Tito, written in 1791 He was able to continue his professional functions for some time, and conducted the premiere of The Magic Flute on 30 September. The illness intensified on 20 November, at which point Mozart became bedridden, suffering from swelling, pain, and vomiting. Mozart died at 1 a.m. on 5 December 1791 at the age of 35
Mozart's sparse funeral did not reflect his standing with the public as a composer: memorial services and concerts in Vienna and Prague were well attended. Indeed, in the period immediately after his death Mozart's reputation rose substantially