The year 1781 was hugely important for Mozart. After his triumph in Munich with Idomeneo, he was summoned to Vienna by his employer, the Archbishop of Salzburg, who was to spend several weeks in the Austrian capital and required some of his household musicians to attend him there. Mozart was suddenly relegated therefore from the position of an important guest composer-conductor in Bavaria to that of a mere servant (seated at meals "above the cooks but below the valets," as he reported bitterly in a letter to his father); and as his movements were continually restricted, so his frustrations and anger increased. By June 1781 he had had enough. Following a blazing row (by no means the first) with his employer, he was dismissed from court service. His ties with Salzburg, and to an extent therefore also with his controlling father, Leopold, were severed forever.

But new ties were swiftly established. Far from sinking without a trace in Vienna, as his dismayed father had predicted, Mozart gradually established himself as a vibrant presence in its aristocratic salons, and then in its theaters and concert halls. Within weeks of his Salzburg dismissal he was having meetings with Johann Gottlieb Stephanie, a playwright and librettist in charge of German opera. When it was announced in July that the Grand Duke Paul of Russia would visit Vienna, Stephanie asked Mozart to collaborate with him on an opera in his honor. This would be Die Entf‹hrung aus dem Serail‹The Abduction from the Seraglio. At the same time, as Mozart had to find somewhere to live as an independent musician (a thoroughly rare being at this time), he renewed his connection with the Weber family, whom he had met in Mannheim four years earlier. Then his heart had been broken by Aloysia Weber, a first-rate young singer who, now married to an actor, was enjoying a stellar career in Vienna. Aloysia's mother, also living in Vienna with her three other (unmarried) daughters‹Josefa, Constanze and Sophie‹took in lodgers. So Mozart moved in with them, and his life changed.

It is rarely advisable to try to draw parallels between a composer's output and his own story. Some artists do reflect their circumstances in their work, but Mozart was not one of them. In general his creative skills soared on some extra-mundane plane‹a world to which he could and would escape blissfully, even when under pressure. There are therefore countless examples in his music (the Jupiter Symphony, for instance) of the greatest exuberance actually being the product of an exceptionally desolate time. Paradoxically, the one instance we have of some kind of writer's block occurred during the composition of Idomeneo, which had been a very happy period for him. But here in Die Entf‹hrung the parallels between art and life are too striking to be irrelevant or coincidental. Wolfgang received his commission for the opera just as his heart was opening to the Weber girl who would in due course become his wife. Her name, and that of the opera's principal character, was Constanze. He wrote his opera and oversaw its preparation and rehearsal in the months in which he tried to persuade his family of the suitability of his choice of bride. Die Entf‹hrung had its premiere on July 16, 1782; and just over three weeks later, on August 4, Wolfgang and Constanze were married. His heart is in every bar of this ground-breaking score.

From the start, the portents for the success of this opera were excellent. The very story‹of love, valiant if foiled rescue, and magnanimous pardon‹was relevant to the host, for the Emperor Joseph II was passionate about the Enlightenment values of courage, reconciliation and forgiveness; and its Turkish context was also appropriate for the visit of the Grand Duke, who had effectively been sent to Vienna by his mother Catherine the Great, needing Habsburg solidarity against the Turks. For Mozart, the high profile of the event could not have been a better way to announce his arrival on the Viennese operatic scene. He enjoyed massive support from several aristocratic families, who had welcomed the brilliant renegade from Salzburg into their salons and been dazzled by his gifts and his personality. And the cast that he and Stephanie assembled for Die Entf‹hrung was quite simply the best he had ever had. Catarina Cavalieri, who sang the role of Constanze, was, together with Aloysia Weber, the foremost singer of her generation (and four years later Mozart was hilariously to exploit their friendly rivalry when he cast them as opposing divas in Der Schauspieldirektor). Her colleagues Johann Valentin Adamberger as Belmonte, Ludwig Fischer as Osmin and Therese Teyber as Blonde, were all hugely gifted and popular, as were the actor-singer Johann Ernst Dauer (Pedrillo) and the actor Dominik Joseph Jautz (Pasha Selim). For the first time for Mozart, there was not a single weak link in his cast, and, most significantly, all his performers were exactly the right ages for their roles: there was real dramatic verisimilitude in lustrous addition to vocal distinction. Mozart had largely shaped the libretto himself, with his natural instincts for characterization, pacing and structure; and his own passions were energized by his freedom from Salzburg and his infatuation with Constanze Weber. All this would lead to a giant leap for him as he created his Die Entf‹hrung aus dem Serail.

The most telling moment of autobiography in Mozart's new opera is surely Belmonte's first-act aria, "O wie ‹ngstlich, o wie feurig /Klopft mein liebefolles Herz" (How eagerly, how ardently my lovesick heart is beating). It begins in a heart-stopping way, as Belmonte breathes the name "Constanze!" and then "dich wiederzusehen, dich!" (to see you again!) over the gentlest of string chords. And, in a letter to his father describing, musician to musician, his compositional processes in the aria, his explanation of musical decisions is thoroughly eloquent of his own state of mind:

Let me now turn to Belmonte's aria in A major, "O wie ‹ngstlich, o wie feurig." Would you like to know how I have expressed it‹and even indicated his throbbing heart? By the two violins playing octaves. ... You see the trembling‹the faltering‹you see how his throbbing breast begins to swell; this I have expressed by a crescendo. You hear the whispering and the sighing ‹which I have indicated by the first violins with mutes and a flute playing in unison. ... This is the favorite aria of all those who have heard it, and it is mine also.

As he created this music, with his future wife beside him, Mozart effectively wrote a love letter to his own Constanze.

The eminent conductor and Mozart specialist Jane Glover, CBE, is author of the critically acclaimed book Mozart's Women.