Some of the highest pinnacles in opera have been scaled by fortuitous combinations of librettist and composer. Boito and Verdi spring to mind, and Hofmannsthal with Richard Strauss. Non-purists might add Gilbert and Sullivan. But for the creation of multiple iconic masterpieces in an astonishingly short period of time, nothing matches the partnership of Wolfgang Amadeus Mozart with Lorenzo da Ponte. It yielded three works of surpassing genius within four years: Le Nozze di Figaro, Don Giovanni, and Cosí fan tutte.

Yet it is entirely possible that these treasures would never have come to pass were it not for providential coincidences of time, place and circumstance. During the last years of Mozart's life, the penultimate decade of the 18th century, events occurring in Venice, Paris, even Philadelphia, impinged upon life in Vienna, a city careening through its own social and political changes. These in turn affected the composer's fortunes and thoughts, catalyzed his collaborations with da Ponte, and even led to his final operas: that autumnal flowering of opera seria, La Clemenza di Tito, and the magnificent life-summing singspiel Die Zauberflöte.

Emperor Joseph II, exceptionally liberal by the standards of his time, assumed full power in Austria in 1780 upon the death of his mother, the stiff-necked Maria Theresa. Within six months Mozart pulled free from his despised servitude to the Archbishop of Salzburg and came to the enticing capital, confident of prosperity as a freelance performer, composer, and sometime teacher.

At first both were exceedingly popular. Mozart's concertizing was profitable, his music widely admired. Joseph instituted broad reforms of state and Church despite a wary aristocracy, and was beloved by the hoi-polloi. He even encouraged Freemasonry as an expression of enlightened thinking, disregarding the Papal Bulls condemning it. Its many adherents included Mozart.

By the late 1780s, everything had changed. The American Revolution had succeeded; Joseph's sister Marie Antoinette was facing dangerously rebellious Parisians; his own throne seemed vulnerable. Pushed by reactionary advisors, he began revoking the freedoms he had instituted. In 1785 he turned against the Masons, with escalating ferocity. By the time of his death in 1790 he had wrenched the city close to despotic tyranny.

For Mozart, five years of shifting preferences and competitor intrigues had turned the tide so unkindly that the former child prodigy, the darling of society, had become just one more musician, reduced to entreating his publisher for advances. His performances no longer sold well, and writing instrumental music generated little profit unless sponsored. Joseph's experiment with a German-language opera company, for which Mozart had happily supplied the 1782 singspiel Die Entführung aus dem Serail, had failed. Now Emperor and public both demanded opera buffa. Italy provided a profusion of suitably well-schooled and importable singers along with practiced composers like Antonio Salieri, Giovanni Paisiello, and the Italianized Spaniard Vicente Martìn y Soler. Financial exigency left Mozart no choice but to join them.

Meanwhile da Ponte had come to town, the right man at the right time. Mozart wrote to his father, "the best thing of all is when a good composer, who understands the stage and is talented enough to make sound suggestions, meets an able poet."

Da Ponte was born Jewish in the Venetian Republic, but his family had converted. The quick-witted Lorenzo attended seminary, learned Latin and Greek, took minor orders, and became a widely read author. However, he also dallied with married women and could not resist brazenly teasing the authorities with his vitriolic pen. Inevitably, he was exiled. After some wandering, he landed in Vienna in 1781. Under the still-tolerant Joseph, that city was likely the only European capital so open to him. There his services as a librettist were soon in demand. It was only after the Austrian Empire's full retreat into autocracy that da Ponte's naughtiness again led to exile. He ultimately emigrated to America, ended his varied career as an unpaid professor of Italian at Columbia University, and died impoverished.

In his memoirs, da Ponte wrote that Mozart came to him with the idea for Le Nozze di Figaro. "He asked me if I could easily arrange as an opera the comedy by Beaumarchais… The idea pleased me … but there was great difficulty to overcome…."

Indeed there was. While Beaumarchais' play Le Barbier de Séville was a farce which had already been turned into a successful opera buffa by Paisiello, its sequel, Le Marriage de Figaro, où la Folle Journée, was something different. Joseph had already forbidden any performance of the German translation because it had the smell of revolution about it. Here a servant not only prevails over his master but makes several overtly political speeches! Da Ponte had to assure the Emperor that "I have omitted and shortened anything that could offend the sensibility and decency of a spectacle at which His Sovereign Majesty presides."

Mozart's father had other concerns: jealous rivals in Vienna. He wrote to Wolfgang's sister, "I know that very powerful cabals have ranged themselves against your brother. Salieri and all his supporters will try again to move heaven and earth to down his opera… So many people are plotting against him." Salieri did not poison Mozart, Amadeus notwithstanding, but he surely poisoned the atmosphere around him.

Still, because of the electric nature of the Beaumarchais play, there was much buzz when the opera premiered on May 1, 1786. English tenor Michael Kelly, the first Don Basilio and Don Curzio, wrote, "… Never was anything more complete than the triumph of Mozart and his Nozze di Figaro."

The enthusiasm came mostly from the gallery, though; other sources spoke of discontent from the expensive seats. After only nine performances Figaro was shoved aside by another opera with a da Ponte libretto, Soler's Una Cosa Rara.

Mozart was, as stand-up comics say, too good for the room. Unlike his competitors, his innate genius had been honed by an astonishingly rich range of compositions, from chamber music to symphonies and masses. In opera, he went far beyond the simple melodies, broad jokes, and easy sentimentality of his contemporaries, beyond what the audiences expected or could absorb. He utilized Classical sonata form to accentuate dramatic situations, even incorporated counterpoint into ensembles to clarify characters' intentions and motives. For all the incredible beauties of the music, Mozart gave the people more than they wanted.

Examples abound. The Act I scene in which the Count discovers Cherubino hiding on the wing chair would have been simple horseplay in most treatments, but Mozart used the relationship of tonic and dominant keys to raise and then release tensions, adding emotional dimensions far deeper than the usual norm. Even more disquieting, by Act II he had shifted the entire center of gravity in this "crazy day" away from Figaro's wedding to the betrayal, distress, and eventual forgiveness of the Countess, a level of insightful humanity which may have disturbed good burghers out for some laughs and a few uncomplicated tunes.

Mozart's opponents reflected prevalent sentiment when they dismissed his music as too erudite. Even a usually supportive Frankfurt critic wrote that it "is for the connoisseur who knows how to unravel its refinements."

However, when Le Nozze di Figaro was produced that December in Prague, a provincial city with lower political temperatures in which he had many friends, there was only acclaim. One newspaper reported, "no piece has ever caused such a sensation..." In 1787, Mozart could write to his father from Prague, "Nothing is talked of here but Figaro, no opera is cared for but Figaro, always Figaro."

This achievement led to precisely what the composer needed: another commission. It may have been for Prague, not Vienna, but a job was a job. The result was Don Giovanni.

The Romantic movement and its successors imbued this opera with massive metaphysical and psychological significance. Da Ponte's problem, though, was that the story was then too well known, too mundane, too debased by years of farcical puppet plays and other popular degradations.

Further, the libretto which he freely plagiarized, a one-acter by Bertati and Gazzaniga, was too short for a full evening. Where he had been obliged to trim Beaumarchais, here he had to add much incident. As before, Mozart's music took a good professional libretto and transformed it into something worthy of the later adulation.

After the premiere, Mozart wrote to a friend, "My opera …was received with the greatest applause." But the triumph did not travel to Vienna, where Don Giovanni played only thirteen times. Da Ponte described Emperor Joseph as telling Mozart, "Such music is not meat for the teeth of my Viennese," and the composer retorting, "Give them time to chew on it!"

The sting of that tepid reception was moderated by a reasonably successful Vienna mounting of Figaro in 1789, revised to suit the local cast. It succeeded in getting work for Mozart, including a commission from the Emperor for another opera buffa.

It has been said that Joseph himself suggested the idea for Cosí fan tutte, based on current juicy gossip, but da Ponte, with nothing extant to translate or adapt, as was his normal practice, had to invent all the plot details. Its ambiguous emotional underpinnings, such as the essential immorality of the wager on the women's fidelity or the uncertainty of who loves whom when all is over, would not have scandalized contemporary Vienna, where mistresses on one hand and "boy toys" on the other remained commonplace. But this time the usual puzzled reaction to Mozart's musical sophistication, which layered sadness and parody behind the farce, was compounded by bad luck. Cosí played only five performances before Joseph's death closed all theaters. After that it appeared only intermittently across Europe until it was buried for a century by Victorian prudery.

Cosí was the last major work Mozart wrote for the Court. His finances worsened, his health declined, and his artistic output diminished drastically. Then, almost miraculously, in 1791, the last year of his life, there was an outpouring of sublime music. He had long wanted to compose another German opera; the creative freedom offered by Emanuel Schikaneder and his theater outside the city walls led to the climactic Die Zauberflöte. Here, in the face of Imperial repression, Mozart brilliantly encapsulated in symbol and musical imagery the suppressed Enlightenment Masonic ideals he venerated.

The world owes those turbulent years in the Austrian Empire a special debt. Without Joseph's initial bout of liberalism, the paths of da Ponte and Mozart might never have crossed. Had the situation not forced Mozart into needing money, he might not have written these gems. Without the safety valve of Prague, great music might have evaporated into Viennese indifference.

A variety of events coalesced, certain tumblers of history clicked into place. In the process, a decade which began in glory for Mozart left him grappling with debt, illness, and changing audience taste, but left the world infinitely richer.