An Unfinished Mass and Two Hands

In December 1791 a widow in Vienna held the unfinished score of a funeral mass and a practical problem. The mass had been commissioned anonymously, half paid in advance, and the balance depended on delivering a work the patron would accept as the dead man’s own. So Constanze Mozart did what the situation required: she gave the manuscript to a pupil of her husband, Franz Xaver Süssmayr, and he finished it in a hand trained to imitate the one that had stopped. Anyone who sets out to survey Mozart greatest works meets this problem on the first page, because the most famous sacred work in the catalogue is partly by somebody else, and two centuries of scholarship have not finished separating the two hands.

The claim this article defends is that the difficulty is not an accident of one unfinished mass but the shape of the whole catalogue. Mozart’s strongest work is concentrated in his last ten years, and within those years it is spread with unusual evenness across opera, symphony, concerto, chamber music and sacred music, so that no single composition can stand for him the way a single symphony can stand for Beethoven or a single opera for Wagner. Every shortlist of his music is therefore an argument about which genre matters most, disguised as an argument about quality. The pages that follow go through the catalogue genre by genre, work by work, giving for each major piece its circumstances, what it does that its neighbours do not, and how it was received at the time and afterwards.

That method matters because the catalogue resists the usual shortcuts. A greatest-hits approach collapses at once: the famous serenade turns out to be minor, the famous symphony turns out to be one of a pair, and the famous requiem turns out to be a collaboration conducted across a death. A chronological approach works better, and the article follows the music from the Salzburg years through the Vienna decade, but chronology keeps being interrupted by questions of evidence. Who wrote this passage? Which version did the first audience hear? Why was this piece famous in 1890 and neglected in 1990? Those questions are part of the works themselves, and they are treated here as content rather than as footnotes.

The life behind the widow’s errand, the anonymous messenger, the money and the final illness, belongs to the companion account of Mozart’s life and career, and is compressed here to what the music needs. What this article owns is the output: roughly six hundred works, one catalogue with a numbering system that misleads the unwary, five operas that anchor the modern repertory, and a sacred torso that has generated more attribution scholarship than any other unfinished work in Western music. The listening order at the end is built from the evidence assembled along the way, so a newcomer who reads straight through arrives at it knowing why each recommendation stands where it does.

The Köchel Catalogue and How the Numbering Works

Every Mozart work travels under a number preceded by the letter K, and the system is so familiar that its oddities go unnoticed. Ludwig von Köchel, an Austrian civil servant who was also a botanist and mineralogist, published his chronological and thematic catalogue of Mozart’s works in 1862, seventy-one years after the composer’s death. Working from autographs, early editions, the composer’s own partial work-list and the recollections of survivors, he arranged the output in what he believed was the order of composition and numbered it from the childhood pieces to the Requiem, which closes the book as K. 626. The catalogue was an act of rescue as well as scholarship: a substantial part of the output survived in scattered manuscripts, and Köchel gave each piece a fixed address at which scholars, publishers and performers could find it.

What is a Kochel number?

A Kochel number is the position of a work in the catalogue compiled by Ludwig von Köchel and published in 1862, which arranged Mozart’s output in supposed order of composition from K. 1 to K. 626. Later editions moved many works as dating evidence improved, so the number identifies a piece reliably but states its date only approximately.

The catch sits inside that word “supposed”. Köchel dated works by the evidence available to him, and where an autograph was undated he reasoned from style, which is exactly the kind of reasoning his own catalogue then made circular for later writers, who cited the number as proof of the date the number had merely guessed. Successive editions corrected the record as better evidence surfaced: paper studies, watermarks, handwriting analysis and newly found documents moved works forward and backward, sometimes by years. The third edition of 1937, prepared by Alfred Einstein, and the sixth edition of 1964 renumbered so many pieces that scholars took to citing two numbers for the affected works, the original and the revision, which is why a piano sonata can appear as K. 310 in one book and K. 300d in another. The numbering implies a chronology that later scholarship has repeatedly revised, and the honest way to read a K number is as an address, not as a date.

Cliff Eisen, the scholar who edited the modern documentary biography of Mozart and worked extensively on the catalogue and the sources, represents the discipline that grew up around this problem. In the Eisen view of the catalogue, a number is only as good as the physical evidence beneath it: the paper a score is written on, the copyist’s hand, the watermark that dates the sheet to a particular mill and year. That discipline is why the catalogue keeps changing underneath its stable numbering. A work can hold its K number for a century while its accepted date migrates, and the migration is not pedantry, since the whole story of Mozart’s development depends on which works stand next to which. When this article gives a date for a work, it gives the date the source scholarship supports, and treats the K number as the name of the piece rather than as evidence about when it was written.

One more consequence follows for any survey of the works. Because the catalogue counts fragments, arrangements, lost pieces known only from letters and works of doubtful authenticity alongside the masterpieces, the total it reaches is not a score to be admired but an archive to be navigated. Mozart wrote over six hundred catalogued items; perhaps a tenth of them hold the stage and the concert hall. The sections that follow spend their time where the weight of the catalogue actually rests, in the works written between 1781 and 1791, and treat the rest of the archive as the ground those works grew from.

Why the Last Decade Dominates Any Shortlist of Mozart Greatest Works

Mozart arrived in Vienna in the spring of 1781, dismissed from the Salzburg court service, twenty-five years old, and the catalogue changes character almost at once. The works of the Vienna decade include the six great piano concertos of 1784 to 1786 and the four that followed them, the Haydn quartets, the string quintets, the three Da Ponte operas, The Magic Flute, the last three symphonies, the clarinet concerto and quintet, the C minor Mass and the Requiem. Set beside that concentration, the first twenty-five years produced one opera of the first rank, Idomeneo, written just before the move, and a body of Salzburg music that specialists admire and general audiences mostly meet through a handful of pieces. Any honest shortlist is therefore a list of the Vienna decade with a Salzburg preface, and the interesting question is not whether the last decade dominates but how completely it does so across every genre at once.

The table below gathers the works on which the argument of this article rests. It is worth reading down the final column, because the entries there make the thesis concrete: each of these pieces does something that nothing else in a catalogue of six hundred works does, and they do it in different genres, for different occasions, under different constraints.

Work	Approximate date	Genre	Circumstance	What it does that nothing else in the catalogue does
Idomeneo, K. 366	1781	Opera seria	Commission for the Munich carnival	Fuses French choral and ballet elements with Italian serious opera at full length
The Marriage of Figaro, K. 492	1786	Opera buffa	First collaboration with Lorenzo Da Ponte	Turns the ensemble finale into continuous dramatic action
Don Giovanni, K. 527	1787	Dramma giocoso	Commission from Prague after Figaro triumphed there	Holds comedy and damnation in one structure without resolving either
Così fan tutte, K. 588	1790	Opera buffa	Imperial commission for the Vienna court theatre	Builds an entire opera on symmetry and tests fidelity as an experiment
The Magic Flute, K. 620	1791	Singspiel	Written for a suburban popular theatre	Joins fairground comedy to ritual scenes in a single score
Piano Concerto in D minor, K. 466	1785	Concerto	Written for the composer’s own Vienna subscription concerts	Opens the concerto with a symphonic conflict the soloist must answer
Piano Concerto in C major, K. 503	1786	Concerto	Last of the great series for his own performances	Sustains symphonic scale and ceremonial tone across a full-length first movement
String Quartet in C major, K. 465	1785	Chamber music	Published with a dedication to Haydn	Begins with a slow introduction whose clashes earned it the name Dissonance
String Quintet in G minor, K. 516	1787	Chamber music	Composed alongside its C major companion	Gives the first viola a tragic weight no quartet in the set attempts
Symphony No. 40 in G minor, K. 550	1788	Symphony	Written in a summer of rapid composition, occasion unknown	Carries an entire symphony on agitation without a slow movement of consolation
Symphony No. 41 in C major, K. 551	1788	Symphony	Last of the three symphonies of 1788	Ends with a finale that combines five themes in counterpoint
Clarinet Concerto, K. 622	1791	Concerto	Written for Anton Stadler and his extended instrument	Writes for the low notes of a clarinet that later players had to reconstruct
Mass in C minor, K. 427	1783	Sacred music	Personal vow, performed at Salzburg with his wife as soloist	Raises the Salzburg mass to monumental scale and then stops unfinished
Requiem, K. 626	1791	Sacred music	Anonymous commission, left unfinished at his death	Survives as a completion by another hand that audiences accept as his

Three engines drove the concentration. The first was the market: Vienna offered subscription concerts at which Mozart performed his own new piano concertos, so the concerto became his laboratory and his advertisement at once. The second was company: Haydn’s friendship and example pressed the chamber music upward, Schikaneder’s theatre gave the Singspiel its stage, and Da Ponte supplied libretti that made ensemble comedy possible at a new level. The third was freedom of an ambiguous kind. A court salary sets a ceiling on output as well as a floor under income, and the Vienna decade, for all its financial anxiety, let him write for whoever would pay, including patrons whose commissions he could shape to his own ends. The result is a decade in which the masterpiece rate is not a slope but a plateau, and it is the plateau, not any single peak, that a survey of the works has to explain.

The Early Works and What They Are Worth

The catalogue opens in London, where the eight-year-old Mozart wrote his first symphonies in 1764 and 1765 while his father was ill and the house was quiet enough for composition. The earliest pieces are exactly what a travelling prodigy’s portfolio required: keyboard sonatas published in Paris and London with dedications to royal patrons, symphonies modelled on Johann Christian Bach, whose music the boy had absorbed in London, and church music for Salzburg after the family’s return. Judged as documents they are astonishing, because the fluency is real and the models are handled with a sureness that musicians twice his age envied. Judged as music for a modern programme, most of them are period pieces, well made and interchangeable with the better work of the composers he was copying, which is precisely what an apprenticeship is supposed to produce.

The Italian journeys changed the scale of the ambition. Mitridate, re di Ponto, written for Milan in 1770 when Mozart was fourteen, held the stage through a long run of performances and satisfied singers famous for destroying young composers who wrote badly for the voice. Lucio Silla followed for Milan in 1772, and back in Salzburg came La finta giardiniera in 1775, an opera buffa whose ensembles already show the young composer thinking in dramatic rather than decorative terms. The five violin concertos, all from 1775, belong to his Salzburg employment as concertmaster and remain the most performed of the early instrumental works, graceful pieces whose solo writing flatters the instrument he himself played. The piano concerto in E flat, K. 271, written in 1777, stands apart from everything around it: the piano interrupts the orchestra in the first bars, a gesture no concerto had made before, and the slow movement and finale sustain the surprise. Scholars reach for it whenever the early catalogue is dismissed too quickly, because it shows the mature experimenter already present at twenty-one.

What the early works are worth, then, is twofold. As listening, a small selection rewards attention: K. 271, the last violin concerto in A major, the symphony in G minor K. 183 of 1773 with its stormy manner borrowed from the theatrical style of the time, and the Sinfonia concertante for violin and viola, K. 364, written in 1779 after the Paris journey, which belongs to no one’s apprenticeship. As evidence, the whole early output matters, because it records the most thoroughly documented musical education of the eighteenth century, tour by tour and model by model. But a survey of the greatest works should be honest about proportion. The Salzburg and travelling years fill most of the catalogue’s pages and a small fraction of its achievement, and the imbalance is itself information about what Vienna released in him.

The Salzburg Church Music

Salzburg paid Mozart to write church music, and the conditions under which he wrote it shaped the music’s character. Archbishop Colloredo, his employer, wanted brevity in the mass: settings that fitted a service without swelling into concert pieces, the so-called missa brevis manner, with the text compressed and the instruments kept modest. Mozart complied with visible impatience in the letters and with complete professional competence in the scores. The series of short masses from the middle 1770s does in fifteen or twenty minutes what Italian models did at greater length, and the best of them, including the Coronation Mass in C major, K. 317, of 1779, written for a Salzburg pilgrimage feast, achieves a public, festive brilliance inside the limits, with trumpets and timpani used as punctuation rather than wallpaper.

Around the masses sits a ring of smaller works that performers value more than the general audience knows: the two Vespers settings, K. 321 and K. 339, the second containing the Laudate Dominum whose soprano melody has travelled far beyond its liturgical home; the Epistle sonatas for organ and strings that filled the gaps in the service; and Exsultate, jubilate, K. 165, written in Milan in 1773 for the castrato Venanzio Rauzzini, a solo motet in all but name whose final Alleluia became one of the most excerpted movements of the early catalogue. Daniel Heartz, the historian whose work maps the musical institutions of Mozart’s Catholic Europe, places this output inside the economy that produced it: a court chapel was a workshop with weekly deadlines, and the young composer learned speed, scoring economy and the management of voices from obligations he later complained about. The complaint and the craft are both part of the record.

The Salzburg sacred music matters to this survey for two reasons. First, it trained the hand that wrote the C minor Mass and the Requiem, and the training shows in how economically the later works deploy chorus and orchestra. Second, it demonstrates the ceiling that employment imposed. Colloredo’s brevity rules were not philistinism; they belonged to an enlightened reform of worship that Mozart’s own instincts opposed, since his ambitions for the mass ran toward the monumental scale the C minor Mass would attempt the moment he was free of Salzburg. The church music of the Vienna years is thin by comparison, a set of small masterpieces like the Ave verum corpus, K. 618, written for a provincial choir in 1791, because Vienna paid for operas and concertos instead. Genre followed income with a fidelity that any catalogue survey has to respect.

Idomeneo and the First Mature Opera

Idomeneo, re di Creta, commissioned for the Munich carnival and first performed in January 1781, is the work in which the twenty-four-year-old composer stopped being a prodigy with a past and became a dramatist with a future. The subject, a king who vows his son’s life to Neptune and then tries to escape the vow, came with a libretto by Giambattista Varesco adapted from a French original, and the French connection matters: the Munich score absorbs the French serious opera tradition of continuous scene, chorus as protagonist and ballet woven into the action, and sets it beside the Italian aria system Mozart had mastered in Milan. The result is a hybrid that the Italian opera seria of the day could not have produced, an opera whose storm music, oracle scene and ensembles carry the drama while the arias, for all their beauty, serve a structure larger than themselves.

Julian Rushton, whose writing on Mozart treats the stage works as dramas before they are scores, hears in Idomeneo the moment the composer learned to let a scene accumulate. The great quartet in the third act, where four characters sing four incompatible emotions at once and the music holds them in a single span, is the piece’s centre of gravity: Idomeneo’s guilt, Idamante’s resignation, Ilia’s love and Elettra’s rage do not take turns, they collide, and collision of that kind is the technique the Da Ponte operas would later perfect at comic speed. Electra’s music pushes in the opposite direction, toward a fury that the conventions of serious opera were supposed to contain, and her final exit, raging against a reconciliation everyone else accepts, leaves the opera’s official happy ending deliberately scorched.

The circumstances of composition are unusually well documented because the composer, working in Munich while his father advised from Salzburg, wrote home about cuts, singers and staging with a frankness the letters rarely match elsewhere. A tenor near seventy played the king and Mozart reshaped the part around him; the castrato playing Idamante had to be taught his role note by note; the orchestra at Munich, the finest he had yet commanded, drew from him wind writing of a richness the score still advertises. He revised the work for a Vienna performance in 1786, replacing and adjusting, which gives the opera two authentic shapes and editors a standing problem. Idomeneo is performed less often than the Da Ponte operas for practical reasons, its length, its vocal demands, its serious manner, but on the evidence of the score it is the first work in the catalogue that no other living composer could have written, and any ranking of the operas that omits it has confused frequency of performance with weight of achievement.

The Abduction and the German-Language Experiment

Die Entführung aus dem Serail, first performed at the Burgtheater in Vienna in July 1782, was Mozart’s contribution to an imperial experiment: Joseph II had founded a German national Singspiel company, and the new arrival from Salzburg was expected to supply it with a success in the German language. The plot, a rescue from a Turkish seraglio complete with a humane Pasha who renounces revenge, belonged to the fashionable Turkish manner of the period, and Mozart dressed it in Janissary colour, rattling percussion and piccolo shrillness, that Viennese audiences associated with the empire’s old enemy and new fascination. Beneath the local colour the score does something more durable. It stretches the Singspiel, a play with songs, toward genuine music drama: Osmin, the comic overseer, acquires music of real menace, and Konstanze’s arias demand a virtuosity that belongs to serious Italian opera transplanted into German words.

The experiment had limits written into its institution. The Singspiel company folded within a few years, the emperor’s attention moved on, and Mozart never received a second German commission of the kind until Schikaneder’s suburban theatre asked for The Magic Flute nine years later. The Abduction therefore stands in the catalogue as a road surveyed but not travelled: proof that Mozart could build a full-length German opera that held a stage, surrounded by German works of the Vienna years that remained fragments or minor pieces. Its arias also mark a biographical turning point of a practical sort, since Konstanze’s music was written for Caterina Cavalieri, the first of the Viennese singers whose abilities Mozart composed into his scores, and the heroine shares her name with the composer’s wife, whom he married three weeks after the premiere, a coincidence the letters treat as a joke and posterity has treated as a romance.

Reception sharpened the work’s profile. The emperor’s supposed remark about too many notes, whatever its literal truth, records a real feature of the score: it is dense with invention, generous to a fault, and built by a composer testing how much music a popular theatre form could carry. The Abduction answered that question so completely that the form itself was left behind, and the German opera of the catalogue resumes only when The Magic Flute takes up the experiment under entirely different commercial conditions. Between the two works lie the Da Ponte operas in Italian, and the sequence matters for understanding the catalogue’s centre: Mozart’s operatic mastery was proved in Italian, but some of his boldest calculations about what an audience could absorb were made in German, for audiences the court considered less exalted and the box office considered more honest.

The Marriage of Figaro

Le nozze di Figaro, first performed at the Burgtheater on the first of May 1786, began as an act of tact. Beaumarchais’s play had been banned from the Viennese stage for its portrait of a servant outwitting a predatory count, and Lorenzo Da Ponte, the imperial court poet, persuaded Joseph II that the operatic version had been purged of the politics while keeping the intrigue. What the emperor licensed was the most perfectly engineered comic opera of the century: a single day of crossed schemes in a Spanish country house, in which the Count Almaviva pursues his valet’s bride, the Countess grieves and conspires, the page Cherubino desires everyone, and Figaro and Susanna defend their marriage with the tools of people who cannot afford to lose. The plot is a machine, and Mozart’s music is what makes the machine human, since the arias keep stopping the clock to let a character think, and what they think is usually at odds with what the scheme requires.

The overture sets the terms in four minutes without quoting a single theme from the opera that follows: bustle, secrecy, suppressed laughter, all in a D major that sounds like daylight. From there the first act builds through duets and trios of negotiation, each number a small transaction in the day’s economy of favours, until the act closes with Figaro dispatching Cherubino to the army in a march parody that the whole household joins. The second act raises the stakes and the temperature, introducing the Countess alone with her grief before the conspiracies resume, and it ends with the finale examined in the next section, a twenty-minute span in which seven characters and a gardener pass through accusation, denial, revelation and truce without the music once sitting down. Susanna, who sings more than anyone and schemes better than everyone, is the opera’s true centre of intelligence, and the casting of the premiere, with Nancy Storace creating the role, gave Vienna a Susanna whose artistry Mozart knew from her concert work and wrote toward deliberately.

Figaro also opens a question this article will not close until the Così section. Mozart and Da Ponte made three operas together, and posterity sorted them into a hierarchy that the eighteenth century would not have recognised: Figaro the beloved, Don Giovanni the profound, and the third, Così fan tutte, admitted to the canon late and grudgingly, defended by its admirers rather than simply celebrated. Why one of the three great comic collaborations should still need defending, when its score is by common consent as fine as its companions, is a question about audiences rather than about music, and it is held open here deliberately. The answer requires the Don Giovanni evidence as well, because the sorting of the three operas was done by the same century that rewrote all of them, and the pattern only becomes visible when the three receptions are laid side by side.

What Figaro Does That No Earlier Opera Does

The second-act finale of Figaro is the longest continuous span of music in any opera of its period, and its length is the least interesting thing about it. Earlier opera buffa had finales, chains of short sections in which the cast assembled and sang confusion in chorus. What Mozart builds instead is a single dramatic argument conducted in music: the Count bursts in on his wife, a closet door becomes evidence, accusations are made and withdrawn, a new accuser enters and reverses the polarity of the scene, a gardener arrives with a grievance about a man who jumped from a window, and the whole company negotiates its way from outrage to a truce nobody believes. Each stage changes key, tempo and metre, and each change is a turn in the argument rather than a decoration on it. The finale does not illustrate the drama; it is where the drama happens, in real time, at the speed of thought.

That is the structural invention on which the opera’s reputation ultimately rests. A finale of this kind relocates the centre of opera from the aria, where a character steps out of the action to feel, to the ensemble, where characters collide and the music must think for several minds at once. Mozart had rehearsed the technique in Idomeneo’s quartet and in the Abduction’s ensembles, but Figaro makes it the load-bearing wall of an entire evening: the third-act sextet, in which Figaro’s parentage is revealed while five other characters process the news at different speeds, and the fourth-act finale, which runs from a mistaken-identity masquerade in a dark garden to the Count on his knees, both depend on machinery the second act invented. How the machinery works at the level of phrase, key and orchestration belongs to the companion study of Mozart’s musical style, where the technique is taken apart in full; here it is enough to register that the invention is architectural, and that every ensemble opera written after 1786, from Rossini to Verdi and beyond, builds on ground Figaro surveyed.

The invention also explains the opera’s peculiar durability under changing taste. Aria styles date; plots date; a mechanism for staging several consciousnesses at once does not date, because each generation of directors finds its own content for the collisions. The Prague audience of December 1786, meeting the opera months after Vienna’s qualified success, understood the mechanism at once and made Figaro the triumph of the season, a verdict Mozart reported home with the dry satisfaction of a man whose machinery had found its proper hall. Prague’s reward was a commission, and the commission was Don Giovanni.

Don Giovanni

The Prague impresario Pasquale Bondini ordered a new opera for the autumn of 1787, and Mozart and Da Ponte gave him a work that has resisted every category offered for it since. Don Giovanni calls itself a dramma giocoso, a joking drama, and the joke keeps turning to ice: a nobleman who treats seduction as bookkeeping, catalogued by his servant Leporello in numbers that run into the thousands, kills the father of one of his victims in the opening minutes, spends the opera escaping the consequences through charm, disguise and violence, and is finally dragged below the stage by the statue of the man he murdered, unrepentant, while the survivors assemble to sing a moral that the preceding two hours have made extremely difficult to sing straight. The opera’s first Prague performance, in October 1787, was a success; its Vienna revision the following May, with new arias fitted to new singers, met a cooler house, and the divergence between the two versions has occupied editors ever since.

Simon Keefe, whose work on Mozart’s reception traces how the nineteenth century remade this opera in its own image, identifies the romantic reinvention as the decisive turn: E. T. A. Hoffmann’s essay of 1813 recast the Don as a metaphysical rebel and Donna Anna as his destined counterpart, and the reading governed productions for a hundred years, during which the opera’s comedy was played down and its ending, the final ensemble, was frequently cut as an anticlimax. The score resists the solemn reading as firmly as it resists the farcical one. The ballroom scene of the first-act finale runs three stage orchestras in three different metres simultaneously, aristocrats dancing a minuet while peasants dance a contredanse, the social order rendered as counterpoint and collapsing into attempted abduction. No solemn rebel and no mere rake presides over music that socially observant; the opera watches its hero the way its ensembles watch each other, from several angles at once, and declines to settle the account.

Practically, Don Giovanni asks more of a theatre than Figaro does: a bass-baritone who can be charming and frightening in the same phrase, a Donna Anna of genuine dramatic weight, a Leporello who is a character actor and a singer in equal measure, and stage machinery for a statue that sings and a descent into fire that must not look ridiculous. The difficulty is the subject of one of the questions answered at the end of this article, and it is real, but it is also the price of the opera’s span, which runs from a servant’s patter to a graveyard scene of sustained dread without a change of language. Within the catalogue, Don Giovanni is the work that most expands what an opera can hold; within this survey it is the second exhibit in the case that the three Da Ponte operas were sorted by their audiences, not by their scores, since the opera the nineteenth century called profound and the opera it called heartless were written by the same two men, three years apart, for the same kind of stage.

The Problem of the Ending

Don Giovanni ends twice, and the double ending has been an editorial and directorial problem for two centuries. After the Don goes down unrepentant, defying the statue to the last, the surviving characters enter and sing a concluding ensemble that draws the moral in plain terms: evildoers meet this end. For much of the nineteenth century, theatres cut that ensemble and let the curtain fall on the flames, because the moral seemed to belong to an older, simpler opera than the one audiences had just experienced. The romantic reading needed the Don’s defiance to be the last word; a sextet of survivors tidying up contradicted the metaphysics. Restoring the ensemble, as modern practice does, restores the eighteenth-century frame but creates its own puzzle, since the music of the final scene is brisk, almost cheerful, and a production must decide whether it is sincere, ironic or simply conventional, while the score supports all three decisions at different moments.

The Vienna revision of 1788 complicates the evidence further. For the Viennese cast Mozart replaced and added numbers: Elvira gained an extended scene, Ottavio a substitute aria of famous difficulty, Leporello and Zerlina a new duet, and the changes altered the opera’s balance without touching its frame. Modern productions habitually mix the Prague and Vienna materials, which means the Don Giovanni most audiences know is a composite that neither of its first two audiences heard. Editors argue the alternatives with real evidence on each side, and the argument itself is instructive for the whole catalogue: Mozart revised for singers and houses as a working professional, and the idea of a single definitive text, natural for a symphony, fits the operas badly. A works survey has to describe both shapes and say plainly that the composite tradition is a third thing, created by performance history rather than by the composer.

Underneath the editorial problem sits a dramatic one that no edition can settle. The final ensemble’s moral is sung by characters whose own conduct the opera has examined without tenderness: an Elvira who keeps returning to the man she denounces, an Ottavio whose vengeance is always postponed to a decorous future, survivors whose relief is audible. Whether Mozart intended the moral straight, as Da Ponte’s libretto prints it, or intended the audience to hear it against everything the evening has shown, is a question the music declines to close, and the refusal is characteristic. Figaro ends with forgiveness that the drama has earned the hard way; Don Giovanni ends with a formula the drama has made unusable, and lets the audience sit with the difference. The ending problem is therefore not a blemish on the opera but its last and most durable device, the point at which the work hands its judgment to the house.

Così fan tutte and Its Reputation Problem

Così fan tutte, the third Da Ponte opera, was first performed at the Burgtheater in January 1790, and its early run was cut short by the death of Joseph II, which closed the theatres in mourning. The plot is a wager. An elderly sceptic, Don Alfonso, bets two young officers that their fiancées will prove unfaithful if tested; the men pretend to sail for war, return disguised as exotic strangers, and woo each other’s betrothed with mounting success, until the experiment collapses into genuine feeling and a hasty restoration of the original pairs. The construction is symmetrical to the point of geometry: two couples, two disguises, paired arias, mirrored scenes. Julian Rushton, reading the opera as a drama of knowledge rather than of romance, points to what the symmetry does to the listener: because the situations are balanced, small differences of musical weight become the real plot, and the score keeps awarding its deepest music to feelings the experiment was designed to expose as shallow.

Why was Cosi fan tutte unpopular for so long?

Its plot was judged immoral by the century that inherited it. Two fiancées waver under a staged test, and nineteenth-century theatres, critics and composers found the premise cynical and the women degraded. Productions rewrote the story or avoided the opera entirely, so the score waited generations for a fair hearing.

What the record shows is a rejection aimed at the subject, not the music. Beethoven, who admired Mozart extravagantly, disapproved of the opera’s premise; Wagner dismissed the idea that so fine a musician should waste himself on so trivial a plot; managements that did stage the work supplied new texts, relocated plots and substitute endings to protect the audience from the original. The sidelining lasted roughly a century, and it was moral rather than musical in its grounds at every documented stage: the same decades that found Così unperformable were filling concert halls with its composer’s symphonies and publishing admiring editions of Figaro. The reassessment belongs to the twentieth century, gathering force after the middle of it, when producers began to stage the opera as written and critics, among them Rushton in his writing on the Da Ponte works, argued that the supposed cynicism is the opera’s subject rather than its attitude: the work studies how people behave when feeling is treated as an experiment, and its refusal to say whether the restored couples are happy is the honesty the nineteenth century could not use.

This closes the question opened at Figaro. The third Da Ponte opera is defended rather than celebrated because its reputation was settled by judges who objected to its premise on moral grounds and said so, in print, for a hundred years, while the score sat in plain sight accumulating the evidence for the defence. Don Giovanni was granted profundity by the same century and Figaro was granted warmth; Così was granted neither, not because its music differs in kind but because its story declined to reassure. Once the moral objection is named as the historical cause, the opera’s position in the catalogue becomes simple to state: it is the most formally daring of the three collaborations, the one whose beauty is inseparable from its discomfort, and the clearest proof in the whole works list that reception is something that happens to music, not something music earns by quality alone.

The Magic Flute and the Suburban Theatre

Die Zauberflöte opened in September 1791 at the Theater auf der Wieden, a large suburban playhouse outside Vienna’s walls, run by Emanuel Schikaneder, who wrote the libretto and played Papageno himself. The house was a commercial venture that lived on spectacle, novelty and repeat attendance, and the opera was built for it: a fairy tale with stage machinery, animals, trials by fire and water, choruses of priests, a bird-catcher in feathers, and a prince and princess whose love story shares the evening with low comedy and ritual solemnity. It succeeded immediately and durably, playing to full houses while its composer was still alive to count the receipts, a contrast with the court theatres’ treatment of his Italian operas that Mozart noted in his letters with satisfaction. The Magic Flute is the one unambiguous popular triumph of the catalogue, achieved in the last months of its composer’s life, in German, for a paying suburban crowd.

The mixture is the work’s singularity. Nobody has ever made the opera’s elements sit comfortably in one category: the Queen of the Night’s coloratura belongs to Italian serious opera at its most brilliant, Sarastro’s music to the solemn hymnody of a temple ceremony, Papageno’s songs to the popular theatre’s folk manner, and the trials to a Masonic-flavoured ritual of purification whose symbolism scholars have mapped in detail. The Freemasonry is documented fact at the biographical level: Mozart had been a lodge member since 1784, Schikaneder was a brother of the order, and the opera’s threes, its trials and its brotherhood imagery draw on the lodge culture both men knew. What the evidence does not support is the elaborate coded allegory sometimes built on those facts, a scene-by-scene cipher of Viennese politics, and this article stays with the documented connection: a network of friendship and obligation, visible in the work’s symbolism, that also functioned in Mozart’s life as patronage and community. The operas’ meaning does not need the cipher; the score’s own contrast between the Queen’s glittering rage and Sarastro’s low, slow gravity makes the argument in sound.

Within the catalogue the Singspiel completes a circle that the Abduction began. German opera, commissioned by an emperor’s cultural policy in 1782 and abandoned by that policy, returns in 1791 as a commercial proposition and produces the work by which Mozart is known to audiences who never enter an opera house for anything else. Its numbers have escaped into the general culture more completely than any other music he wrote, and its structure, popular comedy carrying ritual weight, became the foundation document of the German romantic opera that followed, whose makers said so. For a works survey, the salient fact is the range the single year 1791 displays: the same hand wrote the Clarinet Concerto, the last piano concerto, a Masonic cantata, the Ave verum and half the Requiem, and the Flute stands among them not as the light work of the year but as its most capacious.

The Late Symphonies as a Group

In the summer of 1788, between late June and the middle of August, Mozart wrote three symphonies: the E flat major, K. 543, the G minor, K. 550, and the C major, K. 551. No commission for any of them has been documented, no certain performance in his lifetime can be proved, and the letters from that summer are occupied with money, the death of an infant daughter and the logistics of a shrinking income. The triptych is the single most argued-over concentration in the instrumental catalogue, because its occasion is a blank: a composer in financial difficulty spent six weeks writing three of the largest orchestral works of the century for no customer anyone can name. The respectable explanations, a planned set of subscription concerts, a hoped-for London journey, a set intended for publication, are all conjectures fitted to the same silence, and a works survey does best to present the music as deliberately as possible and the occasion as unknown.

What unites the three is scale of ambition rather than manner. Each opens with a gesture that announces a world: the E flat with a slow introduction of ceremonial breadth, the G minor with a whisper of agitation that never leaves the work, the C major with a motto that the finale will eventually explain. Each treats the wind instruments as participants rather than colour, a habit the Paris symphony of 1778 had begun and the Prague symphony of 1786 had confirmed. And each was written by a composer who had spent the decade performing concertos in public and operas in the theatre, so the symphonies behave like dramas for orchestra, with entrances, confrontations and reconciliations conducted in themes. Daniel Heartz, placing the three works in the Viennese orchestral culture that formed their composer, notes how unusual the enterprise was in that city: Vienna consumed symphonies as concert openers and interval music, in quantity and at speed, and nobody’s career required three monumental statements in the genre in a single summer. The excess is the fact to be explained, and it has never been explained.

Their afterlife compounded the puzzle. The three were published and performed across the nineteenth century until they stood as the summit of the classical symphony before Beethoven, and the G minor in particular acquired a romantic biography of its own, read as the confession of a suffering artist on evidence the music does not supply. The version history adds a practical footnote: the G minor survives in two authentic scorings, the second adding clarinets and rebalancing the oboes, and whenever a modern orchestra plays the work it has silently chosen which of the two Mozarts of 1788 it prefers. Taken as a group, the late symphonies are the strongest instrumental argument for the thesis of this article: they are peaks, but peaks of a range that also contains the operas and concertos of the same years, and isolating them as the catalogue’s summit merely repeats the genre prejudice the works themselves refute.

Symphony No. 40 in G Minor

The G minor symphony, K. 550, completed in July 1788, opens with one of the most recognisable gestures in music: violas divided, murmuring a restless accompaniment figure before the violins enter with a melody that sighs in short phrases, each phrase answered by its own echo a step lower. The agitation is structural, not decorative. The first movement withholds repose the way a held breath withholds air; its development section drives the opening figure through a sequence of keys with an insistence that borders on the obsessive, and the recapitulation offers return without relief. The slow movement, in E flat major, provides the symphony’s only sustained calm, and even there the surface keeps stirring, the accompaniment restless beneath the long lines. The minuet is the least danceable in the catalogue, its phrases crossing the metre in syncopated arguments, and its trio’s brief pastoral is framed like a memory of a simpler world the symphony has left. The finale returns to G minor with a rocket theme and a development of real violence, in which the main subject is dismantled and reassembled at high speed, and the work ends in the key and the temper in which it began.

Two features lift the symphony out of the general run of minor-key Sturm und Drang pieces that the period produced in numbers. The first is economy: nearly everything in its four movements grows from a handful of figures, so the work feels less composed than compelled, its events following from its premises. The second is the absence of an introduction or peroration that would frame the agitation as an episode; there is no before and no after in this piece, only the state itself, sustained for twenty-five minutes. Listeners have always responded to that refusal of consolation, and their responses built the symphony’s romantic biography, in which the piece became evidence about its composer’s state of mind. A works survey should resist the biography and keep the observation: an entertainment genre, in a summer of undocumented purpose, received a symphony that behaves like a tragedy without words, and the shock is still available to any first-time listener because nothing in the piece explains or apologises.

It also rewards a comparison inside the catalogue. Mozart wrote only two minor-key symphonies, this one and the little G minor, K. 183, of his seventeenth year, and the distance between the Salzburg storm piece and the Vienna symphony measures the development of the whole art between 1773 and 1788: what the teenager borrowed from theatrical fashion, the master generates from first principles, with an orchestra half again as eloquent and a design that turns agitation into architecture. Programmers pair the two G minors often, and the pairing instructs, but it is the later work that anchors the symphony’s place in any shortlist, forty-first in the old counting of the symphonies and first in the memory of everyone who has heard it.

Symphony No. 41 and the Finale

The C major symphony, K. 551, finished in August 1788, acquired its nickname Jupiter from a London impresario’s publicity early in the nineteenth century, and the name stuck because the music tolerates it. Where the G minor is a state, the Jupiter is a ceremony: its first movement moves between a commanding motto theme and passages of lyric grace with the ease of a host who is also a sovereign; its slow movement, in F major, is a sustained meditation whose surface keeps darkening at the edges; its minuet is the most genial of the three symphonies’ dances; and then the finale performs the feat on which the work’s special fame rests. The finale is built as a sonata movement whose materials are five distinct themes, each plain enough to remember, and in the coda Mozart combines all five simultaneously in invertible counterpoint, the themes stacked above and below one another like the voices of a fugue, while the movement’s momentum never slackens into academic display.

What makes the Jupiter finale famous?

Its coda combines five separate themes at once in strict counterpoint, each theme remaining recognisable while serving as accompaniment to the others. The feat crowns a sonata movement without slowing it, proving that the learned fugue style and the public symphonic manner could occupy the same music at the same time.

The five-theme combination is the clearest proof of what the study of 1782 produced. In that year, at the Sunday gatherings of Baron van Swieten, Mozart had immersed himself in the fugues of Bach and the oratorios of Handel, copying, arranging and internalising a contrapuntal discipline that Viennese taste considered learned and obsolete. The Jupiter finale is the return on that study after six years of absorption: counterpoint deployed not as homage but as climax, in a public genre, for an audience that did not need to notice the technique to feel the accumulation. Cliff Eisen’s source work on the period underlines how deliberate the absorption was, since the arrangements for van Swieten’s circle were working exercises, made to be played and understood from inside. When the coda arrives, the listener hears five melodies behaving like five characters in a Figaro ensemble, simultaneous, independent and coherent, and the parallel is not fanciful: the symphonist and the opera composer were the same musician, and the finale is where the symphonies most openly admit it.

For the catalogue as a whole, the Jupiter closes the symphonic account with a demonstration rather than a farewell. Mozart did not know it was his last symphony; the accident of survival should not be inflated into a testament. What can be said on the evidence is that by August 1788 the instrumental works had reached a point where the most old-fashioned technique in his inheritance and the most modern public manner in his possession could be made to crown the same movement, and that no symphony written before it had attempted the combination at that scale. Its position at the head of shortlists is earned by that demonstration, even if this article’s thesis insists that the demonstration is one peak among several, in a range the last decade raised across every genre it touched.

The Piano Concertos as a Body of Work

Mozart wrote twenty-seven piano concertos across his career, and the mature twenty-three of them, from the E flat concerto K. 271 of 1777 to the B flat concerto K. 595 of his final year, form the largest single body of major works in the catalogue. The Vienna concertos of 1784 to 1786 were composed for his own subscription concerts, at which he appeared as composer, soloist and impresario in one person, and they were written at a pace that the autographs date almost week by week through the carnival seasons: three in the spring of 1784, three more by the spring of 1785, three more by the end of 1786. The series was a business model. A new concerto was an advertisement that only its composer could perform at full value, and the subscription audience that heard K. 466 in February 1785 was buying access to an event that could not be repeated by anyone else in Europe.

Simon Keefe, whose study of the concertos examines them as performances before treating them as texts, argues that the genre’s rise and fall in the catalogue tracks the composer’s performing career with unusual fidelity: the great sequence belongs to the years when Mozart the pianist could fill a hall, and the thinning of the sequence after 1786 follows the shrinking of his Viennese audience, not any failure of invention, since the last concertos, K. 537, K. 595 and the clarinet concerto’s piano contemporaries, are among the most refined scores he wrote. As a body of work the concertos also record an evolution in the relation between soloist and orchestra that no other genre of the period shows so completely. The earliest concertos converse; the middle ones debate; the greatest of them, the D minor and the C minor, stage conflicts in which the orchestra has a case of its own and the piano must answer it, and the late ones achieve a transparency in which the distinction between solo and accompaniment dissolves and reforms bar by bar.

Two practical consequences matter for a listener approaching the body of work. The first is that the concertos reward sequence: heard in order of composition across the Vienna years, they narrate a development as legible as the quartets’, and the standard portraits of individual concertos flatten what the sequence reveals. The second is that the cadenzas and the embellished repeats, left to the soloist’s improvisation in Mozart’s own performances, mean that the text as printed is deliberately incomplete at the very points where the soloist steps forward, so that every performance makes decisions the score invites. No other body of work in the catalogue builds the performer’s invention into its design so openly, and none survives so completely as both literature and script. A survey that treats the concertos as twenty-seven separate pieces misses what they principally are: the diary of a performing life, kept in the genre that life invented for itself.

The Concertos Worth Hearing First

A newcomer facing twenty-seven concertos needs a route, and the catalogue supplies natural landmarks. The D minor concerto, K. 466, is the traditional entrance, and its reputation is justified by the first minute, in which the orchestra’s syncopated unrest establishes a world the piano enters like a counsellor arriving at a crisis. The C minor concerto, K. 491, is the largest of the set, scored for the fullest wind band Mozart ever used in a concerto, and its scale makes it the symphonic pole of the series. Between the two stands the C major concerto K. 467, whose slow movement, a muted nocturne of famous serenity, has travelled so far beyond the work that hearing it in context, framed by a brilliant first movement and a bustling finale, comes as a small shock of proportion. These three, all from 1785 and 1786, give the measure of the middle period in an evening’s listening.

The later sequence changes the recommendation. The concerto in C major, K. 503, completed in December 1786, is the most ceremonially grand of the series, its first movement unfolding with a patience that assumes the listener’s full attention and rewards it; the D major Coronation concerto, K. 537, written for the Frankfurt coronation festivities of 1790, survives in a text partly unfinished in the left hand, an editorial problem that performances quietly solve; and the last concerto, in B flat, K. 595, entered in his catalogue in January 1791, replaces the public rhetoric of the great years with a conversational intimacy whose finale quotes a song about spring that he wrote the same month. Heard in that order, the six recommended concertos trace the arc of the whole body of work, from theatrical conflict to a private music that trusts the listener completely, and a reader who wants the fuller sequence can then work backward to the sparkling concertos of 1784, K. 449, K. 450 and K. 451, where the manner was invented, and forward into the wind concertos that share the late style.

It is worth saying what this selection leaves out and why. The A major concerto, K. 488, with its sighing slow movement in the unexpected key of F sharp minor, has advocates who place it above the D minor; the E flat concerto, K. 482, carries a horn colour and a festive breadth the darker works renounce; the G major, K. 453, includes a finale of variations on a theme so plain that its transformations read as a public demonstration of invention itself. The abundance is the point. Any six concertos chosen from the Vienna decade will hold together as an introduction, because the body of work was made by one performer-composer at the height of his powers for an audience he needed to astonish repeatedly, and astonishment, renewed across twenty-seven evenings, is the series’ unifying fact.

The Haydn Quartets

In September 1785 the publisher Artaria issued six string quartets by Mozart with a dedication to Joseph Haydn, and the dedication, printed in Italian in the form of a letter, is the most famous act of professional homage of the century: the younger composer presents the quartets as his children, the fruit of long and laborious effort, and commits them to the protection of the man he calls his dearest friend and the greatest composer he knows. The works behind the ceremony justify it. Composed across 1782 to 1785, in the years when Haydn’s own quartets of Opus 33 had shown what the genre could become, the set, K. 387 in G major, K. 421 in D minor, K. 428 in E flat, K. 458 in B flat, K. 464 in A major and K. 465 in C major, is Mozart’s sustained answer to his senior’s challenge, and Haydn’s verdict on the composer, delivered to Leopold Mozart in person, that his son was the greatest composer he knew in person or by name, is the dedication’s documented echo from the other side.

The labour was real and audible. The D minor quartet, K. 421, the only minor-key work of the six, sustains a tragic register through four movements that include a minuet of genuine grimness and a set of variations on a siciliano theme; the Hunt quartet, K. 458, opens with a horn-call theme in the rhythm of the chase and builds a finale of fugal energy; the Dissonance quartet, K. 465, begins with a slow introduction whose grinding chromatic clashes so disturbed early copyists that the passage was repeatedly corrected as a misprint, an anecdote that preserves the first audience’s bewilderment in documentary form. Throughout the six, the four instruments converse as equals in a manner learned from Haydn and then coloured by the opera house: themes are characters, developments are arguments, and the cello and viola, emancipated from accompaniment, take their turns at every level of the texture. The quartets also show the 1782 study at work in chamber form, fugal movements and imitative openings appearing not as learned display but as one resource among others in a conversation that can drop the technique the moment drama requires melody instead.

For the catalogue’s shape, the Haydn quartets demonstrate that the Vienna decade’s evenness extends below the level of the public genres. The same years that produced Figaro and the great concertos produced chamber music that specialists rank with Haydn’s own best, written for private performance, published as a prestige object, and received at once as classics of their kind. Their influence runs inside the genre: Beethoven, who copied out parts of the set while preparing his own first quartets, learned from both masters, and the dedication’s public framing of succession, Haydn blessing Mozart as Mozart published his homage, became the model of how the classical tradition understood its own transmission. A shortlist that stops at the operas and concertos has missed the room where the decade’s standards were set.

The String Quintets

Mozart’s string quintets add a second viola to the quartet, and the addition is not a thickening but a relocation of the music’s centre of gravity: the middle of the texture gains a voice of its own, and Mozart, who played the viola in chamber music by preference, wrote for the instrument from inside. The two great quintets of 1787 make the case in a single gesture of pairing. The C major quintet, K. 515, opens with a dialogue between cello and first violin that rises through the ensemble like a question travelling upward, and its scale, in all four movements, is the largest in his chamber music. The G minor quintet, K. 516, written in the weeks after his father’s death and in the shadow of money troubles, is its dark twin: a first movement of sustained unease, a minuet that refuses consolation, a slow movement in which the first viola’s song is muted and veiled, and a finale that begins in the minor gloom and turns, at the threshold of the last section, into a G major dance whose cheerfulness has puzzled listeners who wanted the tragedy completed rather than abandoned.

The later quintets extend the achievement into the final years. K. 593 in D major, from December 1790, opens with a theme that descends through the ensemble and builds its allegro on contrapuntal exchanges of a concentration that looks back to the Haydn quartets and forward to nothing in particular, since nobody followed him here; K. 614 in E flat, from April 1791, is the last chamber work, graceful and economical, written possibly for the same Hungarian patron who had commissioned the set. Around these four stands the earlier B flat quintet, K. 174, of 1773, and the arrangement of the C minor wind serenade as a quintet, K. 406, which testify to a lifelong interest in the medium. Yet the quintets remain the least performed of the major chamber works, casualties of programming arithmetic, since a quintet requires a guest violist and displaces a quartet from a concert that has already sold its tickets on the quartet’s name.

That neglect distorts any map of the catalogue drawn from concert life. By the testimony of the scores, the quintets are where Mozart’s chamber writing reaches its fullest sonority and its most searching expression in the same breath: the medium let him write five-part counterpoint as conversation and give the instrument he played the tragic solos. The judgement offered here is that K. 515 and K. 516 belong on any shortlist of the chamber music without qualification, and that their relative absence from programmes belongs in the underperformance account this article settles later, alongside the other casualties of convenience. The works themselves have waited out neglect before; the quintets’ nineteenth-century reputation, sustained by players rather than by publics, is an early example of the pattern.

The Clarinet Works

Anton Stadler was a clarinettist in the Vienna court orchestra, a lodge brother of Mozart, a borrower of his money and the owner of an instrument that no modern clarinet reproduces: a clarinet extended downward, the so-called basset clarinet, which gave him a low register of unusual depth. For Stadler, Mozart wrote the two works that founded the clarinet’s solo repertory. The Quintet in A major, K. 581, of 1789, for clarinet and strings, builds its serenity on the blend of the wind instrument with a string texture that parts around it like water; its slow movement is a sustained aria without words, and its finale a set of variations that tests every register of the instrument in turn. The Concerto in A major, K. 622, completed in the autumn of 1791 and the last concerto Mozart finished, takes the same partnership onto the orchestral stage, and its most famous property is its calm: three movements in which virtuosity is present everywhere and displayed nowhere, the soloist spinning long lines over an orchestra reduced, pointedly, to strings, flutes, bassoons and horns, without oboes or clarinets of its own.

The text of the concerto carries an attribution problem of the practical kind. The autograph is lost, and the first editions, prepared after Mozart’s death, adapted the solo part to the ordinary clarinet, transposing the passages that reached below its range. Performers played that adapted text for a century and a half before scholarship reconstructed the basset original from the evidence of the quintet, contemporary reports and the internal logic of the lines, and the restored low notes change the music’s character, deepening its twilight register at exactly the points where the adapted version sounds merely comfortable. The episode belongs in this survey as the domestic counterpart of the Requiem problem: here too the work the world loved for generations was a version, prepared by other hands for practical reasons, and here too the recovery of what Mozart wrote was an act of scholarship conducted from fragments and inference.

Stadler’s own story, the pawned instrument, the debts, the benefit concerts on tour with the concerto in his luggage, belongs to the biography article; the works’ survey need only register what the partnership demonstrates about the catalogue’s method. Mozart repeatedly wrote his most personal instrumental music for specific players whose hands he knew, the horn of Leutgeb, the clarinet of Stadler, his own hands at the piano, and the works carry the players’ physiologies inside them. The clarinet pieces close the account of the wind writing with an example of the principle at its purest: a repertory invented for one man and one instrument, which the whole subsequent history of the instrument has adopted as its foundation.

The Serenades and the Social Music

A large share of the catalogue was written to be played while people ate, married, graduated or took the evening air, and the serenades and divertimenti that served those occasions are usually handled in surveys as the light margin of the output. The handling is unjust to the best of them. The Haffner serenade, K. 250, written for a Salzburg wedding in 1776, runs to eight movements including a miniature violin concerto for the composer to play himself; the Posthorn serenade, K. 320, of 1779, from which Mozart later extracted a symphony, contains slow movements of a gravity that no dinner explains; and the great wind serenade in B flat, K. 361, the Gran Partita, scores for thirteen wind instruments a cycle of movements whose opening, a rising figure passed around the ensemble like light through leaves, announces music of the first rank in the clothing of an entertainment. Salieri, who conducted some of Mozart’s wind music in Vienna, is reported to have valued exactly this scoring intelligence, and the report, whatever its embellishments, points at the truth that the social works were exercises in a craft the operas also needed: how to keep sophisticated music airborne.

The serenade’s social contract shaped its forms. A serenade is a sequence, not an argument: march in, movements for listening and movements for dancing, a concert within the entertainment and then a march out, and the composer who served the form well had to grade pleasure across an evening rather than concentrate it. Mozart’s Salzburg serenades show him mastering the grading young, alternating display pieces for himself on the violin with slow movements that stop the party and make it listen, and the Vienna divertimenti and the late Nachtmusiken continue the trade in a city where the customers were aristocratic households rather than a court. The social music also had a second life that matters to the catalogue’s geography: movements migrated, serenades became symphonies, and pieces written for a name day surfaced in concert rooms, so the boundary between the social margin and the canonical centre is porous, and drawn by reception rather than by the composer.

It is here, at the serenade’s table, that the question of the next section must be opened. The most famous serenade Mozart wrote is a slight piece of 1787 that he entered in his catalogue between major works and apparently never published; it is played at weddings, in advertisements, in lifts and on doorbells, and for millions of listeners it is the sound of Mozart himself. Why the most famous serenade should tell a newcomer the least about its composer is a puzzle about fame rather than about quality, and answering it requires the little serenade to be looked at steadily, on its own terms, before it is weighed.

Eine kleine Nachtmusik and the Familiarity Problem

Eine kleine Nachtmusik, K. 525, entered in Mozart’s own catalogue on the tenth of August 1787, is a serenade for strings in four movements, originally five, one minuet being lost, lasting about eighteen minutes. It was written between the Prague journey and Don Giovanni, in the same summer as the G minor string quintet, and nothing in its history suggests that its composer valued it unusually: he sold it after his death as part of a bundle of manuscripts, his widow disposing of it to a publisher in 1799. The music itself is a perfect specimen of its kind, an opening allegro whose Mannheim rocket theme has become a universal signal for classical elegance, a Romanze of deliberate simplicity, a minuet of sturdy charm and a rondo that dispatches the evening with a grin. As craft it is flawless. As information about the composer of Figaro and the Jupiter finale, it is nearly empty, because everything in it is what the genre required and nothing in it is what only he could do.

Familiarity completes the erasure. A work becomes a logo by being excerpted, and Eine kleine Nachtmusik has been excerpted past the point of recognition: its first movement’s opening bars serve as the audio trademark of an entire art form, deployed wherever instant refinement is required, so that listeners meet the piece as a symbol before they meet it as music and rarely get past the symbol. The mechanism is worth stating because it operates across the catalogue at lower strength: the works that represent composers to the general culture are chosen by availability and adaptability, not by weight, and the representative then conceals the catalogue it represents. Mozart’s case is extreme because the gap between the logo and the output is extreme. The serenade tells a newcomer that its composer was elegant, tuneful and finished, and conceals that he was also the most dramatically daring, contrapuntally learned and emotionally unguarded composer of his century, which is why the little serenade, taken as an introduction, tells the least about him of any famous piece he wrote.

The piece deserves its defence before the section closes. Played whole, by a small string band at something like its social scale, Eine kleine Nachtmusik recovers a charm that the orchestral blow-up destroys, and its craftsmanship, phrase by phrase, is the real article, the same hand at a smaller task. The listening order at the end of this article therefore does not banish it; it places it where it functions honestly, as a palate cleanser and a measure of the distance between the catalogue’s public face and its substance. Fame, in the end, is a reception accident, and the serenade is the catalogue’s neatest proof that the most heard work and the most representative work are different categories that lazy listening confuses.

The Piano Sonatas

The eighteen piano sonatas sit awkwardly in the catalogue’s reputation. They were written across the whole career, several of them for teaching and publication rather than for the composer’s own concerts, and no single sonata has the public profile of the great concertos, because the genre in Mozart’s hands is private music, addressed to a player at a keyboard in a room, often a pupil, frequently a woman of the Viennese or Mannheim amateur world whose technique the music both flatters and extends. The early set of six, K. 279 to K. 284, written in Munich in 1775, advertises a young professional’s wares; the Paris sonatas of 1778 include the A minor, K. 310, written in the summer of his mother’s death in that city, a work whose driven first movement and relentless finale admit no pastoral consolation, and which alone among the sonatas carries the expressive weight of the major works without qualification. The A major sonata, K. 331, opens with variations instead of a sonata allegro and closes with the rondo in the Turkish manner that made it the most excerpted of the set, its fame resting on the finale the way Eine kleine’s rests on its opening.

The later sonatas refine rather than enlarge. The C minor sonata, K. 457, of 1784, published with the Fantasia in C minor, K. 475, as a single opus, is the cycle’s dark monument, its drama operatic in cut and its dedication to a pupil, Therese von Trattner, no guide at all to its contents. The famous C major sonata, K. 545, which Mozart’s catalogue describes as a little sonata for beginners, has become the most played keyboard work of the century he lived in and the gateway through which millions of piano students have met him, a pedagogical immortality the concert works cannot match. The last sonatas, K. 570 and K. 576, pare the manner down: textures thin to two and three voices, counterpoint replaces display, and the D major sonata’s opening hunting theme launches a movement whose imitative working has the Jupiter finale’s learning in miniature and in private.

The sonatas’ position in this survey is a matter of honest placement. They contain movements that any anthology of the composer must include, and two or three complete works, the A minor, the C minor with its fantasia, the D major, that stand with the best of him; but the cycle as a whole does not rival the concertos, because the public genre drew from him a sustained ambition that the teaching genre, by its nature, drew only intermittently. A catalogue whose minor cycles would be another composer’s glory is deep indeed, and the sonatas are the standing evidence that even Mozart’s intermittent ambition outlasted most composers’ sustained kind. The student grinding through K. 545 in a practice room is inside the same tradition as the subscriber at the Burgtheater, and the works know it.

The Mass in C Minor and Its Incompleteness

The Mass in C minor, K. 427, is the great torso of the sacred catalogue. Mozart began it in Vienna in 1782, in fulfilment, his letters say, of a vow made when his wife Constanze lay ill and their marriage faced his father’s opposition; in October 1783 the couple carried the unfinished score to Salzburg, where the completed movements were performed in St Peter’s church with Constanze herself singing one of the soprano parts. What exists is a Kyrie, a Gloria in seven sections of mounting splendour, a Sanctus with double chorus and a Benedictus, together with a Credo that breaks off after two movements and no Agnus Dei at all. The scale is monumental by Salzburg standards, Handelian choruses beside Italianate solos, and the soprano writing in the Christe eleison and the Et incarnatus est, the second a trio with oboe and bassoon that suspends the mass’s public grandeur for a movement of chamber intimacy, belongs to the most personal music of the Vienna years.

Why he stopped is unknown, and the conjectures divide along instructive lines. The vow was fulfilled by performance, on one reading, and the incentive died with the occasion; the Josephine church reforms, restricting elaborate service music in the capital, removed any Viennese prospect of performance, on another; the decade’s market pulled him toward opera and concerto, on a third. The record gives the facts and withholds the reason, and modern completions, by H. C. Robbins Landon, by Richard Maunder and by others, have filled the gaps with music drawn from the Salzburg masses, as the composer himself later did when he refitted much of the C minor music with a new text to make the cantata Davidde penitente in 1785. That refitting is itself evidence: Mozart valued the material enough to salvage it, and left the mass a fragment anyway.

The C minor Mass opens, in this article, the question that the Requiem will force. A listener who loves the torso must decide how much the incompleteness matters: whether the surviving movements stand alone as a performing work, whether a completion by another hand is a service or an intrusion, and by what test anyone can tell the difference when the joins are well made. Here the question is gentle, because nobody claims the completions are Mozart. At the Requiem it becomes the sharpest attribution problem in Western music, since the completed version has been loved as wholly his for two hundred years. How much of the Requiem is actually by Mozart is the question the next three sections exist to answer, and it is opened now, deliberately, over the quieter fragment, so that the test can be built before it is applied.

The Requiem Commission and the Surviving Autograph

In July 1791 an unnamed messenger, dressed in grey and refusing every question, brought Mozart a commission for a requiem mass, half the fee paid at once and the rest on delivery, with secrecy as the contract’s first condition. The patron, identified after Mozart’s death, was Count Franz von Walsegg, an amateur who bought works from composers and performed them as his own; the requiem was intended for a memorial to his young wife, Anna, who had died that February, and was to be passed off, in the count’s household and parish, as the widower’s own composition. Mozart, whose health was failing and whose imagination the anonymous errand struck with unusual force, worked on the score alongside the last operas and the Clarinet Concerto, and left it unfinished in December. What he left is the foundation of everything claimed since, and it deserves a precise description.

How much of the Requiem did Mozart write?

Mozart wrote the opening movement complete, drafted the Kyrie and most of the Sequence in vocal lines and bass with the instruments indicated, and broke off the Lacrimosa eight bars in. The Offertory movements survive in the same drafted state. Everything beyond that skeleton in the standard version was completed or composed by another hand.

The surviving autograph tells a story in physical form. The Introit, Requiem aeternam, is fully scored in Mozart’s hand, every instrument written out. The Kyrie fugue stands in the same near-complete state. Then the manner of the manuscript changes: for the Sequence, from the Dies irae through the Confutatis, Mozart wrote the vocal parts entire, the bass line, and the essential instrumental figures, leaving the filling of the orchestration to be done, as he plainly expected to do himself, in a second pass that never came. The Lacrimosa begins in that manner and stops, eight bars in, mid-phrase, at the words of weeping, and the Offertory movements, Domine Jesu and Hostias, stand in the same sketched condition as the Sequence. Here is the shareable fact of this article, and it is worth pausing on: Mozart’s own hand in the Requiem stops partway through the work, the version almost always performed was completed by his pupil Süssmayr, and the exact division between them is still argued. After the Hostias, the autograph offers nothing: no Sanctus, no Benedictus, no Agnus Dei in Mozart’s hand at all. The most famous unfinished work in music is therefore unfinished in a specific and measurable way, roughly the first half drafted by its composer, the remainder owed to the decisions of the living.

That precision matters because loose talk about the Requiem has filled the vacuum for two centuries. Legends gathered early: the grey messenger read as a visitor from the beyond, the dying composer dictating from his bed, the rival Salieri at the pillow, none of it supported by the documents, all of it dramatised until the legend became the public’s version of the work. The manuscript contradicts the legends by being businesslike. It is a professional’s working score, complete where the composer’s practice completed music first and sketched where his practice sketched, and its state tells us exactly how far the work had travelled through his ordinary process when the process stopped. Everything after that point is attribution work, not listening, and the next section names the hands that did it.

Süssmayr’s Completion

Constanze’s problem in December 1791 was contractual and severe. The count’s agent expected a finished requiem and the balance of the fee with it; a half-drafted score was worth nothing, and the widow, left with debts and two children, could not afford its worthlessness. She turned first, by the standard account, to Joseph Eybler, a respected composer and friend of the family, who began the completion, orchestrating portions of the Sequence, and then returned the manuscript, unwilling or unable to finish what another master had begun. She turned next to Franz Xaver Süssmayr, a young composer who had been Mozart’s pupil and copyist, who had lived in the household, who knew the master’s manner from inside his workshop, and whose handwriting, usefully, resembled his teacher’s. Süssmayr completed the orchestration of the drafted movements, finished the Lacrimosa from its eighth bar, and composed the Sanctus, Benedictus and Agnus Dei that the autograph lacked, closing the work by returning, for the final Lux aeterna and the Cum sanctis tuis fugue, to the music of the Introit and Kyrie, a solution he said, and Constanze confirmed, followed the composer’s own stated intention.

Christoph Wolff, whose 1994 study of the Requiem remains the closest modern reading of the autograph and its layers, argued that Süssmayr’s inheritance was larger than the surviving score shows: that sketches and drafts by Mozart for the later movements, including material for an Amen fugue intended to close the Sequence, passed through the pupil’s hands and were used or lost in the completion. The argument repositions Süssmayr from inventor to editor at several points, and it is characteristic of Wolff’s reading that the completion appears in it less as a forgery than as a workshop product, the kind of finishing a master’s shop routinely supplied. Other scholars resist the enlargement and hold to the manuscript evidence alone, on which the later movements are Süssmayr’s composition in Mozart’s manner. The dispute is live, documented on both sides, and irresolvable from the surviving papers, which is precisely why this article reports it rather than settling it.

The completion was then copied fair, delivered to the count as Mozart’s work entire, and performed under Walsegg’s name as his own composition in February 1794, while Constanze, having kept a copy, organised her own performances and sold the score to publishers as her husband’s. The deception thus ran in both directions at once, and both deceptions served the music’s survival, since without them there would have been no performable requiem for posterity to argue about. Süssmayr’s musicianship deserves the plain assessment his defenders, including the performers who keep choosing his version, have always given it: the completion is accomplished, stylistically coherent, and at its best, in the Sanctus’s brevity and the Agnus Dei’s gravity, worthy of the company it keeps. It is also, in the strictest sense, a collaboration in which one partner could not consent to the terms, and the next section measures the partnership movement by movement.

What Is His, What Is Not, and How We Know

The attribution of the Requiem can now be stated in three bands, with the evidence for each. The first band is Mozart entire: the Introit, fully scored, and the Kyrie, complete in substance. The second band is Mozart in design and another hand in dress: the Sequence movements from Dies irae to Confutatis and the two Offertory movements, where the voices, the bass and the essential ideas are the composer’s, written in his unmistakable shorthand, while the orchestral filling that clothes them was supplied by Eybler in part and Süssmayr in the main, following the indications the draft provides. The Lacrimosa sits on the border of this band, its first eight bars Mozart’s and its continuation Süssmayr’s construction from them. The third band is Süssmayr’s composition in Mozart’s manner: the Sanctus, the Benedictus and the Agnus Dei, for which no Mozart autograph exists, together with the closing movements assembled from the Introit and Kyrie music, a device both completers and widow attributed to the composer’s stated plan.

The methods behind these bands are the ordinary tools of source scholarship, and they are worth naming because the Requiem’s romance tends to dissolve them into intuition. Handwriting distinguishes the layers of the manuscript physically, Mozart’s rapid cursive against the copyists’ careful hands, and the paper itself, its watermarks and formats, dates the gatherings. The compositional logic then tests what the handwriting suggests: a passage whose voice leading, part writing and thematic working follow the draft’s implications belongs to the design even where another pen inked it, while the Sanctus, competent and correct, shows at its joins the smoother, safer habits of a talented pupil who would not risk his master’s boldness. Cliff Eisen’s documentary work on the Mozart sources supplies the discipline behind such judgments across the catalogue, the insistence that attribution is a conclusion from physical and documentary evidence, argued in the open, rather than a sensation in the listener’s ear. Listeners who believe they can hear where Mozart stops are usually hearing where the manuscript’s manner changes, which is real evidence of a kind, but it is the documents, not the sensation, that decide.

So the loop opened at the C minor Mass can close with an answer that has edges. Roughly: Mozart composed the Requiem’s first half in full or in draft, designed more of it than he inked, and wrote none of its final third as the world sings it; the exact border inside the second band, above all how much lost sketch material Süssmayr absorbed, is the question Wolff’s reading keeps open and the surviving papers cannot shut. The work that results is neither a fake nor a pure autograph but a documented collaboration across a death, and its two centuries of performance are a verdict the scholarship must accommodate rather than correct: audiences are not wrong to love the whole, and scholars are not wrong to map the parts, and the two activities have proceeded together, each sharpening the other, since the first complete edition appeared. What a works survey owes the reader is the map, drawn plainly, with the disputed border marked as disputed.

The Other Completions and the Editing Tradition

Süssmayr’s version held the field for two centuries, but it has never held it unchallenged, and the challenges themselves map the changing idea of what completion means. Nineteenth-century editors tidied the score to nineteenth-century expectations, and the Breitkopf complete edition gave the work its canonical shape while quietly regularising the completion’s rougher joins. The twentieth century brought scholars to the manuscript with fresh suspicion: the thinness of Süssmayr’s wind writing in places, the Sanctus’s brevity, the absence of the Amen fugue that the Sequence’s architecture seems to promise, all invited repair. Richard Maunder’s edition, published in the nineteen eighties, took the most interventionist line, stripping away much of Süssmayr, reorchestrating the drafted movements from the autograph’s indications and composing an Amen fugue from a sketch Mozart had left; H. C. Robbins Landon and Franz Beyer offered completions of a more conservative temper, correcting errors and lightening textures while leaving the pupil’s framework standing; Robert Levin’s version, the most performed of the modern alternatives, reworked the orchestration throughout and built its Amen fugue from the same surviving sketch, arriving at a score that presents itself as closer to Mozart’s workshop habits.

The coexistence of these editions has changed what the Requiem is, as a catalogue entry. A symphony exists in a text; the Requiem exists in a family of texts, related by a common autograph core and diverging at every point where the core falls silent, and conductors choose among them the way editors choose among the two Don Giovanni versions, by argument. Performers who stay with Süssmayr argue continuity and a certain documentary humility: his version is itself a primary source, the work as the eighteenth century delivered it. Performers who adopt Levin or Maunder argue fidelity of a different kind, to the composer’s habits rather than to his pupil’s solutions. Readers assembling presentation material for a lecture or a class on the completions, comparing the editions movement by movement, can lay the rival scores side by side in the browser-based presentation viewer and keep the argument visual. The editing tradition, in short, has not solved the completion problem; it has institutionalised it, and the institutional form, competing editions with argued prefaces, is the honest one for a work whose central fact is a join.

One consequence deserves emphasis, because it returns at the end of this article. The Requiem’s completion industry has no parallel elsewhere in the catalogue, and its existence distorts the work’s position in shortlists: the Requiem is discussed more than any other Mozart composition partly because it can be discussed forever, its evidence permanently incomplete in the most interesting place. Fame by contestability is a real mechanism of canon formation, and recognising it does not diminish the music. The drafted movements are of the first order by any test that the completed ones can be put to, and the completion, whoever holds the pen at a given bar, has carried those movements into two centuries of continuous performance, which is more than completion, in the end, is for.

Reception Then: What Succeeded and What Did Not

The first audiences sorted the catalogue differently from posterity, and their sorting is evidence a works survey must not condescend to. Vienna in 1786 gave Figaro nine performances and a mixed press before Prague took the opera up and made it the sensation of the following season; the Viennese revival of 1789, with new arias for a new Susanna, did better, suggesting that the first verdict had been about casting and circumstance as much as about music. Don Giovanni repeated the pattern in reverse capitals: Prague, which had commissioned it, was delighted, and Vienna, receiving it in 1788 with alterations, was puzzled. Così fan tutte had its first run amputated by an emperor’s death and the closed theatres of the mourning, an accident of reception that followed the opera for decades, as though the short run had been a judgment. The Magic Flute, by contrast, succeeded at once, completely and in public, the one opera whose first reception matches its settled reputation, and it did so outside the court system altogether.

The instrumental works met a parallel sorting. The piano concertos were successes of occasion, tied to their composer’s performances, and their texts circulated slowly, several unpublished for years; the subscription audience that heard them was buying the performer as much as the pieces, and the pieces’ independent career had to wait for publication and for other pianists. The symphonies of 1788 have no documented first reception at all, the strangest silence in the catalogue, and were taken up by the concert life of the following decades as the publishing industry in orchestral parts grew up around them. The chamber music fared best in print: the Haydn quartets were received as classics on publication, reviewed with respect and bought by the amateur market they were designed to honour, so that the most private genre enjoyed the most immediate public ratification. Canon formation across the whole output, visible in miniature in these contrasts, followed the channels of print, performance institutions and anecdote rather than any direct perception of quality, a pattern the wider survey of the history of classical composers traces across the period.

Two Salzburg judgements complete the contemporary picture. The church music was received as duty excellently performed and travelled little, since its institution owned it; the early Italian operas were received as prodigies’ work and travelled as reputation rather than as repertory, Mitridate’s long Milan run notwithstanding. Idomeneo, the masterpiece of the pre-Vienna years, waited longest of all for its due, admired by musicians who could read the score and largely unperformed through the century that canonised the rest. Reception then, in sum, ratified the popular theatre piece, honoured the chamber music, misplaced the greatest serious opera, and left the greatest symphonies in a drawer. No reader who has followed the argument this far will expect reception since to have simply corrected the account, and the next section shows the corrections and the new errors arriving together.

Reception Since: What Rose and What Fell

The nineteenth century rebuilt Mozart in its own image, and the rebuilding raised some works by burying others. Don Giovanni rose highest: Hoffmann’s romantic reading made it the century’s metaphysical opera, and its hero’s damnation, which the eighteenth century had framed with a moral ensemble, became the point of the work. Figaro held its place by warmth rather than by metaphysics, the opera of human sympathy in a century that valued the category. The symphonies and concertos entered the orchestral canon as the classical standard against which the romantic symphony measured itself, and the Requiem acquired its cult, performed at the funerals of composers and statesmen until the unfinished mass for an anonymous count’s wife had become Europe’s public music of mourning. Against these rises stand the falls. Così fan tutte, as its section showed, was pushed out of the repertory on moral grounds and survived the century in bowdlerised adaptations. Idomeneo slept. The string quintets receded into players’ affections. The Salzburg church music was catalogued and largely unheard.

The twentieth century corrected the account along lines its own values dictated. The complete edition and the paperback score put the whole catalogue into scholars’ and students’ hands, and the recording industry, which needed repertory beyond the famous dozen works, mined the archive systematically: complete cycles of the concertos, the quartets, the sonatas, the church music, until the recorded Mozart dwarfed the performed one. Così returned to the stage entire and was recognised, within a generation, as a masterpiece whose rehabilitation required no apology. Idomeneo was revived and recorded by conductors who treated the score’s French grandeur as an asset. The historically informed performance movement then re-sorted the catalogue once more, shrinking orchestras, restoring the fortepiano to the concertos and Stadler’s long clarinet to the concerto written for it, and in doing so made the works sound, to many ears, newer than the tradition had left them. Which of these receptions was the recovery and which the new distortion is a question the downstream account of Mozart’s influence on music takes up in full, since influence and reception are the same river seen from different banks.

Two lessons stand out for the purposes of this survey. The first is that the catalogue’s centre of gravity has moved repeatedly without the catalogue changing at all: the notes are stable, the canon rotates, and each rotation is datable to a change in the audience’s institutions, its media or its morals. The second is that the works most damaged by rotation are those whose value a rotation cannot see: the opera condemned for its premise, the mass admired in excerpt, the quintets loved by the people who play them and passed over by the people who programme them. A shortlist built from settled reputations inherits all the rotations at once and calls the inheritance taste. The final sections of this article try to do better: first by naming the works the rotation has left behind, and then by proposing a listening order built from the music’s own geography rather than from its fame.

The Works That Are Underperformed

Underperformance is a measurable condition, not a mood: it is the distance between a work’s standing among those who know the catalogue and its frequency in the programmes of those who present it. By that measure the catalogue’s clearest casualty is Idomeneo, a major opera by the consent of every conductor who has staged it, performed a fraction as often as the Da Ponte works because it demands a large cast, a chorus, a ballet tradition and a tenor hero in a style the modern repertory neglects. Beside it stand the string quintets, examined earlier, whose exile is a matter of booking arithmetic, and the Mass in C minor, which appears in concert seasons as a torso with borrowed completions and suffers in prestige from the amputation it wears openly, while the Requiem, identically incomplete, profits from its mythology. The comparison is uncomfortable and instructive: incompleteness is forgiven where legend assists it and taxed where it does not.

The second rank of the neglected is stocked with works whose genres fell from fashion. The concert arias, written for specific singers at specific concerts, include pieces of the first quality that no modern institution has a slot for, since the aria recital itself has vanished. The early symphonies beyond the little G minor wait in the shadow of the last three; the piano concertos of 1784, K. 449 to K. 451, are outplayed by their successors of 1785 and 1786 in a ratio their quality does not explain; the divertimenti and the church sonatas survive as filler at the edges of programmes devoted to other things. Even within the famous genres the rotation picks favourites: of the last three symphonies the E flat, K. 543, generous and ceremonial, is programmed least, and of the Da Ponte operas Così, restored to honour, is still the first cancelled when a season’s budget tightens. Neglect, in the catalogue’s economy, is rarely a verdict on the neglected; it is the sum of costs, customs and slots.

Naming the underperformed has a point beyond fairness. The works a survey recommends determine the works a reader hears, and a greatest-compositions article that merely ratifies the famous dozen has added nothing but length to the world’s stock of programme notes. The argument of this article, that the catalogue’s glory is its evenness, implies a duty to route attention downward into the catalogue’s less visited rooms, where the same workmanship operates at the same level under worse publicity. The listening order that follows is built under that duty: it assumes a reader who knows the famous overtures and the little serenade, and it spends its recommendations where they will change what that reader can hear.

A Listening Order for a Newcomer

Begin with Figaro, whole, in a performance with the words understood, because the opera teaches the catalogue’s central skill, following several minds at once, while delighting a first-time listener enough to fund the rest of the journey. Move next to the piano concertos K. 466 and K. 491, where the same dramatic thinking wears orchestral dress, and then to the Jupiter symphony, whose finale will now sound like an ensemble that has learned to sing without voices. The Haydn quartet K. 465 and the G minor quintet, K. 516, come next, chamber music of operatic cut, and then the G minor symphony, whose agitation the quintet has prepared the ear to follow. At that point the reader owns the catalogue’s grammar, and the order can loosen: Don Giovanni for the summit of the dramatic art, the Clarinet Concerto for its valediction, the C minor Mass for the sacred manner at full stretch, and the Requiem last among the famous works, heard with the map of hands drawn in this article open beside the score.

Which Mozart opera should I see first?

The Marriage of Figaro. Its plot is clear, its comedy lands without preparation, and its ensembles teach the listening skill every other Mozart opera requires. A good production makes three hours pass like one, and the newcomer leaves owning the grammar of the Da Ponte works before meeting their darker companions.

Practical counsel belongs in a listening order as much as taste does. Keep notes as the sequence unfolds, because the comparisons this article has been making, between versions, completions and genres, become the reader’s own property only when they are recorded while the hearing is fresh; readers who keep their listening notes in an offline notebook can take the VaultBook download page as the source of an offline encrypted notes app suited to exactly that private, cumulative work. Choose recordings by completeness before celebrity in the operas, since a cut Figaro teaches a false grammar; in the concertos, prefer performances that let the wind instruments speak, because Mozart’s wind writing is where the drama hides; and hear at least one work on period instruments early, not as a doctrine but as a control, so that the modern orchestra’s splendour is recognised as a choice rather than mistaken for the music itself. The order proposed here is one defensible path among several, and its defence is the article’s: it follows the genres in the sequence that makes each next step intelligible, and it arrives at the contested works with the evidence already in the ear.

Why No Single Work Stands for Him

The survey ends where its thesis began, with the Requiem in one hand and the catalogue in the other. Mozart’s strongest work is concentrated in a single decade and distributed across every genre that decade offered him: the opera house claims Figaro, Don Giovanni and the Flute; the concert room claims the piano concertos and the last symphonies; the chamber claims the quartets and quintets; the church claims the C minor Mass and the contested Requiem. Because the strongest work is spread so evenly, any shortlist is really a statement about which genre matters most, and the honest response to the question of his greatest composition is to ask the questioner which room of the house they live in. The comparison with the other summits of the tradition, set out in the series survey of the greatest composers of all time, shows the same structure from farther off: Bach can be met in a single mass, Beethoven in a single symphony, Wagner in a single opera, and Mozart in nothing smaller than a shelf.

That evenness is not the absence of peaks. It is a different shape of greatness, produced by a specific career: a freelance decade in a capital that paid by the genre, a technique formed by the opera house and the church and the subscription platform at once, and a working life so short that the peaks had no decades of decline around them to make one period stand for the man. The Requiem’s divided authorship, with which this article opened, is the emblem of the whole survey in a sense its legends never intended. Even the catalogue’s most famous single work refuses to be single: it is two composers, a widow’s contract, a count’s vanity and a century of editors, gathered into one score that audiences rightly love. A catalogue that will not reduce to a work will not reduce to a list either, and the six hundred K numbers, misleading, revised and indispensable, remain the only honest table of contents for the most evenly distributed genius in Western music.

Frequently Asked Questions

Q: What are Mozart’s most famous works?

The fame list is stable across two centuries: the operas The Marriage of Figaro, Don Giovanni and The Magic Flute; the last symphonies, above all the G minor, K. 550, and the Jupiter, K. 551; the piano concertos in D minor, K. 466, and C minor, K. 491; the Clarinet Concerto, K. 622; Eine kleine Nachtmusik; and the unfinished Requiem, K. 626. Fame, though, is a poor map of the catalogue. The list omits the string quintets, the Mass in C minor and Idomeneo, which musicians rank with the famous dozen, and it includes the little serenade, a charming occasional piece that represents its composer the way a signature represents a book. A reader who knows only the famous works knows the catalogue’s public face. The works behind that face, spread evenly across opera, concert hall, chamber and church, are the subject of the survey this question closes, and the listening order offered there is built to move a newcomer from the famous list into the fuller one without wasting the fame that brought them.

Q: How many works did Mozart write?

The Köchel catalogue lists more than six hundred items and closes with the Requiem at K. 626, but the number is a count of entries, not of finished compositions. The entries include fragments abandoned at every stage, works lost and known only from letters, arrangements of other composers’ music, pieces written jointly or doubtfully attributed, and the childhood exercises of a prodigy whose father kept everything. Finished, mature works of substance number far fewer, and the works that hold the modern repertory fewer still, perhaps forty or fifty. The count also depends on decisions about what constitutes one work: a serenade of eight movements, an opera of thirty numbers and a piano sonata each stand in the catalogue as a single entry. The honest answer is therefore layered. Mozart’s catalogue contains over six hundred numbered entries; his output of completed major works fills the last fifteen years of a thirty-five-year life; and the concentration of masterpieces in the Vienna decade, between 1781 and 1791, is the statistic about his productivity that actually describes the music.

Q: How does the Kochel catalogue order the works?

Köchel arranged the works in what he believed was the order of their composition, numbering them from the childhood pieces of the seventeen sixties to the Requiem of 1791, and documented the evidence for each work’s date. The order was an educated reconstruction: where autographs were dated the sequence was firm, and where they were not, Köchel reasoned from style, paper and testimony, while later scholarship, armed with watermark studies and new documents, has moved many works from the places he assigned them. Alfred Einstein’s third edition of 1937 and the sixth edition of 1964 renumbered so extensively that affected works carry two numbers in scholarly use, the original K number and the revised one, written K. 310 and K. 300d for the same sonata. The catalogue orders the works by a chronology that is corrected beneath a numbering that stays fixed for convenience. A K number identifies a work the way a shelf mark identifies a book; the date printed beside it is scholarship’s best current judgement, not a fact the number itself guarantees.

Q: What is The Marriage of Figaro about?

The opera compresses one day of intrigue at the estate of Count Almaviva, who intends to exercise a feudal claim on Susanna, the bride of his valet Figaro, on her wedding day. Susanna, Figaro and the Countess, mourning the love her husband once had for her, conspire in shifting alliances to trap the Count into public embarrassment and renewed fidelity, while the page Cherubino pursues every woman in the house and the older generation, Marcellina, Bartolo and Basilio, press claims of their own that turn out to involve Figaro’s unknown parentage. Beaumarchais’s play had been a political scandal for showing a servant humiliating a master; Da Ponte’s libretto softens the speeches while the music restores the balance from inside, giving the Countess the opera’s most dignified grief, Susanna its quickest intelligence and the Count a charm that makes his defeat enjoyable rather than merely just. It ends with the Count on his knees asking forgiveness, the Countess granting it, and the household dancing: the social order repaired by the people it had wronged.

Q: Why is Don Giovanni considered difficult to stage?

The opera demands several incompatible things at full strength. Its title role requires a singer who can charm, threaten and joke in one scene and then face a singing statue without melodrama; Donna Anna needs dramatic weight and Donna Elvira tragic intensity inside a comic frame, and Leporello must be a complete character actor. The staging must manage a ballroom scene with three orchestras playing different dances at once, a supper interrupted by a stone guest and a descent into fire that collapses if it looks cheap or merely spectacular. Above the logistics sits the tonal problem: the work is a comedy that contains a murder and a damnation at its close, and every production must decide, scene by scene, how much of each register to play, with the score supporting contradictory decisions. Houses also inherit two versions, Prague and Vienna, and must choose or conflate them. The difficulty is not one problem but a stack of them, vocal, scenic, editorial and interpretive, and it is why the opera fails more interestingly than most successes.

Q: What is the Magic Flute’s relationship to Freemasonry?

The connection is documented at the level of persons and symbols rather than as plot. Mozart joined a lodge in 1784 and remained a Mason, composing cantatas and songs for lodge occasions; Schikaneder, the librettist and first Papageno, was also a brother of the order, and the work’s first patrons moved in the same circles. Inside the opera, the symbolism is conspicuous: the number three governs ladies, boys and trials; the action moves from darkness and a vengeful queen toward a brotherhood of light, wisdom and tested virtue; the trials by fire and water resemble initiatory ordeals; and Sarastro’s order admits the hero after examination. What the evidence does not establish is the allegorical key that some writers have proposed, in which each character stands for a Viennese figure and each scene encodes a political event. Scholars treat that construction as speculation. The defensible summary is that two Masons made an opera saturated in the imagery, ethics and ritual shape of their lodge culture, for a public theatre whose audience included many who recognised that.

Q: What makes the late symphonies different from the early ones?

Scale, independence and intent divide them. The early symphonies, written for Salzburg and the tours, follow the period’s entertainment design: three or four movements, strings carrying the argument, winds doubling or colouring, a span suited to opening a concert or filling an interval. They are accomplished and striking, as the G minor symphony of 1773 shows, and they behave like the best of their kind rather than like a new kind. The last three symphonies of 1788 assume a listener’s attention for half an hour. Their wind parts converse as equals with the strings; their developments argue at length; their slow movements sustain meditation rather than contrast; and the Jupiter finale performs feats the early works never attempt. Behind the differences lies a change of employer: the late symphonies were written without a commission, by a composer who had spent a decade writing operas and concertos for Vienna, and they import the drama of those genres into the symphony, which the early works, written to order inside a court Kapelle, had no mandate to do.

Q: How many piano concertos did Mozart write?

Twenty-seven, by the standard numbering, spanning his career from the childhood arrangements of other composers’ sonata movements to the B flat concerto, K. 595, of the last year. The count includes four early concertos assembled at age eleven from movements by composers his father set before him, three Salzburg concertos that begin his independent work in the form, and the great series of the Vienna decade, in which he composed concertos for his subscription concerts as fast as the carnival seasons demanded them. The mature series is the heart of the matter: from K. 271 of 1777, the first characteristic example, the concertos run in a near-continuous line through the dozen masterpieces of 1784 to 1786 to the sparser, more intimate works of the final years. No other body of concertos from the period approaches the set in number or in quality, and portraits of the genre treat these twenty-seven as its classical foundation, the point where the concerto became a drama between a soloist and an orchestra rather than a display over an accompaniment.

Q: Why are the Haydn quartets dedicated to Haydn?

Because Haydn had shown what the string quartet could be, and the dedication says so in the language of family. Haydn’s Opus 33 quartets, published in 1782, reinvented the genre as a conversation of equals, and Mozart, who heard them as a colleague rather than as a pupil, spent three years answering them with six quartets. When Artaria published the set in 1785, Mozart prefaced it with a letter to Haydn presenting the works as his children, the fruit of long and laborious effort, and asking Haydn, as the greatest authority alive, to protect and judge them. The compliment was strategy and truth at once: Haydn’s endorsement, which came in person when he told Leopold his son was the greatest composer he knew, carried the set into the European market, and the quartets’ quality justified the ceremony. The dedication also fixed the tradition’s account of its succession, the senior master blessing the junior, a scene Beethoven would later re-enact when he dedicated his first quartets to a world Haydn and Mozart had made.

Q: Who completed the Requiem?

Franz Xaver Süssmayr, Mozart’s pupil and copyist, delivered the completed score the world has performed since, but the completion had two stages and a false start. Constanze Mozart first gave the manuscript to Joseph Eybler, who orchestrated part of the Sequence and then returned the work unfinished. Süssmayr then took over: he completed the orchestration of the movements Mozart had drafted, finished the Lacrimosa from the point where the autograph breaks off, and composed the Sanctus, Benedictus and Agnus Dei, for which no Mozart manuscript exists, closing the mass by reusing the music of the Introit and Kyrie for the final sections, a procedure he and the widow said followed the composer’s expressed intention. Christoph Wolff’s study argued that Süssmayr worked with more of Mozart’s sketch material than the surviving score shows, which would make parts of his completion partly the master’s; other scholars hold to the documents alone. The accurate short answer is Süssmayr, with Eybler’s abandoned attempt before him and a scholarly dispute about his materials behind him.

Q: How do scholars separate Mozart’s hand from Sussmayr’s?

They begin with the physical manuscript. Mozart’s autograph is written in his rapid cursive, and its layers can be read: full score for the Introit, then vocal parts, bass line and instrumental indications for the movements he drafted, stopping eight bars into the Lacrimosa. The completions appear in other hands, and paper studies, watermarks and gathering structure date and order the sheets. Beyond the handwriting, scholars test the music itself against the draft’s implications, asking whether an orchestrated passage follows the figures Mozart sketched, and against the known habits of the pupil, whose authenticated works supply a control sample of his manner. Christoph Wolff’s reading of the autograph added a third line of evidence, arguing from the manuscript’s state that Mozart left sketches for later movements which Süssmayr used and which are lost. Where the documents speak, attribution is firm; inside the Sequence’s orchestration and across the sketches, it remains a matter of argued probability. No single test decides the border, which is why accounts give the three bands of certainty rather than a line.

Q: Are there other completions of the Requiem?

Several, and choosing among them is a decision performers must keep making. Süssmayr’s version, the completion delivered to the patron, dominated for two centuries and remains the most performed. Franz Beyer’s edition of the nineteen seventies kept Süssmayr’s framework while correcting errors and lightening the orchestration editors had thickened. H. C. Robbins Landon offered a completion of a similarly conservative temper. Richard Maunder went further, discarding much of Süssmayr, reorchestrating the drafted movements from the autograph’s indications and composing an Amen fugue to close the Sequence from a sketch the composer left. Robert Levin’s completion, the most widely adopted of the alternatives, reworked the scoring throughout in the direction of Mozart’s orchestral habits and built its Amen fugue from the same sketch. The differences among the editions are largest where Mozart’s draft is thinnest, in the movements he never reached, and smallest in the drafted Sequence, where all completers serve the same master text. A listener comparing recordings should therefore check the edition as carefully as the conductor, since the notes change with the choice.

Q: Should I start with opera or instrumental music?

Start where your habits live, because the catalogue rewards entry at any door and punishes forced marches. A listener who reads stories and watches theatre should begin with The Marriage of Figaro, whose ensembles teach the listening that all the operas require, and proceed to Don Giovanni when the grammar feels natural. A listener at home in orchestral music should begin with the G minor and Jupiter symphonies and the D minor piano concerto, where the same intelligence works without voices, and come to the operas with those scores in the ear. A chamber music listener has the Haydn quartets and the G minor quintet as its gate. The one poor starting point is the catalogue’s logo, Eine kleine Nachtmusik, which charms without instructing, and the one poor method is chronology from the childhood works, an apprenticeship tour that delays the masterpieces for weeks. Whichever door is chosen, the destination is the same spread: a newcomer is not educated in Mozart until opera, concerto, symphony, chamber music and sacred music have each had a hearing.

Q: Is Eine kleine Nachtmusik representative of Mozart?

It represents his craftsmanship at its most polished and his imagination at its least engaged: a misleading ambassador. The serenade, K. 525, written in 1787 between the Prague journey and Don Giovanni, is the serenade at its most polished: balanced phrases, assured string writing, a singable Romanze, a minuet and a witty rondo, inside eighteen minutes. Nothing in it misrepresents the composer’s technique. What it omits is everything that distinguishes him from his contemporaries: the ensembles, the contrapuntal learning, the searching of the G minor quintet written the same summer, the scale of the works around it. Its fame is a product of excerpting, since its opening bars became the sign for elegance in broadcasting and advertising, until the trademark replaced the piece. Heard at the scale of a string band rather than an orchestra, it recovers its charm and reads as what it is, a master at a small task. As a summary of Mozart, it should be trusted the way a passport photograph is trusted: accurate, and no substitute for meeting the person.

Q: How do I follow an opera without knowing the language?

Work in layers, and let the music do more of the carrying than beginners expect. Read a synopsis scene by scene, so that entrances and confrontations arrive as confirmations rather than surprises. Follow the surtitles or a libretto translation with a light hand, glancing for a passage’s sense rather than reading every line, because the drama in Mozart is carried by ensembles whose meaning lives in who is singing against whom, and the eye is needed on the stage when the alliances shift. Listening to a recording beforehand, once, with the translation open, fixes the ensembles in the ear and pays for the ticket repeatedly. Choose a production that tells the story plainly, and prefer completeness to casting, since a cut score breaks the chain of causes that makes the finales intelligible. Knowledge of the language enriches hearings, but the operas were built for houses following plots in translation, in adaptation and sometimes in ignorance, and they assume a listener who is being told the story by the music as much as by the words.

Q: How do I compare two recordings of the same concerto?

Compare decisions, not reputations, and compare them at the same passages. Choose three points in the work, the orchestra’s opening statement, the soloist’s first entry and the slow movement’s main episode, and hear each recording at those points, noting tempo, the balance between piano and winds, and how much the soloist decorates the line. Attend to the cadenza, the soloist’s display near the movement’s end: whether it is Mozart’s cadenza, another composer’s or the performer’s invention tells you the performance’s sense of duty to the text. Note the instrument where it matters, a fortepiano’s clarity against a grand’s weight, and the orchestra’s size, since a chamber band lets the wind writing speak where a large one gilds it. Context completes the comparison: a recording from the nineteen fifties documents a tradition as much as a work, and judging it by period practice standards misses what it offers. The aim is not a winner but a map of the choices the score permits, after which preference becomes a position rather than a taste for names.

Q: Which five Mozart works give the best overview?

Choose by genre, since the catalogue’s distinction is its evenness, and five from one genre misrepresent it however fine they are. For opera, The Marriage of Figaro, the complete Mozart in an evening of comedy. For the concerto, the D minor Piano Concerto, K. 466, where soloist and orchestra conduct a drama of equals. For the symphony, the Jupiter, K. 551, whose finale gathers the contrapuntal learning of the decade into triumph. For chamber music, the String Quintet in G minor, K. 516, the most searching of the chamber works. For sacred music, the Requiem, heard with the knowledge that its completion was a musician’s act of loyalty, which is part of its story rather than a scandal. Together the five span 1785 to 1791, Vienna’s theatre, concert room and church, and every relationship of his art: with a librettist, with an orchestra, with four colleagues in a room, and with the dead. A listener who knows the five owns the map; the rest of the catalogue is the territory, and it repays the walking.

Q: What should I listen for in a piano concerto?

Listen for a negotiation. The orchestra opens by stating the movement’s material in public form, and the piano’s first entry is the event to attend to: whether it agrees with the orchestra’s version, decorates it, contradicts it or changes the subject tells you the concerto’s dramatic premise in the first minutes. Follow the wind instruments through the tuttis, because Mozart writes arguments into the woodwind choir that the strings merely frame, and the soloist often answers a wind phrase rather than the full band. In the slow movement, notice the relation between the piano’s singing line and the accompaniment’s restraint, the aria translated to the keyboard. In the finale, a rondo in most of the great concertos, track how each return of the refrain is altered by what has happened since its last appearance. Reserve attention for the cadenza, where the action pauses and the soloist speaks alone: it is the concerto’s confession scene, and in Mozart’s hands, even when improvised by another century’s pianist, the point at which the negotiation becomes personal.

Q: Which Mozart works are underperformed today?

Idomeneo heads the list, an opera kept rare by its size, manner and demands on a tenor and a chorus, followed by the string quintets, whose exile is caused by hiring a fifth player. The Mass in C minor is performed as a fragment and judged as one, while the Requiem, no more complete, is protected by its legend; the E flat symphony, K. 543, is programmed less than its two companions of 1788; the piano concertos of 1784 wait in the shadow of the set that followed them; and the concert arias, written for singers of a vanished institution, have lost the house that used to hold them. The pattern is consistent: the neglected works are neglected for reasons of cost, custom and slots, not because musicians who know them rate them lower, and several, the quintets above all, are rated by players at the top of the catalogue. A listener who wants the composer should treat the list of the famous as a beginning and take the absences in this answer as assignments.

Q: How did audiences respond to Mozart’s works at the time?

Differently in every city and genre, which is the first fact to hold. Prague adored Figaro months after Vienna had received it politely, commissioned Don Giovanni on that strength and made its premiere a triumph, while Vienna, hearing Don Giovanni revised, was reserved. The Magic Flute’s audience responded with enthusiasm, returning weekly until the opera passed a hundred performances within a year of the composer’s death, a success the court theatres had never given him. The piano concertos delighted the subscription audiences they were written for, and the delight attached to the performer, which is why the works’ reputation waited for publication. The Haydn quartets were received by the connoisseurs who bought them as the classics they are, the most immediate ratification any of the works received. The late symphonies left no first reception on record at all. Posterity should resist speaking of his contemporaries as a jury that failed him: some recognised everything, some recognised the performer and missed the works, and the works that were missed were missed in silence, not in scorn.