The most haunting likeness we have of Mozart is an incomplete portrait. Dating from his early years in Vienna, the painting (by Joseph Lange, who married the woman Mozart once loved and was rejected by) captures him in a moment of intimate meditation at the keyboard. Its unfinished state is a remarkably apt - if unintended - metaphor for the ways in which each generation finds that it must fill out its own image of Mozart, according to its particular needs and tendencies.

The flood of new books, recordings, and live performances unleashed during the composer's 250th anniversary year is an index of his enduring fascination. Such a renewed focus is testimony that, with Mozart, there can be no all-inclusive, final word. And this summer's Mostly Mozart Festival, from July 28 to August 26, is intent on placing special emphasis on his open-ended significance.

When you think of our world of sound bites and instant gratification, with its extraordinarily accelerated rate of change," observes Jane S. Moss, the Festival's Artistic Director, "it's all the more astonishing that Mozart is as relevant today as when he lived over two centuries ago. That's why Mozart, more than any other composer, lends himself to this kind of continual reinterpretation."

Part of this takes the form of new works commissioned by Lincoln Center to reflect the engagement of contemporary artists with Mozart's music (along with such events as Concerto Köln's late-night concerts in The Allen Room, which will team it with the world-music ensemble Sarband on August 11-12). But this year's Mostly Mozart Festival is also exploring lesser-known facets of Mozart's operatic genius. Two operas anchored in the Enlightenment - the unfinished, rarely encountered Zaide (in the U.S. premiere of a new production by Peter Sellars) and the opera seria Idomeneo (given a semi-staged account led by William Christie and his ensemble Les Arts Florissants) - reveal aspects of the composer that might surprise even seasoned Mozartians.

An extraordinary period of artistic self-discovery and synthesis gave the young Mozart confidence to push his dramatic vision in these works to new extremes. As a result, they not only transcend the conventions of their time, but - if we allot them the attention they deserve - strike a note of uncanny resonance for today's world.

The destruction of cities, the enslavement of populations, the dilemmas and evasions of rulers, the tragic consequences of their mistakes," as the critic David Cairns writes, "are no longer far-off events with no power to touch us. Thanks to the genre-transcending intensity of Mozart's music, they touch us to the quick."

Zaide offers an especially tantalizing glimpse into the period when Mozart, just in his early 20s, was consolidating his mastery of opera, the art form into which all his enthusiasm, intuition, and expertise flowed. As a nearly completed work (put aside on account of external factors), never to see the stage in Mozart's lifetime, Zaide has been dismissed as a mere study which would find perfection in its comic counterpart singspiel, The Abduction from the Seraglio. Even the title Zaide is an interpolation by its 19th-century publisher, since the autograph score lacks one.

Yet Zaide is far more than a sketch. It's a magnificent torso in which the touch of the master is already present. Moreover, according to Louis Langrée, Music Director of the Mostly Mozart Festival, Zaide forms "part of a continuum" with other stage works from the same period in Mozart's life, including his score for Thamos, King of Egypt and the opera whose commission preempted Mozart's work on Zaide, Idomeneo.

Both Zaide, which is possibly based on a story from Voltaire, and the reworking of Greek myth in Idomeneo reveal a humanist concern for addressing cultural clashes and the oppressive social order they encourage. Zaide draws on the conflict between the West and the Muslim world (reconfigured by Peter Sellars as taking place in a sweatshop in our era of globalization), while the Greeks' victory over the Trojans becomes the catalyst for the tragic conflict at the center of Idomeneo. "The message from Mozart is always about reconciliation, compassion, and dignity," notes Langrée. It becomes the shared backdrop to these pivotal operas in which he was establishing his mature reputation as a composer of theater music.

Mozart's experimentalism in these works occurs on two levels: in the theatrical message and in the orchestration," Langrée points out. The dramaturgy of Zaide (in which Langrée conducts Concerto Köln), for example, turns the tables on the slave-master relationship when the all-powerful Sultan realizes he cannot win the heart of the slave girl Zaide.

Langrée grows especially animated when he describes the leaps of musical imagination that Mozart poured into these scores. "The intermezzos in Zaide are so extreme, with lots of pauses instead of chiaroscuro. And in the entr'actes from Thamos [used by Peter Sellars to flesh out the score for Zaide] or the storm music in Idomeneo, there's almost a craziness to his use of unisono or diminished chords, his extreme contrasts of loudness, with screams from the trumpets, against sudden pianissimo. And in Idomeneo, Mozart was inspired by the opportunity of writing for the Mannheim orchestra to create some of his most challenging material. Their pride, after all, was to be able to play 'unplayable' music."

Not surprisingly, many have noticed a prophetically Beethovenian quality here - Zaide in particular, with its tale of slaves challenging tyrannical power, readily anticipates the spirit of Fidelio. "Beethoven believed very strongly that the artist had a role to elevate society," says Langrée. "I'm sure he would have loved this piece."

Yet isn't there a fundamental contradiction between the updating that Peter Sellars's brand of "director's theater" represents and the period-instrument performance values brought to the table for both of the festival's opera productions? "I feel they are exactly the same thing, in fact," says Langrée. "We've become so used to the ideal of a beautifully blended sound. But what is important for Mozart - and of course later on for Beethoven - is first and foremost the dramatic truthfulness of expression. Music is not here to be 'beautiful.' The specific timbres you get with period instruments can sometimes be quite shocking. In fact it sounds more 'modern' when you play with this completely different way of thinking."

On the basis of the correspondence that has survived from the period of Idomeneo's composition, we know that Mozart was meticulously involved in the minutest details of preparing his work for the stage, with a laser focus on creating a powerful dramatic experience. Even those with reservations about Sellars's particular interpretations must admire the collaborative intensity he brings to his projects.

Usually," Langrée observes, "there's a clear division of labor: the conductor takes care of what you hear and the stage director is concerned with what you see. Peter is the only director I know who comes to rehearsals knowing the score inside out - not just the melody and harmony, but the inside line, what the viola or second bassoon will play in a certain moment. He gently forces you as a conductor - by inspiring and suggesting - to make the theater audible as well as visible."

Both Zaide and Idomeneo present visions of an enlightened society that can overcome the fear and fatalism that hold us back, and in which human choices make a difference. Above all,
Mozart finds a musical language to convey what is at stake - now
as much as it ever was. "It is not Mozart's function to soothe," Anthony Burgess once wrote. "He reminds us of human possibilities. He presents the whole compass of life and intimates that noble visions exist only because they can be realized."

Thomas May writes about the arts. His books include Decoding Wagner
and The John Adams Reader.