Of the three operas Mozart wrote with librettist Lorenzo Da Ponte — Le nozze di Figaro, Don Giovanni, and CosÐ fan tutte — CosÐ is one most riddled with paradoxes. It is both the least splashy and the most overt; the most immediate and the most universal; and ultimately, the least understood. It finds both Mozart and Da Ponte at their most human, their most unmasked; yet it is all about being masked, and using these masks to tell the truth.

This is not to say that CosÐ is not popular. After falling into disfavor with the idealistic Romantics of the 19th century, it made a big comeback during the 20th, becoming a cornerstone of the operatic repertoire. As such, it has frequently served as a vehicle for updating and radical reinterpretation, most famously by Peter Sellars, who transferred the action from Da Ponte's rather arbitrary Naples to a 1980s American diner — Despina's-by-the-Sea — recasting Don Alfonso as a Vietnam veteran. The impact of CosÐ has also spilled over into other art forms: a film has been made about lunatics staging the opera in an madhouse; and it has figured in films including John Schlesinger's Sunday, Bloody Sunday and, especially, Mike Nichols' Closer, not only in the plot (which centers around the question of fidelity) but in the soundtrack as well. There is even a popular sandwich chain named after it. Though it may lack the sex-farce frisson of Nozze or the fire-and-brimstone of Don Giovanni, something about CosÐ continues to speak to the contemporary soul.

Maybe that's because CosÐ raises so many questions, and answers very few of them. Its frank talk of love, fidelity, and the nature of men and women poses questions that are, in the most literal sense of the word, existential. Are "they" (the feminine "tutte" of the only vaguely translatable title) really "like that" ("cosÐ")? Is there even a "they" that we can speak of? Does womankind — or any group of people — really have such a classifiable essence? In 2006, with several hundred years of "enlightened" thinking between CosÐ and us, is this still a worthwhile question? It is these complex questions, and many more, that the scientific Don Alfonso seeks to answer, Age of Enlightenment-style: with an experiment performed on two pair of naÇve, hapless "lab rats."

Can a lover — or, more specifically, can our lover — be true to his/her word? Many operas have dealt with this seemingly simple question — The Rape of Lucretia, Wozzeck, A Midsummer Night's Dream, An American Tragedy, Madama Butterfly, Der Rosenkavalier, Le nozze di Figaro, The Rake's Progress, Otello, and La traviata immediately spring to mind. But CosÐ, with its fleet pacing, whimsical touches, and jarringly joyful finale, somehow seems more akin to our so-called "romantic comedies," films like When Harry Met Sally, Unfaithfully Yours, the bulk of Woody Allen's canon, and even the bitter-scented We Don't Live Here Anymore or Closer. We as a culture most often seek to understand ourselves at the movies, as, in 1790, people did at the opera.

Throughout the entirety of CosÐ, war is in the air, as was the case in Vienna circa 1790. Ferrando and Guglielmo are soldiers, bumbling dupes who use their occupation to manipulate their lovers. After accepting Don Alfonso's wager on their fianc_es' fidelity, they scare the sisters Fiordiligi and Dorabella into believing that they have been sent off to war to die. They do this at the urging of Don Alfonso (our Iago, or agent provocateur), but are abetted by the sisters' maid, Despina (an apparatchik and aide-de-camp who will do anything for a laugh and a buck). All four conspirators go to extreme lengths in their charade, staging a tearful farewell, impersonating exotic strangers, feigning suicide by poisoning, dressing in drag as a doctor and a notary, etc. In the 24 hours during which Don Alfonso, according to the terms of the wager, has Ferrando and Guglielmo under his complete command, he is determined — at all costs — to win the day and to prove his point.

Are they all as stupid as they seem, falling quickly and easily for the Don's obvious ploys and all the flimsy disguises, believing every word he says, and entering into a bet that nobody can possibly win? Love makes fools of us all, or so it would seem. "Poor little ones," the Don laments of his feckless officers, "to wager 100 zecchini on a woman!" In his cynical mind, they are worth a good deal less.

Today, the conventions of this opera are laughable and require supersized suspension of disbelief. Are we truly to believe that Dorabella and Fiordiligi are dumb enough not to recognize their own lovers simply because they've dressed up as "Albanians" and arrived mustachioed? This is the most ridiculous of conceits — yet no more so than all the masked wooing and drag-dressing that happens in most of Shakespeare's comedies. Then again, are we truly to believe that the citizens of Metropolis do not recognize Clark Kent as Superman because he sports eyeglasses? Did nobody in Gotham see the similarity between the lips of Bruce Wayne and Batman? We know full well that both the mixed-up lovers of CosÐ and these fictional heroes never existed, yet through their sheer funniness (it is no accident they are called "comic books"), they sketch out the vagaries of the human spirit. We obviously do not buy into these stories as realistic depictions of life, but rather as life writ large, absurdly drawn and therefore one step removed from our own experience. But this is the magic of the theater or of any work of "fiction": through the impossible-to-believe failings of our onstage lovers (or the super-heroics of our comic book idols) we come to recognize and square ourselves. "If you want to tell people the truth," Oscar Wilde quipped, "make them laugh, otherwise they'll kill you." This is a lesson Mozart and Da Ponte heeded well, long before those words were written.

Apart from its unsentimental portrait of the human condition, what brings us back to CosÐ again and again is its music. We may be a little baffled by the labyrinthine story (though it is nothing compared to Le nozze di Figaro in terms of sheer plottiness!), but who can forget the cascading pastoral clarinets when first we meet Dorabella and Fiordiligi — a motif that reappears again and again throughout the score, rekindling in our hearts this delicate moment. Despina's spirited "Go ahead and cheat if you like" waltz in Act II; the buildup of moving duets in the second act which culminate, ultimately, in the classic Mozart "forgiveness" duet; and the fact that throughout the opera, the most heartfelt and aching melodic sentiments are delivered by and to people in disguise — a Mozart-Da Ponte signature specialty. The score paints in vivid Technicolor the heartbreak and comedy of this tale, helping us sort out who we are. The music hits us where we live.

Daniel Felsenfeld is a New York-based composer, author, essayist, and journalist.