Last Saturday, as the people and military of Egypt shared the streets of Cairo in uneasy fraternity, the Metropolitan Opera was broadcasting Puccini's "Tosca." If by some chance you happened to be following both, listening to the Met's weekly radio broadcast while streaming al-Jazeera on the computer, there was a strange and powerful serendipity: Swift and violent events in an ancient city formed a vicious counterpoint to a swift and violent work of art, from another century, another culture, almost another world entirely.

The surfeit of modern media can create surreal juxtapositions. But when the villain of "Tosca," a murderous and lecherous tyrant named Scarpia, entered in Act 1, it felt like more than an accidental point of contact with the events in Egypt.

Scarpia is a thug, kept in power by an extensive network of secret police who use torture and informants to maintain an oppressive regime. Scarpia could only exist after Shakespeare, after the creation of villains such as Iago, who know their own evil from inside and out, who know they are evil, not just misunderstood, not just set upon by complex events and heavy burdens. Scarpia abuses power, willingly and in full knowledge that what he does is reprehensible.

When he first enters, interrupting a bumptious children's choir singing in a church, the timpani and lower brass produce a rumbling thunder of sound on the notes B-flat and E. This is the tritone, an interval so unstable and harsh that it has been known for centuries as "the devil in music." It is a horrifying moment, and by placing that most unstable interval in the lowest range of the orchestra, Puccini limns not just the man, but the fundamental instability of all tyrannies.

Whatever order may seem to exist on the surface is undermined by a far deeper and uglier perturbation of decency. Governments such as Scarpia's, Puccini argues, are contrary to nature. They must be resolved, as music always moves to resolution.

There's a tendency to think that art is complicated and nuanced, while politics is crass and direct; that the creative mind deals in degrees, while people who traffic in power prefer black and white.

But sometimes just the opposite is true. Scarpia's evil emerged across the airwaves with blunt perfection, while U.S. political leaders seemed unable to say anything that didn't sound like an equivocation or carefully parsed half-truth. Most art is, of course, more subtle than politics. Yet, when one needs moral clarity, there are some artworks that are much more satisfying than anything politics can offer.

It was anything but clarity one heard from the political class. Egypt, meaning President Hosni Mubarak, was an important ally; Egypt, meaning the people of Egypt, deserved a better, freer, less sclerotic government. The fear of instability in a strategically important country was offered up with strange echoes of the old domino theory, as if freedom was all well and good for some people, but we couldn't afford its side effects in a country so close to Israel, sitting atop one of the world's most import shipping routes. Revolution seemed to be on the streets, and suddenly, the stewards of a once-inspiring democracy could speak only of incremental reforms and baby steps to self-governance.

The horrifying, almost tactile ugliness of the noise that Scarpia makes is a form of moral distillation. It disgusts us, without nuance, and functions in the memory and the moral life rather like an allergen. Puccini's Scarpia strengthens our natural immune reaction to tyranny, to names such as Pinochet, al-Assad, Amin and Mubarak.

If art in so many other ways expands our capacity for tolerance, there are occasional moments when it does something just as powerful - refreshing our intolerance of cruelty, torture and men who use fear to keep power. Simon Legree may not be the most subtle character in American literature, but the vicious slave owner who brings Harriet Beecher Stowe's "Uncle Tom's Cabin" to the brink of bad melodrama serves a purpose. Our loathing for him makes his worldview forever abhorrent to us.

But this is not, as Milton would say, to compare great things to small. Villainy, in art, can touch the conscience, but not wound the body. What was happening in Egypt was far greater than anything that will ever happen on any stage or in any novel. By intuition, or some natural wisdom of the crowd, the people in Cairo protesting the 29 years of Mubarak's regime created images as vital and clarifying as anything that could be fabricated through the mechanism of art: a crowd kneeling in prayer in the presence of tanks; a surge of bodies against a phalanx of batons and water cannons; men and women celebrating with soldiers who, for the time being, had chosen humanity over murder. One would have to tame these images, dilute them somehow, before they could serve an artistic purpose. Reality is too dramatic.

The power of the kind of art Puccini was making isn't as a second-rate substitution for these far more intense, far more terrifying and inspiring visions. Rather, it is to remind and refresh the moral sensibility, when the mind is otherwise preoccupied with the tedium of normal life. Art keeps us raw, susceptible to the power of the kind of images that were emerging from Cairo.

Which is why it was so maddening to listen American political leaders. The administration opted for caution, for words such as transition and reform, for avoidance when it came to a clear statement that its sympathies were with the people rather than the tyrant. On the right, a campaign of vilification against Mohamed ElBaradei - courageously presuming to play the role of democratic leader - was already underway, as if he can never be forgiven for having been right about the absence of weapons of mass destruction in Iraq. Pragmatists and ideologues from across the political spectrum were in agreement, alike in their immunity to the images emerging from a land on the cusp of liberation.

There's a reason that we use the metaphor "tone-deaf" to describe a particular kind of political failure. Perhaps the most infuriating thing about the American political establishment's sudden frenzy for nuance was how contrary it runs to the fundamental American loathing of authoritarianism. Even more frustrating is the inability to reach through the television screen and say directly to a people facing great peril and immense promise that while our political leaders are tone-deaf, we are not. It's been a long time since we sang it, but we know how this song should go.