The most frightening aspect of the present war is how easily our pre-modern enemies from the Middle East have brought a stunned postmodern world back into the Dark Ages.

Students of history are sickened when they read of the long-ago, gruesome practice of beheading. How brutal were those societies that chopped off the heads of Cicero, Sir Thomas More and Marie Antoinette. And how lucky we thought we were to have evolved from such elemental barbarity.

Twenty-four hundred years ago, Socrates was executed for unpopular speech. The 18th-century European Enlightenment gave people freedom to express views formerly censored by clerics and the state. Just imagine what life was like once upon a time when no one could write music, compose fiction or paint without court or church approval?

Over 400 years before the birth of Christ, ancient Greek literary characters, from Lysistrata to Antigone, reflected the struggle for sexual equality. The subsequent notion that women could vote, divorce, dress or marry as they pleased was a millennia-long struggle.

It is almost surreal now to read about the elemental hatred of Jews in the Spanish Inquisition, 19th-century Russian pogroms or the Holocaust. Yet here we are revisiting the old horrors of the savage past.

Beheading? As we saw with Nick Berg and Daniel Pearl, our Neanderthal enemies in the Middle East have resurrected that ancient barbarity — and married it with 21st-century technology to beam the resulting gore instantaneously onto our computer screens. Xerxes and Attila, who stuck their victims' heads on poles for public display, would've been thrilled by such a gruesome show.

Who would have thought centuries after the Enlightenment that Europeans — in fear of radical Islamists — would be afraid to write a novel, put on an opera, draw a cartoon, film a documentary or have their pope discuss comparative theology?

The astonishing fact is not just that millions of women worldwide in 2006 are still veiled from head to toe, trapped in arranged marriages, subject to polygamy, honor killings and forced circumcision, or are without the right to vote or appear alone in public.

What is more baffling is that in the West, liberal Europeans are often wary of protecting female citizens from the excesses of Sharia law — sometimes even fearful of asking women to unveil their faces for purposes of simple identification and official conversation.

Who these days is shocked that Israel is hated by Arab nations and threatened with annihilation by radical Iran? Instead, the surprise is that even in places like Paris or Seattle, Jews are singled out and killed for the apparent crime of being Jewish.

Since Sept. 11, the West has fought enemies who are determined to bring back the nightmarish world that we thought was long past. And there are lessons Westerners can learn from radical Islamists' ghastly efforts.

First, the Western liberal tradition is fragile and can still disappear. Just because we have sophisticated cell phones, CAT scanners and jets does not ensure that we are permanently civilized or safe. Technology used by the civilized for positive purposes can easily be manipulated by barbarians for destruction.

Second, the Enlightenment is not always lost on the battlefield. It can be surrendered through either fear or indifference as well. Westerners fearful of terrorist reprisals themselves shut down a production of a Mozart opera in Berlin deemed offensive to Muslims.

Few came to the aid of Salman Rushdie or Dutch filmmaker Theo van Gogh when their unpopular expression earned death threats from Islamists. Van Gogh, of course, was ultimately killed.

The Goths and Vandals did not sack Rome solely through the power of their hordes; they also relied on the paralysis of Roman elites who no longer knew what it was to be Roman — much less whether it was any better than the alternative.

Third, civilization is forfeited with a whimper, not a bang. Insidiously, we have allowed radical Islamists to redefine the primordial into the not-so-bad. Perhaps women in head-to-toe burqas in Europe prefer them? Maybe that crass German opera was just too over the top after all? Aren't both parties equally to blame in the Palestinian, Iraqi and Afghan wars?

To grasp the flavor of our own Civil War, impersonators now don period dress and reconstruct the battles of Shiloh or Gettysburg. But we need no so such historical re-enactment of the Dark Ages. You see, they are back with us — live almost daily from the Middle East.

Victor Davis Hanson is a classicist and historian at the Hoover Institution at Stanford University. Reach him at author @victorhanson.com.