Washington has peculiar customs. Every year, the American Enterprise Institute invites hundreds of guests from the chattering class to a feast, typically on tenderloin of beef with wild mushroom ragout, but nobody gets to eat until they've listened to a one-hour lecture by the guest of honor. The other guests often fidget and squirm, devouring the bread, butter and wine put on the table to mollify the multitude.

But not this year. There was red meat in the lecture to go with the strong drink on the table, and when Bernard Lewis, the eminent British historian, offered to cut his speech short when he ran over his allotted time, the audience begged for more. Not many audiences in Washington (or anywhere else) will sit still for overlong scholarly lectures on an empty stomach.

Bernard Lewis, age 90, has studied Islam and the Middle East for more than half a century. The Capital grapevine has it that he strongly influenced President Bush to take the coalition of the willing into Iraq. His books have been important to historians, but he wasn't known to most of the rest of us until after 9/11, when the West woke up to its ignorance of the Middle East and Islam, beyond the fanciful tales of the caliphs, harems and camel drivers of the Arabian nights.

Crucial reading soon included his book, "What Went Wrong," in which Mr. Lewis dissects the sociology and psychology of the Muslim world after the fall of the Ottoman Empire, when Muslim humiliation became total. But instead of examining their own responsibilities for their failures, the Middle Eastern governments looked for others to blame for their demoted status. "Who did this to us?" they asked. Blame was variously assigned to the Mongols, the Turks, then the French and the British, and now Israel and America. The Muslims refused to see the source of their weakness, beginning with the brutal mistreatment of women.

"The status of women, though probably the most profound single difference between the two civilizations, attracted far less attention than such matters as guns, factories and parliaments," says Mr. Lewis. Half of the Muslims are forbidden to contribute their creativity to the Islamic civilization.

To understand the Middle East's great antipathy to America, however, he looks to other changes in the modern world. During the Cold War, Arabs and other Muslims learned to manipulate and profit from Western rivalries. When the era of outside domination ended, older, deeper trends in their history, which had been submerged, returned with a vengeance. These include ethnic, religious and regional differences, the particularly destructive internal rivalries.

Mr. Lewis is a meticulous historian who offers specific details for analysis, not predictions. But he sounds alarms when he describes differences in perception, East and West. When the Soviet Union was defeated in Afghanistan, we read it as a victory for the West; Osama bin Laden saw it as a defeat of the more dangerous of the two superpowers. When the United States did not respond to terrorist attacks on its embassies, on the USS Cole and the first attempt to bring down the World Trade Center, he concluded that America was weak and unable to reply to its enemies. The cosmic struggle could easily be taken into the heart of the remaining superpower.

He draws chilling differences between "them" and "us." The Muslims bring fervor and conviction to the struggle; we don't. The Muslims are self-assured in the rightness of their cause; we answer with self-denigration and self-debasement. Muslims prize loyalty and discipline; we prize politically correct multiculturalism. Most troublesome of all, he says, demographics favor the Muslims. He worries whether there will be an "Islamicized Europe" or a "Europeanized Islam." The assets of the West are freedom and the unfettered pursuit of knowledge, and he offers the hope that Muslims will eventually find these things appealing. But he concedes it's only hope.

After he finished his speech, Eric Felten's Orchestra treated the crowd to dancing to music from the World War II era, the swinging sound of Glenn Miller, Tommy Dorsey and Harry James. The music drew the obvious contrast between then and now. The attack from the skies on September 11 has been frequently likened to December 7 at Pearl Harbor, when the Japanese calculated America was weak, too. The Germans and the Japanese soon learned otherwise. "What is needed [today]," says Bernard Lewis, "is clarity in recognizing issues and alignments, firmness and determination in defining and applying policy." But is anyone listening?