THE image of a Boeing 767 slicing into one tower of the World Trade Center in New York on a beautiful fall day caused horror. The image of the second 767 slicing into the second tower clarified matters.
It was an attack, not an accident. Then the plane went down in Pennsylvania and the 747 smashed into the Pentagon.
The scope of the intent became clear. These were kamikaze attacks, scaled up to cause as much damage to American economic and military power as possible.
The images from New York were so horrific - they seemed designed to inflict a psychological wound - that the mind has a tendency to repress them.
We should never allow that to happen.
It was the beginning of a tumultuous decade. The images piled up thick and fast: Afghan men silhouetted on a ridge, watching an avenging B-52 against a clear blue sky, American Special Forces, some from West Virginia, on horseback, riding with Afghan fighters. Afghan women, graceful in their flowing blue garb.
These sights were as new to American eyes as those of 9/11.
Then came the slow, clanking invasion of Iraq. News that some Americans had been killed and were missing because a column took a wrong turn. Grainy nighttime video of the retrieval of Jessica Lynch from a hospital in Iraq.
New shocks: In the name of America, some U.S. troops committed and videotaped their abuses at the prison at Abu Ghraib. In the name of Islam, Islamists videotaped beheadings, of Daniel Pearl in Afghanistan and of many others in Islam.
Innovations: the use of a children's toy, Silly String, to detect laser triggers for bombs inside buildings, the rapid deployment of drones to collect intelligence or deliver payloads, the deployment of robots to counter IEDs.
Car bombs. Blood in the streets.
Terrible military casualties, terrible civilian casualties, and families in every country that will never heal from them.
But later, another set of arresting images, seen worldwide.
Iraqis so eager to vote that they braved threats and violence to exercise that right. One memorable shot captured a long line of black-clad Iraqi women, all patiently waiting to cast ballots.
And later, a turn of events many Americans did not expect.
Car bombings and beheadings seemed to pall on the populations they were supposed to impress. The allure of savagery began to fade.
It seems from the outside that the overwhelmingly young populations of the Arab world began to turn their eyes from al Qaida's "far enemy" - America, the tyrants' target for blame - to targets closer to home.
At the "near enemy," the repressive and often corrupt regimes that have allied themselves with Islamists to hang onto legitimacy.
Technology intruded, too.