When Edward Gibbon was writing about the fall of the Roman Empire in the late 18th century, he could argue that transportation hadn't changed since ancient times. An imperial messenger on the Roman roads could get from Rome to London even faster in A.D. 100 than in 1750. But by 1850, and even more obviously today, all of that has changed.

Unlike some, I don't claim to hold the mystic key to the future. But judging from past events, it seems to me that those who want to prophesy the imminent end of America's unique global role have a harder case to make than those who think we will limp on for a while, making a mess of things as usual.

It is a kind of ego booster, the way Egypt's winning the 1973 war, in the first stages, was an uplift. But I did not find when I spoke to people that the war in Iraq was seen as the major issue in American-Arab relations.

Carter's hopes died when the Soviet Union invaded Afghanistan and he ended up having to reverse policy and launch the military buildup that Reagan continued. Mr. Obama would be forced back into a war on terror if terrorist groups pull off enough damaging or frightening attacks to force this issue to the fore.