Some time ago, a friend of mine was hit by a bus in New York, one of almost 5,000 pedestrians killed in traffic every year. I also lost a nephew to gun violence — one of more than 11,000 Americans slain by firearms in this country. And I fell out of a tree that I was trying to prune in my backyard. I was O.K. But the guy next to me in the trauma ward was paralyzed from his fall. He was taking down his Christmas lights.

So it goes. Life is full of risk. Every day brings a minor calculation with the possibility of mortality: cross the street on red, get on a plane, jog in the heat.

It was encouraging, then, to watch the congressional debate this week over the Patriot Act, and realize that we are learning how to be afraid. At least, we’re starting to put the infinitesimal risk of being killed by a terrorist in perspective.

Though a majority of Americans are still worried about an imminent terrorist attack in this country, the number of people who think such an assault will happen in their home area has dropped to the lowest figure in the post-9/11 period — 16 percent.