New York. The sun is shining, the snow is receding, and I am just a day or so from my fourth visit to Ground Zero, now memorialized by its haunting appearances in old movies and television shows. For all of us who either personally witnessed or found ourselves transfixed by the images of destruction, the events of that sunlit September morning remain suspended in our memories, bracketed off from the normal rhythms of time by which we mark the passage of our lives.

But while our memories can retain the poignancy of an event, the physical site of the event often is reabsorbed back into the landscape. The first time I saw Ground Zero (which was after the rubble had been removed), I was struck by how small an area it was in comparison to the size of the city blocks that surrounded it. And although there were some tourists who came to see the site, I noticed that, for many commuters on foot and in vehicles, Ground Zero was just one more place to navigate in a city that relentlessly presses you forward.

The impact of 9/11 on the nation's psyche is almost immeasurable and in retrospect, the insurance industry was not immune to its effects. It was a measure of national pride – and a need for reassurance – that drove politicians to promise New York billions to rebuild the 16-acre site. At the same time, actuaries sounded the alarms that acts of terrorism could not be predicted, modeled, or even insured. Industry experts lined up to say that the specter of terrorism had changed the rules. After decades of collecting data and studying the risk associated with hurricanes, earthquakes and tornados, insurers now faced a new, uncertain challenge.