Another perfect day, not a cloud in the September sky, as if to elide time and compress 18 years into a moment.

The prow of Manhattan extends below me. The Statue of Liberty and the Verrazzano-Narrows Bridge lure my gaze over land and water to the horizon. This is what they saw before the planes hit, as powerful an image of American possibility as exists — the gateway to a new land, a place, to quote Fitzgerald, where “man must have held his breath” at the sight of a place “commensurate to his capacity for wonder.”

At this anniversary of 9/11, I found myself on the 50th floor of One World Trade Center, in the 1776-foot Freedom Tower, which rises at the site where the Twin Towers stood. “Leaping from here,” says Lu Maheda, the acting deputy assistant secretary of media operations for the Department of Homeland Security. “Think about that.”

Think about that, the choice of people caught, on a clear New York morning, in the early promise of the 21st century, between inferno and vortex. Try as you might, you cannot quite place yourself in that death trap. It is beyond our imaginations, as the attack itself was.