There's a certain slant of light, On winter afternoons, That oppresses, like the weight Of cathedral tunes.

November 22nd. In the middle of the car wreck or the plunge down the mountainside, or in the mind of the drowning, time slows, then stops-the way it does for some Americans every year when the page of the calendar is torn away and today's date revealed: November 22nd.

It is always 12:29 Dallas time when the motorcade comes into sight. Nothing ever changes in the immutable past, no matter how much we want it to.

Emily Dickinson's certain slant of light is captured forever in the Zapruder film we can't stop watching:

Click. The presidential limousine coming down Houston makes a sharp left onto Elm.

Click. The president is smiling, waving.

Click. Mrs. Kennedy looks at him with concern.

Click. A bystander jerks his head suddenly toward Dealey Plaza.

Click. The limousine is lost behind a street sign.

Click. The president reaches for his throat, slumps toward his wife.

Click. The governor of Texas, seated in front of the president, falls forward.

Click. The shattering impact.

Click. Mrs. Kennedy rises.

Click. She is pushed back into the car by a Secret Service agent.

Click. The limousine disappears from view beneath an underpass, headed for Parkland Hospital and history.

The film runs 15 seconds. And an eternity.

None of us will forget where we were when we heard. I was on the subway heading for a job interview in Manhattan. A dirty, disheveled man came down the aisle-nothing unusual in a New York subway-but he leaned over and whispered something in my ear, and then moved on to whisper it to the next passenger, and the next, and the next. It took me a while to make any meaning of the slurred words, and then absorb them: Continued...