What do you feel, working in the back of the ambulance, when the front right tire blows at 65 mph on the Beltway? Someone yells "Hang on!" from the front seat and you see smoke billowing through the back window as everything starts shaking loose. Strangely, no fear. Just: This will come out one of two ways. I will take flight or I'll stay in this seat, and I know exactly how each of those will feel.

I wonder, later, why there wasn't any fear in that moment. A day later it occurs to me that I might be dead. How can I be sure?