I'm not sure how long ago it was, that summer afternoon at our friends' house when a neighbor drove her car dramatically into the yard and got out to say, catching her breath with every few words, that her two little boys were missing and that she feared they had wandered into the woods.

This sounds like the start of a suspenseful anecdote, but in fact, there is little to match the excitement of the start. My friend and I ran up the lane to the neighbor's house and then fanned out among the trees. We probably searched for no more than half an hour. Meanwhile the two boys and their dog meandered back home. Mom thanked us profusely; we were glad to be of help. Back to the barbecue.

What makes this incident so memorable for me is the sensation of supernatural lightness that I felt running through the woods. The terrain was rough, the temperature hot enough to discourage running, and I was not in especially good shape. Still, I can remember bounding deeper and deeper into the woods with an overwhelming rush of exuberance.