But among the artifacts that will never be found—among the objects that will disintegrate long before anyone from elsewhere arrives—is a certain patch of sidewalk on a California street where once, on a dark afternoon in summer at the waning end of the year of the slowing, two kids knelt down together on the cold ground. We dipped our fingers in the wet cement, and we wrote the truest, simplest things we knew—our names, the date, and these words: We were here.
