Only children keep their eyes open. The only thing they have got is sense; they have highly developed “input systems,” admitting all data indiscriminately. Matt Spireng has collected thousands of arrowheads and spearheads; he says that if you really want to find arrowheads, you must walk with a child—a child will pick up everything. All my adult life I have wished to see the cemented case of a caddisfly larva. It took Sally Moore, the young daughter of friends, to find one on the pebbled bottom of a shallow stream on whose bank we sat side by side. “What’s this?“ she asked. That, I wanted to say as I recognized the prize she held, is a memento mori for people who read too much.