Why does Vivian’s house have a false alarm?

The autumn our daughter Carly was two and a half, we admired the fallen leaves together. “But, Mommy,” she asked, looking up at bare branches, “how do the leaves get back on the trees?”

Our old house in New Jersey had a smoke alarm in every room. The one in our son Matt’s bedroom was directly over his crib. He loved that smoke alarm. A little red light on it blinked once a minute to show the alarm was operational. As an infant, Matt lay on his back, watching for the red light, gleefully waving his arms and legs every time it blinked.

In our old neighborhood, people invited trick-or-treating families into their homes on Halloween. Most children headed straight for the treat bowl. Two-year-old Matt walked right past it, located the home’s interior hallway, and checked for a smoke alarm. Then…