In our home, the stairs to the second floor rise on one wall of my son's bedroom, and the hall to my bedroom follows another. So especially when he's near the beginning or end of his slumber, I try to walk lightly.

When I was young (though much older than he is now), I had a different reason to step quietly on stairs at night: Typically, I was en route to or from an illicit trip to the kitchen, seeking to eat in secret what I knew I'd be faulted for if my parents knew.

I've witnessed the passages of life in which caregivers become the cared-for, and perhaps this is a corrollary, or a part, of that process. Still, when I'm trying choose the part of the tread that squeaks least, I can't help but remember that other time.