My wife, who reads more than I do, mostly books I'd never open, says the ground is always moving beneath our feet. Not an earthquake, she tells me, but plates that shift below the continents and the oceans. There's even a hum, she says, when I turn away before she's finished.

"A hum nobody can hear, right?" I say, expecting that to end things, but she doesn't let it go.

"It's audible for some," she says. "A low murmur that keeps a few of us awake."

"You, too?" I say, though she doesn't seem to hear.

"There's a woman who says that hum is like torture. Since she started hearing it, she gets headaches, nosebleeds, and insomnia."

"Not you?" I try, but she isn't listening.

"Somebody's recorded it. He says it sounds like what a fetus hears in the womb."

We have no children, so I get what she's working toward, letting science criticize me for our empty house. I wait for it, her going bitter, but she says, "I have a story for you, one I just read this morning, but you have to come outside with me and go for a walk into the desert. Not far, just out there a hundred yards or so, far enough so we're alone."

"It's supposed to rain for once," I say. "We'll get soaked."

"Just say you'll walk," she says, and I fall in beside her.

Out there, every spot looks nearly the same, but she settles on a place between two young saguaros and begins. "Spadefoot toads use their back legs to burrow backwards when this earth gets too dry," she says. "They go deep enough to be cool, farther than you think."

"So, they're all way down there now?" I say.

"Yes," she says. "Maybe ten feet. Maybe waiting, half-sleeping for weeks or months until they hear the sound of raindrops on the surface. They need to hear rain before they claw their way back up."

She holds out her hands just as I feel the first drops. "You think they're coming up tonight?" I say, and she looks skyward as if she's wishing down a storm.

"Sometimes it takes years for a downpour," she says. "Then one night there's enough rain to prompt the toads to surface where they sing and are sung to and mate."

I look up, too, the rain pelting down now, and she takes my hand. "They synchronize their song," she says. "They bunch together because owls look for single targets, and this keeps them safe."

"The owls think the earth is singing," I say.

"Yes," she says. "Yes," and she lays my hand on her belly, nods, and we begin to sing.

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