Here’s a secret about movement: speed cares only about distance, but velocity is aware of direction.

Here’s another secret about movement: every living creature on this planet is moving fast. But the body tricks us into not noticing the planet’s movement.

Constancy is the first law of motion. Its other name is inertia, which is not to say not moving so much as not noticing. It can substitute for trust.

Earth takes a predictable year to get back to the same place. Orbit is one name for the path. Here we go again. Or still. At 67,000 miles an hour.

Vertigo can look like inebriation. It can look like possession. It often looks like nothing at all to someone else. It’s a problem with trust.

Because the ears care where the head is going, the human body senses a change in velocity even when the eyes lie.

Vertigo can make one think air has stopped moving. Sometimes, the circle of vignette closes in or tilting begins. Often, I walk as if through a wake I’ve created by moving.

Here’s another secret: the days are getting longer. This fact seems to be about time, but it is about movement, about a seemingly imperceptible change in the speed of Earth’s rotation.

I can use a specific series of timed head repositionings to tell my inner ear, Let me show you how you are wrong.

To spin yarn is to spin in the transitive, as fingers transfer movement to something other than fingers. The fingers remain as they are, and the shorn coat of an animal becomes something else.

Twist is what’s done to make yarn; twist is also the yarn itself.

Vertigo is the intransitive form of spin. There’s nothing to give spin to.

In her poem “A Good Story,” Ada Limón wrote, “Today, my head is packed with cockroaches, / dizziness and everywhere it hurts.” Five years before I read this poem, Ada Limón came here to read her poems aloud where I teach. She told me then that she had bouts of vertigo. It would take me another year to understand, but she had given me permission.

Yarn can be wound onto a spindle for the future. A yarn is also a story.

Then, the classroom listed like a ship I was captaining, and the students swayed like rowers.

Then, vertigo slipped my tongue with distraction at a faculty happy hour. It is a terrible thing, this lack of focus. But not as terrible as the wrong word in a conversation with people who trust words, who judge words.

Name a city that begins with A and then B and so on: Albany, Boston, Cincinnati. I know why these city names come to mind even though I know other cities better. These names are attached to one-time memories. Answering quickly is necessary for the test to work, the audiologist tells me. This task of naming seems easy. This test is not as terrible as I expected.

Dorianne Laux has a poem called “What’s Terrible” that begins with an epigraph from Ursula K. Le Guin: “It is terrible, but not very terrible.” Terrible thing, this disorientation of vertigo.

Dorianne Laux also has a poem about the moon; it’s factual. The moon is moving away from Earth, seven feet in my lifetime. I can measure that distance. I don’t know what to do with this fact of the moon’s unnoticed leaving. Is it terrible?

Start at the beginning of the alphabet. This time, name animals: I know a bird that begins with the letter A. It’s an unusual word, not an everyday bird. My delay in response demands the audiologist’s prompt. Not crocodile, but—. Of course. Alligator, I reply. But that is not what I was thinking and couldn’t say.

A slip of the tongue seems to me less terrible than a loss for words, less terrible than searching and finding nothing in the place the bird is supposed to be.

Thinking is an intractable scheduling problem, which is to say that there exists no optimal way for the brain to complete all the desired tasks in the time expected.

Thrashing describes what happens when a computer’s memory cannot store and retrieve fast enough to do all the tasks it’s been asked to complete. The computer’s performance deteriorates. It gets stuck in interruptions.

There’s redundancy built into the body’s system for orienting itself in the world. I’m supposed to trust my eyes, ears, and feet all at once. They are supposed to cover for each other if one gets interrupted. My eyes, ears, and feet are supposed to agree. Vertigo results from contradiction.

The word dizzy comes from the Old English meaning foolish. What’s a person supposed to do with the terrible foolishness of an ear’s mistake?

Thinking in contradictions is a kind of thrashing. It can look like panic or paralysis. It is movement that feels like stillness unless you’re in it.

Imagine Karl Wallenda and his seven-person chair pyramid on a tightrope. Hold your breath. Imagine the eight-person pyramid. Imagine a walk in the park a hundred feet in the air, and this is the day Karl falls to his death because his feet didn’t follow each other on the rope. Imagine Nik Wallenda, Karl’s great-grandson, walking between towers. I know these towers and the ground between, but not that stretch of rope sixty stories up, not that stretch of air. It is cold and windy. He is blindfolded. There is no safety harness, no safety net.

The brain’s plasticity is the power to change when nerves go awry. The physical therapist tells me I can be made less dizzy by the world if my brain can be taught to think about movement differently, if I can pay more attention to my feet. I can learn not to trust my ears.

What does it mean to believe I can be less terrible, to think an impeccable version of me can be created? Esmé Weijun Wang writes of “an impeccable self without disorder” that someone may try very hard to get or get back. But she says, “There may be no impeccable self to reach.” If the history of the word impeccable suggests one is unlikely to falter, to fail, to sin, then there are many ways I’ve already failed and many sins I may commit again.

Earth is a body that orbits the sun, and it is also a body that spins a thousand miles an hour. “The body / is so body,” Ada Limón writes of the human body in the poem “A Good Story.” Earth is so body too, so full of cockroaches, dizziness, and hurt.

Earth’s third kind of motion is called precession, which is part of what explains the motion of stars in the night sky. Polaris has not always been Earth’s North Star. Two thousand years from now, there’s a new North Star coming, not because the stars move but because our planet wobbles.

What’s a space supposed to do with a body? What’s a body to do with space?

Vertigo is my ear’s understanding of precession. My ear tells my brain something not worth noticing. This self-declaration that I can understand one thing in terms of another is one way to deal with the inscrutable.

Here’s a secret: a spinning object moves faster at its widest than it does at its narrowest. Hold out your arms, and imagine the circle your fingers travel through the air as you spin like a planet. Your hands trace an equator’s path, and your head and feet are the north and south poles. Your feet barely move; you’re going nowhere. Your fingers know a different distance.

Experience is a frame of reference that fools us. We pretend our ears are just for hearing.

Twisting yarns together is called plying. To ply can mean to provide or to besiege, almost opposites of each other but not quite. To ply can also mean to travel, which is to suggest that one knows where one’s going.

If it weren’t for inertia, Earth’s three motions might be enough reason for vertigo. Inertia is supposed to let our bodies choose which movement to trust.

As I drive home from the audiologist, I think, albatross. A large seabird that glides on the wind rising from waves, that dives into water and returns to the air. A bird that hardly flaps its wings to travel hundreds of miles. A bird that always knows where it is. The bird one wears around one’s neck as punishment.

Ada Limón has a poem called “Calling Things What They Are.” In it, she writes, “To think there was a time when I thought birds were kind of boring.” I used to hardly pay attention to birds. But these past few years, my mind keeps returning to them, and like Limón, “I like to call things as they are.” Albatross, albatross, what a word, what a bird.

I move as if there must be a safety net to catch me.

ANNA LEAHY’s latest books are the poetry collections Gloss, What Happened Was:, and Aperture, as well as the nonfiction book Tumor. Her work has appeared at Aeon, Atlanta Review, The Atlantic, Bennington Review, BuzzFeed, Poetry, Scientific American, The Southern Review, and elsewhere, and her essays have won top awards from Mississippi Review, The Los Angeles Review, Ninth Letter, and Dogwood. She edits the international Tab Journal and has been a fellow at MacDowell and the American Library in Paris. Find her on Twitter at @AMLeahy.