The snake is one of the very few creatures that turns up in nearly every mythology on earth—Egypt, Greece, the Norse north, the Aztecs, India, China. Take your time with the others. The list is short.

Fear alone does not explain it. The lion and the eagle were made into gods by the people who lived beside them. The snake was made into a god even by people who almost never saw one—in the Norse north most of all.

I noticed this prevalence while writing Sweet Potato, my new novel about a young woman who handles rattlesnakes and searches for the mother she has never met. I went looking for the science of venom. I found the mythology instead, waiting in every corner of the human record.

One creature, every culture

Across cultures that never traded a word or a caravan route, the snake tends to mean the same handful of things. Death and life. Poison and cure. The keeper of secrets. The guardian at the threshold. People who had no way of knowing one another arrived at the same idea: the snake is dangerous, and the snake is sacred, and those two facts are intertwined.

What they shared was not fear alone. Anyone can fear a snake. What they shared was reverence, the sense that this low, silent creature knew something the rest of us did not.

The rod of Asclepius, and the snake that heals

Look at the side of an ambulance. You will likely see a single snake coiled around a staff. That is the rod of Asclepius, the Greek god of medicine, that has marked the healing arts for more than two thousand years. It symbolizes the ancient Greek belief that snakes know the cause of illness as well as its cure.

People often draw the caduceus instead, two snakes and a pair of wings, but that one belonged to Hermes, god of merchants and thieves. In the US the caduceus of Hermes and the Rod of Asclepius are often confused, and the caduceus sometimes mistakenly appears in medical settings.

Why a snake for medicine at all? Because a snake sheds its skin and appears to be reborn, which is equated with a belief in eternity or rejuvenation. Because its venom, in the right hands, was already a medicine.

The creature that could kill you—if it was venomous—was the one you prayed to for a cure. I keep coming back to that idea. It sits at the center of my book.

Several years ago I visited the Temple of Asclepius and the ancient amphitheater at Epidaurus.

Jormungandr, the Norse world-serpent

Far to the north, the Norse imagined a serpent so vast it circled the entire world beneath the sea, holding its own tail in its mouth. They called it Jormungandr or, in Icelandic, Miðgarðsormur. It was a child of Loki and the great enemy of Thor. When it finally released its tail, the world would end. Today that frightening serpent is often seen on muscular biceps as tattoos.

A snake large enough to bind the world together, and to unmake it. Even its shape carried meaning. The serpent swallowing its own tail entered the Western tradition through ancient Egyptian iconography and Greek magical tradition. The Greek term for this symbol for eternal cyclic renewal, a cycle of life, death, and rebirth, is ouroboros. It is the thing that has no beginning and no end. Look for that icon in bracelets and necklaces.

Quetzalcoatl, the feathered serpent

In the valley of Mexico, the snake grew wings. Quetzalcoatl, the feathered serpent, was among the most important gods of the Aztec world and the cultures that came before it. He was the wind and the morning star, the bringer of knowledge and of maize, a maker of humankind.

A serpent that belongs to the earth and also to the sky. That is the whole trick of the snake, made visible. It lives in the dirt and it touches the heavens.

The nagas, guardians of wisdom

In Hinduism, Buddhism, and Jainism, the naga—semi-divine water spirits, who are half human and half cobra—guard springs, rivers, and underground treasures. They are protectors. The god Vishnu sleeps on the coils of a great serpent between the unmaking of one world and the making of the next. To meet a naga is to stand near hidden knowledge, if you are worthy of it.

Here the snake is neither villain nor victim. It is the keeper of what matters, coiled around the treasure so that only the deserving may pass. I find this repeated duality that surrounds snakes endlessly fascinating.

Why the snake, and not something else

So why this animal? Why not the wolf, the bear, the great birds?

Because the snake does the one thing we most want to do and cannot. It sheds its skin and starts again. It grows old and steps out of its old self, whole and new. To people who watched their own bodies age and fail, this was not a small thing. It was a promise.

And the snake lives between worlds. It moves below ground and above it, through water,  across stone, and up trees. It has no legs and yet it travels. Its eyes never close. It carries death in its mouth and, we would eventually learn, medicine in the same place. The snake is the creature that refuses to stay on one side of any line. That is why it turns up everywhere. It is the shape our oldest questions take.

How the snake found its way into Sweet Potato

My character Lorenza grew up with all of this, though she did not know it at first. Her adoptive mother, a frustrated artist, kept art books full of serpents: a soothsayer strangled by sea snakes, Medusa with her living hair, a smiling snake in the Garden of Eden. Lorenza turned those pages as a child and believed she alone had discovered how much power a snake could hold.

She believed in that power the way you believe in a talisman. When she began extracting venom for a living, she had a white snake tattooed above her heart, a creature from a fairy tale she had loved since she was small. It was an act of faith.

Then she met the science. Real venom, real research, real medicine drawn from the thing the world runs from. By the end of the novel she believes in a different kind of power. The tattoo stays the same. What it means to her changes completely.

That is the arc I wanted. A young woman who inherits an ancient story about snakes and, without quite noticing, trades it for a truer one. The mythology was never wrong, exactly. It was the first draft of something we are only now proving in a laboratory. What can kill you can also heal you. Every culture on earth knew it before we did

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