What One Papal Bull Reveals About Where Our Superstitions Actually Come From

You knock on wood without thinking about it. You toss salt over your shoulder if you spill it, or you know someone who does. You’ve watched a friend refuse to walk under a ladder, not because they believe in curses exactly, but because, why take the chance. None of this feels like belief. It feels like habit. That’s what makes superstition strange to look at directly. It doesn’t announce itself as faith. It just sits in the muscle memory of a culture, passed down so quietly that most of us never ask where it came from. A superstition is a small leftover of what a community once believed about fate, sin, protection, and the line between the visible world and whatever sits behind it.

I’ve written before about why people who swear they don’t believe in any of this keep doing it anyway, in a piece called The Small Habit You Won’t Admit Matters: Why People Who Don’t Believe in Superstitions Still Follow Them. The short version is that the habit costs nothing to keep and just enough to drop, so the mind holds onto it long after the belief is gone. What that piece didn’t get into is where the habits themselves came from. That’s the part we’re going to discuss here.

That doesn’t make these beliefs primitive leftovers, something we’ve simply failed to outgrow. They carry real cultural weight. Trace one back far enough and you’re usually looking at church doctrine, folk religion, or a fear so old nobody remembers where it started. Often, you’re looking at all three tangled together.

Wood, Salt, and the Space Between the Living and the Dead

Take knocking on wood. The story most people repeat traces it to the Celts, who believed spirits, sometimes called dryads, lived inside trees, particularly oak, ash, and hazel. Knocking on the trunk was thought to wake up the spirit and call on its protection, or to thank it for good fortune already given. It’s a good story, and it fits neatly with what’s known about ancient tree worship across Europe.

It’s also probably not where the phrase comes from. The earliest written record of “touch wood” as a superstitious phrase only dates back to 1898, with “knock on wood” following close behind in the early twentieth century. Folklore researcher Steve Roud has argued the real root is a children’s tag game called “Tiggy Touchwood,” in which a player was safe from being caught as long as they were touching wood. If that’s true, our modern habit descends less from pre-Christian tree worship and more from a Victorian playground rule that outlived its own game. There’s over a thousand years of silence between the Celts and the first written mention, which is a long time for a belief to survive with nobody bothering to write it down.

Throwing spilled salt over the left shoulder carries a cleaner, if still unverifiable, story. The image most often cited is Leonardo da Vinci’s The Last Supper, where Judas is painted having knocked over the salt. Because Judas was already marked as the betrayer, the salt he spilled became marked too. Tossing it over the left shoulder was said to blind the devil waiting there to claim you. Whether the painting caused the superstition or simply captured one that already existed isn’t something anyone can answer with confidence. Either way, the devil ends up on the left side of a lot of these stories, which is its own pattern worth noticing.

When the Church Wrote the Rules

Walking under a ladder gets its explanation from geometry as much as theology. A ladder leaned against a wall forms a triangle, and the triangle carried sacred weight in Christian symbolism because of the Trinity. Father, Son, and Holy Spirit. To walk through that triangle, the reasoning goes, was to walk through something holy and invite consequence for the disruption. It’s a tidy explanation. It also conveniently ignores the much more practical hazard of a person, or a bucket of something worse, coming down on your head. Sometimes superstitions and a safety warning end up saying the same thing for different reasons.

Black cats carry a heavier history, and it’s worth being precise about what actually happened rather than what gets repeated online. In 1233, Pope Gregory IX issued a decree called Vox in Rama, addressed to church authorities in Mainz, Germany. It responded to reports from an inquisitor named Konrad von Marburg, who claimed to have uncovered a satanic cult that worshipped a demonic figure described as half man, half black cat. The bull condemned that specific cult. It was not a papal order to exterminate cats across Europe. It was sent to a handful of named officials in one region, not broadcast to the whole of Christendom.

What that bull started didn’t stay in Mainz. Within a generation, testimony from witch trials elsewhere in Europe began naming cats, especially black ones, as the animal a witch might turn into or send to do her bidding. By 1484, Pope Innocent VIII issued his own decree, naming the cat the devil’s chosen creature and companion to every witch. What Gregory had aimed at one cult in Germany, Innocent turned into an accusation against an entire species across the continent. French and Belgian villages burned cats on holy days for centuries afterward. A practice Belgium still marks each year, now with stuffed cats standing in for the real ones.

The claim that a 13th-century pope single-handedly caused the Black Death by triggering a mass cat purge doesn’t hold up. The plague didn’t arrive until 1347, more than a century later. What does hold up is slower, and in its way worse. An idea aimed at one town in Germany took root across an entire continent, and outlived the men who wrote it by five hundred years.

Saints, Blacksmiths, and the Devil’s Hoof

The lucky horseshoe traces back to a folk legend about Saint Dunstan, a 10th-century English blacksmith who later became Archbishop of Canterbury. In the most repeated version, the devil arrived at Dunstan’s forge disguised as a traveler and asked him to shoe his horse. Dunstan recognized who stood before him, and instead of shoeing the horse, he nailed the shoe straight onto the devil’s own leg. The devil howled and begged for it to be removed. Dunstan agreed, but only after the devil swore he would never enter a home with a horseshoe hung over the door.

It’s a story that shows up in variations across centuries of English folklore, retold in an 1871 illustrated book by Edward Flight. It remains the most cited origin for a superstition most people practice without knowing any of this history. Whether the devil ever really stood in that forge is not something history can confirm. The legend is the point. It gave a strange practice a story worth remembering. That story is why the horseshoe still gets nailed over doorways today, argued over endlessly for whether the ends should point up or down.

The Superstition Never Really Leaves the Room

What’s strange is how little any of this has faded with modern times. Professional athletes perform in one of the most statistically measured environments in modern life. Yes, still build rituals around chance. Rafael Nadal is well known for lining up his water bottles in a precise arrangement before every match. A small act of order imposed on a game he can’t fully control. Baseball players tap the plate a certain number of times, follow the same sequence before stepping into the box, refuse to change a routine mid-streak. None of it is supported by any scientific evidence. All of it persists anyway, because the ritual isn’t really about the outcome. It’s about the feeling of having some type of control in the face of a result that hasn’t happened yet.

Social media has just given old superstitions a faster way to travel. The version of Bloody Mary most people know today is relatively young. The fears that shaped it are not. But behind it, a mirror as a doorway. A name that shouldn’t be spoken carelessly, are as old as the fear of one’s own reflection. New platform, same instinct.

Superstition, in the end, isn’t really about the ladder or the mirror or the cat. It’s about what people do when the world refuses to explain itself. Somewhere between fear and control, a habit gets born, gets a story attached to it, and gets handed to the next generation without anyone stopping to ask why. Most of us will keep knocking on wood long after we’ve read exactly where it might, or might not, have come from. That contradiction is the whole story. As for me, I’m the salt guy.