The Bull, the Black Cat, and the Plague That Wasn’t Their Fault
A medieval pope really did write about a black cat. The story that this caused the Black Death is one of the most repeated pieces of nonsense on the internet.
The story goes like this. In 1233 Pope Gregory IX issued a bull, Vox in Rama, declaring black cats to be servants of Satan. Europe obediently exterminated its cats. Freed of predators, the rat population exploded. A little over a century later the Black Death arrived and killed a third of the continent. Cats had tried to save us, and we killed them first.
It is a wonderful story. It is on thousands of websites. Almost every link in it breaks when you pull on it.
What the document actually says
Vox in Rama is real. It was addressed to German authorities, prompted by the inquisitor Konrad von Marburg’s reports of a Luciferian heresy in the Rhineland. Among the alleged initiation rites it describes, a black cat descends backwards and the initiates kiss it.
That is the extent of it. It is a document about a specific heresy in a specific German region, describing what heretics were accused of doing. It contains no order to kill cats, no instruction to the faithful anywhere, and no programme of extermination.
The gap nobody mentions
Vox in Rama is from 1233. The Black Death reached Europe in 1347. That is a hundred and fourteen years — roughly four generations — during which cats are documented living in European homes, monasteries, ships and mills, doing the job they had always done.
A continent does not eradicate a self-replicating, semi-feral animal that lives in every barn and grain store, and then fail to notice for a century.
And the plague did not work the way the story needs it to
The tidy rat-flea-human chain has been under serious pressure for years. Modelling work on the spread of the fourteenth-century pandemic has found that human ectoparasites — body lice and human fleas — fit the observed pattern of transmission considerably better than rat fleas do. The speed and geography of the outbreak are hard to reconcile with a rat-dependent model.
If a meaningful share of transmission was human-to-human, then cats were never the missing defence in the first place.
What is true, and is worse
None of this means medieval Europe was kind to cats. It was not. Cats were killed in organised public rituals in parts of France well into the early modern period — burned in bonfires at midsummer as entertainment, with the crowd and sometimes the king in attendance. Black cats in particular attracted suspicion during the witch trials, and that association is durable enough that shelters in some countries still report black cats waiting longer for homes.
The real history is grimmer than the myth, and it does not need a papal conspiracy or a plague to make its point. People did this for fun, at festivals, for centuries.
Why the myth is so sticky
Because it is morally satisfying. It gives cats a martyrdom, gives superstition a body count, and hands us a clean villain. Real history rarely arranges itself that neatly, and the version where ordinary townspeople burned cats for an afternoon’s amusement is harder to enjoy retelling.
Be suspicious of any historical claim that flatters the animal you already like.
This is general information, not a diagnosis.
Every cat is a specific animal with a specific history. Use this to ask your vet better questions — not to replace the examination. Spotted an error? Tell us and we will correct it in public.
