I am going to stick my neck out, metaphorically speaking, and claim that the black cat superstition may have started with a Papal Bull of 1233 made by Pope Gregory IX. In the 13th century the church wanted to root out heretics and they sent an inquisitor whose name was Konrad von Marburg to begin an inquisition in Mainz, Germany. He reported that he had uncovered a satanic cult which worshipped devils in the forms of a demonic man and a diabolical black cat. However, a Papal official reported that the Konrad inquisition was false and that he had forced innocent people to confess by threatening them with burning at the stake.
The reports on this incident appear to have become muddied over time because Dr. Desmond Morris in his book Cat World states that Pope Gregory IX initiated the feline holocaust in Europe which continued through the Middle Ages and beyond. He did so by denouncing the black cat as diabolical or as representing the devil in his Papal Bull, which gave his “official blessing to the widespread persecution of cats which was already occurring locally in Europe. Dr. Morris states that Pope Gregory “set the course for five centres of cat hatred, torture and burning.”
Another source states that the 1233 Papal Bull is referred to as Vox in Rama. It was a letter which condemned the heresy of Luciferianism which was apparently rife in Germany at the time and he authorised the preaching of a crusade against it. This crusade led to the Konrad von Marburg report on the worship of a demonic, diabolical black cat. But it appears to have been fabricated. However, perhaps the damage was already done for black cats because it created the superstition which led to their persecution for centuries. Superstition regarding black cats and cats in general in developing countries is still very much alive and quite powerful to the detriment of the welfare of cats almost 800 years later. This highlights the innate fear of humans and their propensity to be superstitious. The conspiracy theories on the Covid-19 vaccines are another current example.
This is my interpretation based upon several sources but I’m not an expert on this sort of cat history. Sometimes people ask the question as to why Pope Gregory IX believed that cats were evil. I don’t think he did personally believe that they were evil; it’s just that the report that came back to him stated this. Other historians state that the Konrad report was complete fiction.
The Museum Hack website quotes the Papal Bull referred to verbatim but translated to English and the bit regarding the black cat is as follows. This seems though to be a translation of the Konrad report into the worship of a demonic black cat which seems to have been incorporated into the Papal Bull.
Afterwards, they sit down to a meal and when they have arisen from it, the certain statue, which is usual in a set of this kind, a black cat descends backwards, with its tail erect. First the novice, then the master, then each one of the order who are worthy and perfect, kiss the cat on its buttocks. Then each [returns] to his place and, speaking certain responses, they incline their heads toward to cat. “Forgive us!” says the master, and the one next to him repeats this, a third responding, “We know, master!” A fourth says “And we must obey.”
The reference for the quote is a Quora.com response to the question Is the Vox in Roma authentic? It is dated June 1, 2018.
SOME ARTICLES ON SUPERSTITION: