Friday the 13th, also known as Black Friday in some countries, is considered an unlucky day in Western superstition. It occurs when the 13th day of the month in the Gregorian calendar falls on a Friday. There is no written evidence for a “Friday the 13th” superstition before the 19th century, and the superstition only gained widespread distribution in the 20th century. The fear of the number 13 has been given a scientific name: triskadekaphobia; and on analogy to this the fear of Friday the 13th is called paraskevidekatriaphobia, from the Greek words Paraskeví (Παρασκευή, meaning “Friday”), and dekatreís (δεκατρείς, meaning “thirteen”).
It’s not known for certain how the superstition surrounding this day arose, but both Friday and the number 13 are connected with the crucifixion of Christ (Friday being the day the crucifixion took place, commemorated weekly in Catholic practice, and 13 being the number of people present at the Last supper). According to Phillips Stevens, Jr., associate professor of anthropology at the University at Buffalo (SUNY), “There were 13 people at the table (at the Last Supper) and the 13th was Judas. The Last Supper was on a Thursday, and the next day was Friday, the day of crucifixion. When ’13’ and Friday come together, it is a double whammy.”
Friday has been considered an unlucky day to undertake journeys or begin new projects at least since the 14th century, as witnessed by Chaucer’s Canterbury Tales.
However, folklorists maintain that there is no written evidence for a “Friday the 13th” superstition before the 19th century. An early documented reference in English occurs in Henry Sutherland Edwards’ 1869 biography of Gioachino Rossini, who died on a Friday 13th:
He [Rossini] was surrounded to the last by admiring friends; and if it be true that, like so many Italians, he regarded Fridays as an unlucky day and thirteen as an unlucky number, it is remarkable that on Friday 13th of November he passed away.
Other possible contributing factors include:
In numerology, the number twelve is considered the number of completeness, as reflected in the twelve months of the year, twelve hours of the clock day, the twelve deities of Olympus, twelve tribes of Israel, twelve Apostles of Jesus, the 12 successors of Muhammad in Shia Islam, twelve signs of the Zodiac, the 12 years of the Chinese Buddhist cycle, etc. In contrast the number thirteen is considered irregular, transgressing this completeness.
There is a superstition, thought by some to derive from the Last Supper or a Norse myth, that having thirteen people seated at a table results in the death of one of the diners.
On Friday, 13 October 1307, hundreds of the Knights Templar were arrested in France, possibly giving rise to the fear of a curse on that day. This connection between the Friday the 13th superstition and the Knights Templar was popularized in Dan Brown’s 2003 novel The Da Vinci Code and in John J. Robinson’s 1989 work Born in Blood: The Lost Secrets of Freemasonry, and also in the Maurice Druon historical novel series: “The Accursed Kings” (French: Les Rois Maudits). However, experts agree that this is a relatively recent correlation, and most likely a modern-day invention.