Various theories have emerged about the origin of the Friday 13th superstition. In numerology, the number twelve is considered the number of completeness, as reflected in the twelve months of the year, twelve signs of the zodiac, twelve hours of the clock, twelve Apostles of Jesus etc. In contrast, the number thirteen was considered irregular, transgressing this completeness.
There is also a biblical reference to the unlucky number 13. Judas, the apostle who betrayed Jesus, was the 13th guest to the Last Supper. It was also believed that Jesus was crucified on a Friday, making it an unlucky day.
Friday has also been considered cursed since the end of the 14th century when Chaucer wrote in the Canterbury Tales “and on a Friday fell all this misfortune.” As well, Black Friday has been connected with stock market crashes and other disasters since the 1800s.
According to the Stress Management Center and Phobia Institute in Asheville, North Carolina, an estimated 17 to 21 million people in the United States are affected by a fear of this day. “It’s been estimated that $800 or $900 million is lost in business on this day because people will not fly or do business they would normally do.”