Just like walking under a ladder, crossing paths with a black cat or breaking a mirror, many people hold fast to the belief that Friday the 13th brings bad luck. Though it's uncertain exactly when this particular tradition began, negative superstitions have swirled around the number 13 for centuries.
Western cultures have historically associated the number 12 with completeness (there are 12 days of Christmas, 12 months and zodiac signs, 12 labors of Hercules, 12 gods of Olympus and 12 tribes of Israel, just to name a few examples). 13 though...poor thing, people just don't like it.
According to the Stress Management Center and Phobia Institute in Asheville, North Carolina, more than 80 percent of hi-rise buildings in the United States do not have a 13th floor, and the vast majority of hotels, hospitals and airports avoid using the number for rooms and gates as well.
There's even a name to describe the irrational dread of the date: paraskevidekatriaphobia -- a specialized form of triskaidekaphobia, a fear of the number 13.
In his book "Extraordinary Origins of Everyday Things," Charles Panati traces the concept of the cursed back to Norse mythology, when Loki, the god of mischief, gate-crashed a banquet in Valhalla, bringing the number of gods in attendance to 13. Deceived by Loki, the blind god Hodr was tricked into shooting his brother Balder, the god of light, joy and goodness, with a mistletoe-tipped arrow, killing him instantly.
From Scandinavia, Panati explains, the superstition then spread south throughout Europe, becoming well established along the Mediterranean by the start of the Christian era. It was here that the unsettling power of the numerals was cemented through the story of the Last Supper, which was attended by Jesus Christ and his disciples on Maundy Thursday. The 13th and most infamous guest to arrive, Judas Iscariot, was the disciple who betrayed Jesus, leading to his crucifixion on Good Friday.
In Biblical tradition, the concept of unlucky Fridays, stretches back even further than the crucifixion: Friday is said to be the day that Adam and Eve ate the forbidden fruit from the Tree of Knowledge; the day Cain murdered his brother, Abel; the day the Temple of Solomon was toppled; and the day Noah's ark set sail in the Great Flood.
It wasn't until the 19th century, however, that Friday 13th became synonymous with misfortune: As Steve Roud explains in "The Penguin Guide to the Superstitions of Britain and Ireland," the combination of Friday and the number 13 is a Victorian invention. In 1907, the publication of Thomas W. Lawson's popular novel "Friday, the Thirteenth" captured the imagination with its tale of an unscrupulous broker who took advantage of the superstitions around the date to deliberately crash the stock market.
Does Friday the 13th have to be bad luck? No! The ancient Chinese regarded the number 13 as lucky (they don't like 4). The ancient Egyptians also thought 13 brought good luck.