The calendar aligns at least once a year to offer us a Friday the 13th. Prices for airline tickets drop, your superstitious boss skips key meetings, and you're simply waiting for something strange to happen.

In addition to being associated with ill luck, Friday the 13th has been the subject of a late 19th-century secret organization, a novel from the early 20th century, a horror film series, and two ungainly terms: paraskavedekatriaphobia and friggatriskaidekaphobia.

Many people believe that Friday the 13th brings bad luck, just as going under a ladder, running into a black cat, or shattering a mirror. Though it's unclear when this particular superstition started, the number 13 has been associated with bad luck for ages.

Origin of Friday the 13th

There are a variety of reasons why this belief exists, including the tale of Jesus' final supper and crucifixion, in which 13 people were present in the Upper Room on Maundy Thursday, the night before his death on Good Friday. While both Friday and the number 13 have a bad reputation, there is no indication that the two were regarded particularly unlucky until the 19th century.

The superstition appears to be linked to the gruesome tragedy of the Templar Trials, which began on Friday, October 13, 1307, when Philip IV of France and his advisors seized the Templars' treasure. The number 13 has a bad reputation because of an old Norse story about 12 gods enjoying a supper party in Valhalla. Hör planned for Balder to be shot with a mistletoe-tipped arrow by the trickster god Loki, who had not been invited.

In addition, 13 became unlucky because of this significant occurrence in Norse mythology. Gioachino Rossini, who died on Friday the 13th, was the subject of an early English-language reference: Roseni was surrounded by admiring friends to the end, and it's surprising that his death occurred on Friday the 13th of November since he believed Fridays were unlucky days and thirteen was an unlucky number, as many Italians do.

Thomas W. Lawson's famous novel Friday, the Thirteenth may have contributed to the spread of superstition in 1907. For example, an unethical broker exploits Friday the 13th to generate a Wall Street panic.