Do any irrational fears hold you back? It’s one thing to be afraid of heights or spiders. They call them “irrational” fears, but they still make sense.

But when you go out of your way to invent a fear, that’s truly irrational. Case in point, paraskavedekatriaphobia, or fear of Friday the 13th. This is a specialized form of triskaidekaphobia, or fear of the number 13.

Fear of Friday the 13th is a phobia of pure choice. Studies have shown that about 10% of Americans are afraid of it, but they have no idea why.

No one can really say where this fear comes from, but most people say it’s a combination of the fear of Friday and the fear of 13. Really, have you ever heard of the fear of Friday? When you go to work on Friday, are you terrified of all the bad things that will happen, or are you looking forward to the weekend?

Anyway, many reasons for this fear have been suggested:

- The number 12 is sometimes considered the number of completeness (12 months of the year, 12 signs of the zodiac, 12 hours of the clock, 12 tribes of Israel, 12 Apostles of Jesus, 12 gods of Olympus, etc). Adding one more to make it 13 breaks this completeness.

- There were 13 people at the Last Supper, and Judas was the 13th person to arrive.

- Jesus was crucified on a Friday.

- Some people say that Adam and Eve ate the forbidden fruit on a Friday, and that the Great Flood began on a Friday.

- There is a superstition, possibly derived from the Last Supper or a Norse myth, that having 13 people seated at a table will result in the death of one of them.

- Friday has been considered an unlucky day at least since The Canterbury Tales were written in the 14th century.

- Many professions have regarded Friday as an unlucky day to undertake journeys or begin new projects.

- Black Friday has been associated with stock market crashes and other disasters since the 1800s.

- The goddess Frigga (for whom Friday is named) was banished by the Christians and labeled a witch. Every Friday, she was believed to meet with 11 other witches plus the devil, for a total of 13.

- King Philip secretly ordered the mass arrest of all the Knights Templar in France on Friday, October 13, 1307. This story is told in The Da Vinci Code, but some people think this connection wasn’t made until the 20th century.

- In 1907, Thomas W. Lawson published his popular novel Friday, the Thirteenth, in which a stockbroker takes advantage of the superstition to create a Wall Street panic on Friday the 13th. References to Friday the 13th were almost nonexistent before 1907.

- In the Roman calendar, Friday was devoted to Venus. In the Norse calendar, Friday was named after Frigga or Freya. The Christians didn’t like strong women, so they vilified Friday.

- There are 13 months in the pagan lunar calendar.

- Friday was Hangman’s Day in Britain.

- Apollo 13 was launched at 13:13 CST, and its oxygen tank ruptured on April 13, 1970.

None of these sound like really good reasons, do they? A 2000 superstition survey found this:

“…while only 13 percent of the population at large believes that Friday the 13th is an unlucky day, 30 percent of 18- to 24-year-olds think so. Interestingly, the nine installments of the horror movie series Friday the 13th were released during this set’s formative years (1980-1993). Coincidence? Perhaps.”

This is an entirely made up fear, but it affects many people. Some people avoid their normal routines on this day, to the tune of an estimated $800 to $900 million in lost business in the U.S.

It becomes a self-fulling prophesy. If you expect Friday the 13th to be unlucky, you’ll find evidence to support that. I’m sure some bad things happened on Friday the 13th, but are they really that much more significant than September 11th, Hitler’s invasion of Poland, Lincoln’s Assassination, etc?

How about this: decide that from now on, Friday the 13th is good luck. Just see what happens today. (You’ll get another chance next month.)

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