Today is Friday the 13th, a date commonly associated with bad luck. You best keep an eye out for black cats crossing your path, stay away from mirrors and ladders, and, please, don't spill the salt.
For the next 24 hours or so, millions of superstitious folks all over the country will refuse to drive, shop or work today in fear of encountering misfortune.
There are very few years when there are more than two Friday the 13th in a year. In 2009, there are three--one in February, March and November. The last time this occurred was in 1998.
So whether you are a paraskevidekariaphobe, (mildly suspicious) or a triskaidekaphobe (person with an irrational fear of Friday the 13th) you may want to beware this year.
If a month begins on a Sunday it will have a Friday the 13th. The longest it can go without a Friday the 13th is 14 months.
Journalist David Emery's Web site called urbanlegends.about is designed to debunk tall tales and legends. He claims the superstition is derived from myths about both Fridays and the number 13.
Emery believes that Fridays are hailed as a particularly significant day in the Christian tradition.
"First, there is Good Friday, the day Jesus Christ was crucified. But according to Christian lore, Adam and Eve also supposedly ate the forbidden fruit on a Friday, the Great Flood started on a Friday, the builders of the Tower of Babel were tongue-tied on a Friday and the Temple of Solomon was destroyed on a Friday," he says on his Web site.
Ironically, he notes, that the Bible doesn't specifically refer to any of these events occurring on Fridays. He believes the tradition stems from pre-Christian pagan cultures that hailed Fridays as holy days.
The word "Friday" is, in fact, derived from a Norse deity who was worshipped on the sixth day of the week and who represented marriage and fertility. Fridays in the early Norse culture were associated with love and considered a good day for weddings.
Over time, mythology transformed the Norse fertility goddess into a witch, and Fridays became an unholy Sabbath. Incidentally, the goddess' sacred animal was a cat, which may explain the legendary connection between witches and cats, as well as the superstition about black cats bringing bad luck.
Additionally, the sixth day of the week was also execution day in ancient Rome and later Hangman's Day in Britain.
According to Emery the number 13 also has mythological and religious symbolism.
"Both the Hindus and Vikings had myths involving 12 gods invited to a gathering. Loki, the god of mischief, crashed the party and incited a riot. This led to a tradition of 13 people at a dinner party being bad luck, ending in the death of those attending," he notes.
The Last Supper in Christian tradition hosted 13 people with one betraying Christ, and resulting in the crucifixion on a Friday.
In other cultures, the number 13 has been associated with death. The ancient Egyptians considered death a part of their ultimate journey, which took place in 12 stages. The 13th stage was death. Over time this tradition turned negative, eventually associating the number 13 with a fearful interpretation of death.
A particular event took place tying the two superstitions together.
On Oct. 13th, 1307, France's King Philip IV had the Knights Templar rounded up for torture and execution.
More recently there have been studies around the ominous date. In 1993 a study published in the British Medical Journal titled, "Is Friday the 13th Bad for Your Health?" mapped behavior and superstition around the date in the United Kingdom.
The authors of the article compared the ratio of traffic volume to the number of accidents on two different days, Friday the 6tg and Friday the 13th, over a period of years.
Incredibly, they found that in the region sampled, while consistently fewer people chose to drive their cars on Friday the 13th, the number of hospital admissions due to vehicular accidents was significantly higher than on "normal" Fridays.
Their conclusion: "Friday the 13th is unlucky for some. The risk of hospital admission as a result of a transport accident may be increased by as much as 52 percent. Staying at home is recommended."
According to other experts, Friday the 13th is the most widespread superstition in the United States today. Some people won't go to work on this day; some won't eat in restaurants; many wouldn't think of setting a wedding on the date.
Dr. Donals Dossy, a psychotherapist specializing in the treatment of phobias and the coiner of the term paraskevidekatriphobia, believes as many as 21 million people fear Friday the 13th.
Even sailors fear Fridays. One hundred years ago, the British government sought to quell once and for all the widespread superstition among seamen that setting sail on Fridays was unlucky.
A special ship was commissioned, named "H.M.S. Friday." They laid her keel on a Friday, launched her on a Friday, selected her crew on a Friday and hired a man named Jim Friday to be her captain. To top it off, H.M.S. Friday embarked on her maiden voyage on a Friday, and was never seen or heard from again.
One last theory is a novel one. A book titled "Friday, the Thirteenth" was published in 1907. Its topic was about dirty dealings in the stock market. It sold well. The premise behind it was Friday the 13th as a supremely unlucky day in the stock market. It was instantly adopted and popularized by the press.