Today is Friday the 13th, the last Friday the 13th of the millennium, a double-whammy of a day fraught with wicked omens -- especially for triskaidekaphobics, those haunted souls who have a crippling fear of that unmentionably evil integer that looms between 12 and 14.

But does number you-know-what really have the power to wreak havoc in our lives? Terri Bonebright, assistant professor of psychology at DePauw University, believes that Friday the 13th is nothing more than a bogeyman date that people use to account for the snags and snafus of everyday life.

"It all revolves around superstition," Bonebright said in a press release. "In the case of Friday the 13th, people have been told it will be a bad day, so they selectively remember all the bad events that occur throughout the day."

So if you get fired from your job today, or smash up your car, you can blame it on Friday the 13th. Superstition, Bonebright said, provides us with an excuse for explaining away our mistakes and disgraces. In other words, it's an easy way to rationalize the screw-ups for which we ourselves are ultimately responsible.

Still, engineers and architects go to great lengths to soothe our superstition. Skyscrapers and hotels have no 13th floor; airplanes have no 13th aisle. But the joke is on triskaidekaphobics, of course, since the 13th aisle is sitting right there behind the 12th, obviously -- it's just labeled as 14 to hoodwink you into relaxing.

So where does it come from -- the fear of 13? Its origins can be traced to Norse mythology and a dinner party at Valhalla, home of the god Odin, where Odin and 11 of his closest god-friends were gathered one night to party. Everyone was having fun, but then Loki, the dastardly god of evil and turmoil, showed up uninvited, making it a crowd of 13. The beloved god Balder tried to boot Loki out of the house, the legend goes, and in the scuffle that followed he suffered a deathblow from a spear of mistletoe.

From that mythological start, the number 13 has plowed a path of devastation through history. There were 13 people at Christ's Last Supper, including the double-crossing Judas Iscariot. The ill-fated Apollo 13 lunar mission left the launching pad at 13:13 hours and was aborted on April 13. Friday hasn't been much kinder to us. Friday was execution day in ancient Rome -- Jesus was crucified on a Friday. Put it all together, and Friday the 13th spells trouble for triskaidekaphobics. It's a testament to the phobia's prevalence that Hollywood was able to parlay our fear into a hugely successful series of slasher movies starring a hockey-masked guy named Jason.

But triskaidekaphobia isn't an exclusively American affliction. Italians omit the number 13 from their national lottery. There is a hush-hush organization in France whose exclusive purpose is to provide last-minute guests for dinner parties, so that no party host ever has to suffer the curse of entertaining 13 guests.

Hardcore triskaidekaphobics say that 13 has the power to affect not only their own personal lives, but global events as well. According to Malcom Riviera, founder of the Triskaidekaphobia Illuminatus Society, civic authorities recognize the malicious power of 13 and are willing to bend the rules to help people avoid it. In a 1998 interview, Riviera said, "The way it can affect power is: The unconscious awareness of 13's qualities causes leaders to make decisions based on their aversion to it."

So how bad can the phobia get? Donald Dossey, director of the Phobia Center in Asheville, N.C., says that the various effects of triskaidekaphobia can range from a mild, nagging sense of doom to full-blown obsessive behavior. Some people refuse to get out of bed on Friday the 13th, Dossey says.

Bonebright says that most triskaidekaphobics never experience such a crippling level of fear. If your dread of 13 begins to rule your life, she says, you should seek professional help.

But it can probably wait until Monday.