This was a club that used to get together once a month and try to dispel that myth, that superstition, that it's unlucky to sit 13 to a table. HANSEN: OK, now tell us, then, about the 13 Club.

It's only in the centuries since that there's been sort of confusion and alternative theories that have come up. And at the time, everyone knew, really, the origin of the superstition, and it was the 12 plus one of Christ and the disciples at the Last Supper. LACHENMEYER: The number 13-first record of it being a superstition was in the late 17th century, and the first incarnation of unlucky 13 was '13 at a table.' If you sit 13 people at a table, one will die within a year. HANSEN: How did the number 13 first begin to appear unlucky? NATHANIEL LACHENMEYER (Author, '13'): Hi, thanks for having me.

In his new book '13: The Story of the World's Most Notorious Superstition,' Nathaniel Lachenmeyer examines the unlucky number 13, and he's in our New York bureau. Today, although a Sunday, is still the 13th day of the month. The number 13 still carries certain superstitious weight. Superstitions often begin because we seem to get lucky or unlucky depending on whether we engage or avoid certain behaviors. We throw salt over our shoulders or count the cracks in the sidewalk to avoid breaking our mother's back. We don't change socks or headgear during the playoffs. We avoid black cats and walking under ladders. The condition manifests itself in many different ways. Whether we are willing to admit it or not, many of us are superstitious.

Unlucky 13 book