In numerology, the number twelve is favored for its association with completeness: twelves months in a year, twelve hours on a clock, twelve Apostles, twelve tribes of Israel, twelve gods of Olympus, etc. Thirteen, then, is the perversion of this perfect completeness; twelve's a party, thirteen a crowd. Some believe that seating thirteen people at a table will result in the death of one, a superstition inspired by both The Last Supper and an old Norse myth. But why Friday? Bad end-of-week vibes can be traced back to as early as the 14th century, in Geoffrey Chaucer's The Canterbury Tales.
This year's Friday the 13th is unusual:
]]>There are three of them: Jan. 13, April 13 and July 13. The freaky thing? The dates fall exactly 13 weeks apart. That hasn't happened since 1984.