In ancient goddess-worshipping cultures 13 was also a lucky number--because it corresponded to the number of lunar (menstrual) cycles in a year (13 x 28 = 364 days). (The "Earth Mother of Laussel," a 27,000-year-old carving near the Lascaux caves in France, depicts a female figure holding a crescent-shaped horn bearing 13 notches.) Later, according to some historians, 13 got a bad name-particularly among early Christian patriarchs--because it represented femininity.

Superstitions about Friday

Many people consider Friday unlucky because that's the day of Jesus' Crucifixion, but historians believe the superstition goes much farther back and has something to do with the sacrifices offered to the goddess Frigg (goddess of marriage and fertility) or Freya (goddess of sex and fertility) or both, in Norse mythology.

Frigg/Freya's emblem was the fish, which was associated with the worship of love and was offered by the Scandinavians to their goddess on the sixth day of the week, Friday. But the worship of love on Fridays, according to Popular Superstitions, developed into "a series of filthy and indecent rites and practices."

According to Emery, Friday was considered lucky, especially as a day to get married, because of its associations with love. In other pagan cultures, Friday was the sabbath, a day of worship. Once Christianity entered the scene, Freya-whose sacred animal was a cat--was recast in folklore as a witch. In the Middle Ages, Friday was known as the "Witches' Sabbath."

Later, early Christians began attributing just about everything terrible to Friday: Eve offering Adam the apple in the Garden of Eden; Abel's murder by his brother, Cain; St. Stephen's stoning; the Massacre of the Innocents by Herod; the flight of the children of Israel through the Red Sea; the Great Flood; the destruction of the Temple of Solomon; and the Confusion of Tongues at the Tower of Babel.

Which brings us to.

Superstitions about Friday the 13th

Add it up, and Friday the 13th is clearly doomed as a bad luck kinda day.

Most historians believe the main reason--in addition to all the gloom and doom you just read above--stems from the Last Supper. Jesus and his 12 disciples gathered in the Upper Room, where Jesus predicted that one of them would betray him. Here is how Jesus' words are portrayed in the Gospel: "Jesus answered them, Have not I chosen you twelve, and one of you is a devil? He spake of Judas Iscariot . . for he it was that should betray him." (John 6: 70-71)

And that scene, of course, set the stage for the Crucifixion, on Good Friday.

Some sources add an additional wrinkle, however. They pinpoint the origin of Friday the 13th-phobia to a specific historical event: the rounding up of the Knights Templar for torture and execution by King Philip IV of France on Friday, October 13, 1307.

Read and weep. Shiver with fear. Dive for cover.