Check today's date. It's Friday, Friday the 13th or as some people would say the unluckiest day on the calendar. It's very common to not have a 13th floor in a hotel or a house numbered 13. Even flight tickets are cheaper on this so called ominous day. Infact, the fear of Friday the 13th, friggatriskaidekaphobia or paraskevidekatriaphobia, is recognised as a psychological condition.
I have a simple question though, why just the number 13, why not 7, 89, or 74349. And why only Friday of the seven boring days of the week? I tried to find the answers to these questions and here's what I've come across:
1. Jesus Christ was crucified on a Friday and there were 13 people present at the Last Supper.
Judas, the one who betrayed Jesus, was the thirteenth person present at the Last Supper. And not only this, many negative Biblical events took place on a Friday, for instance, the expulsion of Adam and Eve from the Garden of Eden, and the start of the Great Flood.
2. Number 12 is viewed as a whole in numerology (for instance, 12 signs of the zodiac, the 12 Apostles of Jesus, 12 gods of Olympus, 12 labors of Hercules, 12 tribes of Israel, and 12 successors of Muhammad in Shia Islam). Any number over this is considered discordant, or unwhole, by numerologists.
3. Another origin of this myth can be traced back to 1307 when Philip IV of France arrested hundreds of the Knights Templar.
It is mentioned in Maurice Druon's historical novel The Iron King (1955), John J. Robinson's Born in Blood: The Lost Secrets of Freemasonry (1989), Dan Brown's The Da Vinci Code (2003) and Steve Berry's The Templar Legacy (2006).
4. In the 19th century, several novels and biographies popularised the idea of Friday the 13th being an unlucky day.
One example is a novel titled Friday, the Thirteenth by Thomas W. Lawson.
Another example is Henry Sutherland Edwards' biography of Gioachino Rossini (1869), who died on Friday the 13th. Here's the documented reference from the biography itself:
He [Rossini] was surrounded to the last by admiring friends; and if it be true that, like so many Italians, he regarded Fridays as an unlucky day and thirteen as an unlucky number, it is remarkable that on Friday 13th of November he passed away.
However, these are just some of the 'assumptions' (among thousand others!). It is still unclear why Friday the 13th is considered as the day of ill-repute.
And it's not just the number 13, there are other dates that are considered unlucky in other cultures. For instance, in Italy, Friday the 17th is considered ominous.
Other ones being Spain and Greece, where Tuesday is an unlucky day.
According to science, there's nothing special about Friday the 13th. It's a constructed belief and you can blame your ancestors for passing it over the generations. And for all those who take it as seriously as I take chocolate sauce on my brownies: beware of black cats, ladders and meteors... and your neighbour.