Friday the Thirteenth

I have never really understood why people get so superstitious about Friday the Thirteenth.  I've had colleagues who'd take the day off and stay at home rather than risk the 'bad luck' the day allegedly brings.  I can't say that I've ever seen any evidence of increased incidences of bad luck on Fridays which happen to also be the thirteenth of any given month.  Unless you live in Crystal Lake, of course, in which case you apparently run an increased risk of being menaced by a machete wielding maniac in a hockey mask.  Those films really haven't helped the reputation of the day, (although, as I vaguely recall from the handful I've seen, most don't actually take place on a Friday the thirteenth), as a magnet for ill luck.  But why should a combination of Friday and thirteen be considered so unlucky? 

I mean, thirteen itself always seems to have been adjudged to be an unlucky number.  I've lost count of the number roads which don't have a house or building numbered thirteen.  They usually just skip from twelve to fourteen (or eleven to fifteen if they have odd and even numbers on opposite sides), but there's at least one road here in Crapchester which had a number thirteen which was subsequently changed to 11A, (presumably at the behest of superstitious occupants).  Back in my home town, the street I grew up on was disrupted when the original buyer of what was to have been number thirteen, (the road was still being built when we moved in and, when originally sold, the houses only had plot numbers, the actual numbering scheme being applied as the first houses were completed), objected and the numbers had to be adjusted accordingly.  Anyway, the reasons for thirteen being considered unlucky seem to have vanished into the mists of time - it could be because there were thirteen people at the Last Supper, or it could have something to do with a supressed lunar cult, but the truth is that nobody knows.

But why, when combined with a Friday, should it become even unluckier?  After all, Friday is, generally speaking, the last working day of the week.  Traditionally, it was the day when people were paid, (in the days of weekly pay packets).  Consequently, it is a day most people look forward to, rather than dread, (that's usually reserved for Mondays, when most of us return to work after the weekend - why isn't Monday the thirteenth considered unlucky?).  We can't even blame it on the Catholics - they don't associate thirteen with bad luck, but rather with St Anthony of Padua, (today was his feast day, in fact).  Indeed, in Italy, thirteen is considered to be a lucky number, so presumably today is seen as an especially lucky day: feast day, end of the week and a thirteen).   I have to say that nothing bad has happened to me today, (perhaps I have some Italian blood in me somewhere), so clearly the Italians' irrational belief in thirteen being lucky is more valid than our irrational belief that it is unlucky.