Friday 13th friggatriskaidekaphobia - Lucky for some.

Most people over here in the 'western' side of the world know of the superstition of bad luck on Friday 13th. There's even a name for fear of the possible doom of the day: "friggatriskaidekaphobia" and also "paraskavedekatriaphobia". I'd be doomed trying to pronounce it, and it's so bad they've named it twice.

No documented hard evidence of when Friday 13th became bad can be found. It is known to be a centuries old belief and some documents state these kinds of 'facts' as reasoning:-
13 people at the last supper
Jesus was crucified (Friday).

Code of Hammurabi which is the worlds oldest known legal document was said to have been written without a law 13 because of the ill fate that it held. More likely it was mis-numbered.

The fact that numerologists, scientists, philosophers etc like number 12 as an 'end game' means that 13 is pushed outside the favoured circle. We have 12 months, 12 zodiac signs, 12 days of Christmas, 12 tribes of Israel, 12 Gods of Olympus , 12 Norse Gods, then follows the mischievous 13th - Loki and so on. Poor number 13 has been kicked out into the twilight for centuries.
Loki caused a lot of trouble...source

As for the Friday issue, this has a little more standing in historical events. Jesus was crucified on a Friday (although some Christians say that was a good thing as it fulfils the prophecy and it's how and why we're still here). Eve supposedly gave Adam the forbidden fruit on a Friday, Cain killed Abel on a Friday. (Whether we like it or not, Christianity has threads woven into every corner of our society, good and bad and this influences thought processes until over centuries it becomes tradition).
Executions in old Rome were standard on a Friday.
In old America executions were also traditionally held on a Friday, so definitely unlucky for some.
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From earliest times to somewhere around the 1400's ritual magic was often practised among the elites of western Europe and through the mix of Pagan, Celtic and Roman influence in the UK and Friday was an important day.
Friday was said to have belonged to the goddess Venus and her name, as well as the names of angels, were invoked to help magicians attain their ends.

Actual FRIDAY 13TH as a whole unit wasn't documented at all as particularly lucky or unlucky universally across the western part of the world until late 1800's and as with all great Victorian traditions, it caught on as popular then became 'a thing' until now, for some people it is a very real fear.

I always found I was luckiest, if that really is a thing, on Friday 13th.
However, my reasonings have since been proven (by myself) that it's mainly just a state of mind.

As I grew up my mum used to tell us kids family tales. The thing is most of it was BS or at the very least a convoluted and extracted version of the truth. Once she told us that our Great Grandfather was the famous Nosmo King and he was a stage man, ventriloquist, magician etc. In fact the part of what he did was correct see here but the name and the story of how he got it was complete mishmash. He was not Nosmo King but in fact Professor Nomis Cross (Simon backwards)
Professor Nomis Cross, great granddad, with ventriloquist dummy Ally Sloper

But I digress. The reason I wrote that was to point out the error of her ways.

Now, she ALWAYS told me that I was the 13th grandchild, and she was the 13th child and that we were both born on a Friday. So for many, many years I was convinced that Friday 13th was a good day for me, against all traditional thinking. Indeed, there have been interviews at which I excelled, the odd lottery win, a surprise promotion, all on a Friday that was the 13th.

Two things I have since thought of and discovered. I have had an equal amount of bad luck on Friday 13ths, and no change in life at all on some. So the odds are that as it's a Friday and the end of the average working week, many things will change in a person's life. You'll get fired, you'll get promoted, the lottery runs on a Friday, interviews happen any day of the week but you can make a bigger impact at the end of the week as decisions need to be made and you're fresh in their minds...

Also, I have since discovered that my mother was in fact born on a Tuesday, although she was the 13th child - so half true.
I have also found out that I was in fact the 15th grandchild but I WAS born on a Friday.

So you can see how the mishmash of ideas came about.

So in conclusion, being told that I was born the 13th grandchild, to the 13th child, both born on a Friday merely suggested to me that it was a lucky day. Then when something good happened to correspond with that day I would remember it, if nothing happened or the result was poor I would forget.

So despite the superstitions and tales from mixed up stories over the centuries - it is all a matter of the mind.

Friday 13th is simply just another day in the year.