Origin of bad luck and the number thirteen - how they met, became lovers and only later showed each other the door.
Before the days of the British aristocracy, there were mathematicians. These ancient folks had little better to do than watch the shadows move across the ground in front of their caves. They got curious. They couldn't hunt for themselves because of an ingrown toenail, but they could observe with severity.
Twelve generations of these observations caused the cave walls to be littered with drawings of the sun and the arch of the sky and the idea that there must be some curve to the earth. They didn't have the words to describe what they could diagram in pictures.
They figured out a year ( again over many generations ) was a cycle of thirteen months.
The didn't figure it out like you figure out a Rubik's cube. More like their record keeping was so vast that it revealed itself in obvious patterns to anybody daring to light a match in the depths of their cave -- which was also where they kept their kim-chee ( did I mention they were Korean and had a penchant for spicy, rotting foods? )
How thirteen became unlucky was when a young boy got into an argument with a friend from another village. One boy from the cave called his friend a liar because the boy claimed to know the cycle of life was 12 months long -- all the while the boy from the cave knew it was 13.
The elders from the village came to verify the claims -- and, heard there was some spicy, rotting delicacies to be tried.
On the day the village entered the cave, without the safety of modern technology, an earthquake shook the mountain in which the cave was burrowed.
A boulder landed in front of the cave keeping all the kim-chee eaters hostage. And, while anybody who passed by could hear the people asking -- "A little help please?" -- as if they needed another roll -- the rocks of the cave and the boulder were too large-dimensional and vectored.
All the people died.
The story was told and re-told to many young people as an allegory about why you shouldn't argue. The young people eventually summarized it into -- 13 is an unlucky number --.
Hmmm.. or something like that.