There is an ancient legend.
Before man came to master fire and cultivate his food, he lived in perpetual fear. There existed creatures of such frightful appearance and terrible power that even the mightiest of warriors fell before them. When the creatures did not attack, there were the artifacts of doom, some enchanted by wicked sorcerers who lived in isolation, some appearing for no reason except to torment man. And in times when neither were to be found, the incomprehensible forces assaulted the refuges of man, with no purpose but that of destruction.
It is said in some circles that the mastery of fire is what allowed man to drive off the horrors of the world. The idea of a weak, powerless group gaining a bright, burning weapon against the night-things is certainly a comforting one, and is indeed believed by most of the world to be man's first step towards independence.
But it was not fire that led man to his mastery of Earth. It took another event for fire to even be a possibility. Given the millennia that separate us from that day, nobody knows the exact details of the event. But the legend goes something like this.
One night, a group of nomads squatted in a deep, dark cave, awaiting a creature. They had been on the run for a full cycling of the moon, and had gradually been picked down from a group of twenty to a group of four. The beast showed no signs of tiring, and could easily tear a person in half given the chance. A single glance into its eyes was enough to paralyze any man, regardless of his constitution. The creature had wandered the world for many, many years, terrorizing all who stumbled across it.
In a world of horrors, it was probably the least fearsome creature one could encounter.
In the deepest part of the night, the four heard the creature's dragging footsteps scrape across the entrance of the cave. They tried to remain silent, hoping to buy a few more precious seconds with which to make their peace. The knowledge of impending doom had been with them for some time now, but only here, in their last moments of life, did that knowledge become a solid reality. Huddling together, the four survivors awaited the creature, and the bloodshed that would follow.
As it rounded the corner, the group could barely make out the features of the thing that stalked them. It was twice the height of any normal man, and half the width. The eyes seemed far, far too large for the head, which jutted out from the rest of the skull by several hands. Its limbs ended not in hands and feet, but rather in large pads of slime, which still managed to grip with the strength of lion jaws. Turning its head, the creature saw the group, and bolted towards them.
But for the four survivors, the end never came.
Right as the creature came within striking distance, it was tugged back by four strands of knotted up reeds, one attached to each of the limbs. Losing its balance, the creature fell upon the ground, knocking its head against the stone floor of the cavern. Before it could regain its senses, three lithe, strong men beset upon it, two taking an arm and a leg each, and the third grabbing the face with one hand. Raising up the other, he placed two crudely carved rocks over the creature's eyes. The group watched in fascination as, instead of flinging them aside with a toss of its head, the creature writhed in pain, unable to get rid of the stones, which seemed to cling to its eyes.
Tying the creature's limbs behind its back, the men hefted it up, and chucked the monstrosity into a corner of the cave. Then, they led the four bewildered survivors out into the night, where six more men stood watch over the entrance. Two of them rolled a large boulder over to the entrance, and sealed it tightly shut. From inside, they could still hear the echoes of the creature's screams.
As the first three men led the original survivors away, the other six took up posts around the cavern. Legend has it that for many years afterwards, they would patrol the area, making sure the creature hadn't escaped from it's confines. At every winter solstice, they would descend into the cavernous prison, and carefully replace the bindings and stones before sealing it once more.
As for the men who captured the creature, they went on to spread their knowledge across the globe. Tales from all corners of the Earth say they had decided to turn against the creatures which stalked them in the night, and make the world safe for man. That such a gargantuan effort was both planned and successfully implemented by a mere three individuals is truly fantastical, even for a legend.
Gradually, the group drifted out of common knowledge. As fewer and fewer things plagued the world, less and less people believed that such things had even existed, and by the time of man's cultivation of fire, the men who worked to make such things possible had passed onto the edges of normal life, a mere shadow, protecting man's continued existence.
The organization they formed out of those days of darkness and despair has gone by many names over the centuries, and the number of men who did work for it have been lost to history. Many of the things they held captive to make the world safe are still held to this day, while others have disappeared off the face of the Earth, either destroyed or escaped, awaiting rediscovery, and hopefully recapture. Regardless of these changes, though, the organization has, from its very conception, operated under one, unchanging creed: They secure, they contain, and they protect.