Once upon a time, there was a little eye farie, who did her job very well. She took pride in her duties of flitting from house to house in the middle of the night, and giving each dutiful child a shiny new quarter in place of each eye he or she would leave under his or her pillow.
The live organs black market was also very pleased with the farie's progress. She had made her quotas for several years straight, and the quality of the goods was second to none.
Eventually however, the world's parents started getting wise to the eye fairy, and the once plentiful supply of child eyes started drying up. The eye fairy's bounty sunk lower and lower until one day she missed her quota.
The market was not a callous bunch. They understood that these things happen. That was why they were very sad when they took the little fairy's eyes so that she could make up her quota. And kicked her in the ribs. And broke one of her wings.
After that, the little eye fairy decided to get out of the eye business. And she lived rather happily until she accidentally walked off a cliff and plummeted to her death.