A man entered this fairy knowe near Killin and found inside a woman making porridge. The dish boiled so fiercely that a spark from the porridge flew and struck him in the eye. He saw the fairies ever after with that eye.
That is not the end of the story, as told by John Campbell in Superstitions of the HIghlands and Islands of Scotland. One day, at St. Fillan market at Killin, the man saw a great number of fairies riding about the market on white horses. Meeting one whom he recognized, he commented on how many of the fairies were there. The fairy asked in return which eye he saw him with, and, on being told, put it out. This is standard fairy procedure with humans who gain the ability to see them, usually by using 'fairy ointment,' meant only for the eyes of fairy children.