Geasa

Their physical yearning for each other was nearly as great as their union of poetry, but it was inhibited by a geasa, or taboo, that had been inflicted on Curither by an elderly aesodan, his poetic mentor during the long years of ...

[Y]ears ago I placed a geasa on a baby girl. It was that if she ever saw a three-legged fox, she should follow it. Last year she saw a fox that had three legs, and she followed her geasa. She found a young man sitting by a stream.

The gallant lad did that, too, and triumphed, but, as the Black Goat was passing out, he put upon the boy a geasa to tie up the Jester of the Prince of Darkness. That also the youth did, only to have another geasa put upon him.