Word: clue

A clue is a ball of thread. The word is a variant spelling of clew, Old English cliewen, a wound ball of yarn — and the leap from "ball of yarn" to "hint that solves a mystery" runs through exactly one story. Ariadne gives Theseus a ball of thread before he enters the Labyrinth; he ties one end at the door, unwinds it as he goes, and follows it back out. The maze is unsolvable by reasoning — that…