How a ball of thread became a "clue"
Originally, a "clew" was simply a ball of thread or yarn. Its meaning shifted dramatically thanks to the Greek myth of Theseus, who used a ball of thread to navigate his way out of the Minotaur's labyrinth. Over time, the spelling changed to "clue," and the word evolved from a physical ball of thread into a term for any guide or key to solving a mystery.
The Tangible Origins of Clew
Before it became synonymous with mystery solving, the word existed as the Old English noun cleowen, which later evolved into clew. In its earliest usage, a clew was purely physical: a tightly wound ball of thread, yarn, twine, or wool. The word shared Germanic roots with terms in neighboring languages that described rounded masses or clumps, such as the Dutch kluwen and German Knäuel. For medieval weavers, spinners, and everyday households, winding a clew was a routine chore, creating an organized bundle from which thread could be steadily unspooled without tangling.
The word also found a specialized and durable home in maritime terminology. In sailing, the clew referred to the lower corner of a square sail or the aft lower corner of a fore-and-aft sail, where sheets and tacks were fastened. Sailors spoke of clewing up a sail when hauling the corners up toward the yardarm. This nautical meaning preserved the older spelling clew long after the everyday language began steering the word in an entirely different, metaphorical direction.
Ariadne's Lifeline in the Labyrinth
The bridge between a literal ball of yarn and an abstract guide to solving a puzzle comes directly from classical Greek mythology. In the story of Theseus and the Minotaur, the hero Theseus volunteered to enter the perilous Labyrinth of Crete to slay the half-man, half-bull beast residing at its center. The labyrinth, constructed by the master artisan Daedalus, was designed with such intricate and twisting passageways that anyone who entered was doomed to wander endlessly until killed or starved.
Ariadne, daughter of King Minos, fell in love with Theseus and sought a way to ensure his survival. She provided him with a sword and a clew—a ball of thread. Upon entering the maze, Theseus tied one end of the thread to the entrance and let the ball unwind as he penetrated deeper into the darkness. After killing the Minotaur, he followed the laid-out thread backward, successfully retracing his steps to safety. In Middle English and Early Modern English retellings of the myth, writers consistently used the native English word clew to describe Ariadne's gift.