I had no clue all along.

Last week, I came to the delightful word "clew," a ball of thread and, in
particular, that which the Cretan princess Ariadne gave to Theseus before he
went into the labyrinth to fight the Minotaur. Without it, the hero could not
have got out even after he had slain the monster.

The more amazing word was "clue," however, which I met a couple of pages later in
the dictionary. It has its origin in clew. How fitting!