You’ve probably heard the story of Theseus and the Minotaur: how the young hero wound his way through a fiendish labyrinth, to slay the fearsome beast hidden in its confines.
But do you recall how Theseus escaped from the maze, when others had been trapped there forever? He fastened one end of a ball of thread to the labyrinth’s entrance and used it to trace his route from the beginning, following its path on his return.