What is the riddle of the Sphinx?
The riddle figures prominently in Greek mythology, and while its exact origins are uncertain, it plays an especially important role in the Sophocles tragedy Oedipus the King. Sophocles never reveals the riddle itself, but the Ancient Greeks said that a Sphinx -- a creature with a head of a woman, the body of a lion, and wings -- guarded/terrorized the city of Thebes, allowing no traveler to pass without solving its riddle. According to a vast compendium of Ancient Greek myths compiled by the Greeks later in the ascendant period of their history, the riddle goes like this:
"What is that which has one voice and yet becomes four-footed and two-footed and three-footed?"
Oedipus famously solved the problem by answering "man," who crawls at the beginning of life, walks during adulthood, and uses a cane in old age. With her puzzle solved, the Sphinx killed herself by throwing herself off a mountain (she really took her riddle seriously!), and Oedipus became king of Thebes, marrying the recently widowed queen, Jocasta.