The riddle of the Sphinx

In ancient Greek mythology the Sphinx was a creature half-lion half-woman with wings. The legend tells us that she guarded the entrance to Thebes and when Oedipus wished to pass, she told him a riddle which he had to answer on pain of death. Once he solved the riddle, the Sphinx perished and he was lauded by the Thebans for releasing them from their tyranny.