A sphinx is a mythical creature of Egyptian origin with the body of a lion and the head of a woman. The sphinx was brought from Egypt into Greek art and mythology, where she became a monster who guarded the entrance to the city of Thebes. She asked a riddle to travellers before she would allow them to pass; if they answered wrongly, they would be killed. Oedipus solved the riddle, after which the Sphinx either threw herself from a cliff or devoured herself. According to later accounts, the riddle of the Sphinx was:
“Which creature goes on four legs in the morning, on two at mid-day, and three in the evening?”
The answer is man – he crawls on four legs as a baby, walks upright as an adult, and uses a cane as an old man.