What was the purpose of riddle Sphinx in

The purpose of the Sphinx's riddle in Greek mythology was to guard the city of Thebes. According to the legend, anyone who failed to answer the riddle would be devoured by the Sphinx, a creature with a lion's body, a woman's head, and wings. The riddle was as follows: "What creature walks on four legs in the morning, two legs at noon, and three legs in the evening?" The answer was "human," as humans crawl on four legs as infants, walk upright as adults, and use a cane or walking stick in old age.