“What is the riddle of the Sphinx? What animal walks on four legs in the morning, two at noon, and three at night?” the sphinx asks Oedipus, the hero of Sophocles’ play Oedipus Rex (426 B.C.). Oedipus answers that it is man (crawling as an infant, walking erect as an adult, and walking with a staff or cane in old age).”
Excerpted from: Corey, Melinda, and George Ochoa. Literature: The New York Public Library Book of Answers. New York: Simon and Schuster, 1993.