Oedipus & The Sphinx; Oedipus encounters a Sphinx which would stop all those who traveled to Thebes and ask them a riddle. If the travelers were unable to answer correctly, they would be killed and eaten by the sphinx; if they were successful, they would be able to continue their journey. The riddle was: "What walks on four feet in the morning, two in the afternoon and three at night?". Oedipus answers: "Man: as an infant, he crawls on all fours; as an adult, he walks on two legs and; in old age, he relies on a walking stick". Oedipus is the first to answer the riddle correctly and, having heard Oedipus' answer, the Sphinx is astounded and inexplicably kills itself by throwing itself into the sea, freeing Thebes.