The mystery of the sphinx

Along long time ago, the city of Thebes was guarded by a sphinx, a creature with the head of a woman, the body of a lion and the wings of an eagle.

She asked the same riddle to every passer-by and when they could not answer, she consumed them.

'What being,' the sphinx asked Oedipus, when he came upon her, 'has four legs in the morning, two at midday and three in the evening?'

'Man,' answered Oedipus. 'As a child he crawls on all fours, in his prime he walks on two legs and when he is old he leans on a stick.'