The Riddle of the Sphinx
The answer is: a man.
A man is a baby in the morning of his life and he crawls
on four feet.
He is an adult in the noon of his life and he walks on two feet.
But when he is old, in the evening of his life, he walks with a cane,
on three feet.
(This would be true of women, too, but the Greeks told
it about men only).
