Jim Wilkins wrote:

Good. Try your well-oiled brain on the Riddle of the Sphinx:

What walks on four legs in the morning, two legs at noon and three in
the afternoon?

A person: crawls on all fours, walks upright, uses a stick.

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"I'm a doctor, not a mechanic." Dr Leonard McCoy
"I'm a mechanic, not a doctor." Volker Borchert