FOUR JOLLY MEN

Four jolly men sat down to play,

And played all night 'til break of day;

They played for money and not for fun,

With separate scores for everyone.

Yet when they came to square accounts,

They all had made quite fair amounts;

Can you now this paradox explain,

If no one lost, how could all gain?

Answer:

They were four musicians.

Credit:
Riddle ascribed to Sir Isaac Newton