On the first day, Zeus created the dog and said:
So Zeus agreed.
'Sit all day by the door of your house and bark at anyone who comes in or walks past. For this, I will give you a life span of twenty years.' The dog said: 'That's a long time to be barking. How about only ten years and I'll give you back the other ten?'
On the second day, Zeus created the monkey and said:
'Entertain people, do tricks, and make them laugh. For this, I'll give you a twenty-year life span.' The monkey said: 'Monkey tricks for twenty years? That's a pretty long time to perform. How about I give you back ten like the Dog did?'
And Zeus agreed.
On the third day, Zeus created the cow and said:
'You must go into the field with the farmer all day long and suffer under the sun, have calves and give milk to support the farmer's family. For this, I will give you a life span of sixty years.' The cow said: 'That's kind of a tough life you want me to live for sixty years. How about twenty and I'll give back the other forty?'
And Zeus agreed again.
On the fourth day, Zeus created man and said:
'Eat, sleep, play, marry and enjoy your life. For this, I'll give you twenty years.'
But man said: 'Only twenty years? Could you possibly give me my twenty, the forty the cow gave back, the ten the monkey gave back, and the ten the dog gave back; that makes eighty, okay?'
'Okay,' said Zeus, 'You asked for it.'
So that is why for our first twenty years we eat, sleep, play and enjoy ourselves. For the next forty years we slave in the sun to support our family. For the next ten years we do monkey tricks to entertain the grandchildren. And for the last ten years we sit on the front porch and bark at everyone.