God created the mule and told him, “You will be mule, working constantly from dusk to dawn, carrying heavy burdens on your back. You will eat grass
and lack intelligence. You will live for 50 years.” The mule answered, “To
live like that for 50 years is too much. Please, give me no more than 20.”
And it was so.
Then God created the dog and told him, “You will hold vigilance over the
dwellings of Man, to whom you will be his greatest companion. You will eat
his table scraps and live for 25 years.” The dog responded, “Lord, to live 25 years like a dog is too much. Please, no more than 10 years.” And it was so.

God then created the monkey and told him, “You are monkey. You shall swing
from tree to tree, acting like an idiot. You will be funny, and you shall live for 20 years.” The monkey replied, “Lord, to live 20 years as the clown of the world is too much. Please, Lord, give me no than 10 years.” And it was so.

Finally, God created Man and told him, “You are Man, the only rational being
that walks the earth. You will use your intelligence to have mastery over the creatures of the world. You will dominate the earth and live for 20 years.” And the man responded, “Lord, to be Man for only 20 years is too little. Please, Lord, give me the 20 years the mule refused, the 15 years the dog refused, and the 10 years the monkey rejected.” And it was so.

And so God made Man to live 20 years as a man, then marry and live 20 years
as a mule, carrying heavy burdens on his back. Then, he is to have children and live 15 years as a dog, guarding his house and eating the leftovers after they empty the pantry; then to live 10 years as a monkey, acting like an idiot to amuse his grandchildren. And it is so.