God created the donkey and said to him, "You'll be a donkey and carry everyone's burden and will live for 40 years." The donkey said, "Carrying burdens is OK, but 40 years is too much for me, give me only 30 years." God granted his wish.
God created the dog and said to him, "You will be a dog and look after people's belongings. You'll eat whatever you are given by your masters and live for 40 years ." The dog said, "All conditions are fine, but 40 years is too much for this job. Give me only 20 years." God granted his wish.
God then created the monkey and said to him,
"You will be a monkey and entertain others with your tricks. You will live for 40 years." The monkey said, "God 40 years is too much for me, give me only 30 years." God granted his wish.
God then created man and said to him, "You will be a man and live for 25 years. You will dominate all other creatures." Then the man said, "25 years is too little for a great creature like me. Give me the 10 years that the donkey refused, the 20 years that the dog refused, and the 10 years that the monkey refused." God granted his wish.
From then on, a man lives 25 years as a man, 10 years as a donkey, carrying all the burdens of his house, 20 years as a dog, taking care of his children and eating whatever he is given, and 10 years as a monkey, going from house to house entertaining his grandchildren.