A farmer got so old that he couldn’t work the fields anymore. So he would spend the day just sitting on the porch. His son, still working the farm, would look up from time to time and see his father sitting there.
“He’s of no use any more,” the son thought to himself, “he doesn’t do anything!” One day the son got so frustrated by this, that he built a wood coffin, dragged it over to the porch, and told his father to get in.
Without saying anything, the father climbed inside. After closing the lid, the son dragged the coffin to the edge of the farm where there was a high cliff.
As he approached the drop, he heard a light tapping on the lid from inside the coffin. He opened it up. Still lying there peacefully, the father looked up at his son. “I know you are going to throw me over the cliff, but before you do, may I suggest something?” “What is it?” replied the son. “Throw me over the cliff, if you like,” said the father, “but save this good wood coffin. Your children might need to use it.”
Source: 10 Short Zen Stories
A Useful Life