The theme of the story is that you will get out what you put in.
In this story, a group of villagers finds a hole that seemingly has no bottom while they are trying to repair a shrine after a typhoon.
They do not know what to make of the hole, and someone finally yells into it. When there is no response, he picks up a pebble.
"You might bring down a curse on us. Lay off," warned an old man, but the younger one energetically threw the pebble in.
Here is the moment of truth. They are doomed from this point on. Whatever goes into the hole is going to come out, but they do not know that yet. So they continue to throw things in the hole without thinking about the consequences. They use the hole as a depository for all of their trash—an endless landfall. Yet what goes in must go out.
Then, as he resumed his former position, from the direction where the voice had come, a small pebble skimmed by him and fell on past.
The man does not notice. The old man was right.
This story is an example of an ecological cautionary tale. We can do whatever we want to the environment now, but we do not really know what the long-term effects will be. We may not see the damage we are doing until much later, but the damage will still be there and it will come back to haunt us.