Getting Out of Work Makes Work Harder/ 陳雅琳

This story was about a donkey avoided work which makes work harder. 

There was an old salt seller. He took heavy bag of salt to a market. He put them on his donkey. The donkey didn’t like this. One day, the donkey fell into the stream. That made some of the salt dissolved. However, now they were not heavy. This made the donkey happy. The donkey started to use this trick every day. The seller was losing a lot of salt. So, he filled a bag with cotton. He put it on the donkey. When they got to the stream, the donkey fell into it. The cotton became wet and very heavy. It was hard to carry, but the donkey had to do it anyway.

I had read the story when I was young. I though the donkey was stupid. Why did the donkey do that?