There was a salt vendor in a village. He used to buy salt from a nearby town. He had a donkey to carry this salt load. There were many streams to be crossed to reach the town.
One day, the vendor was returning after his purchase.
The donkey was loaded with salt bags. While they were crossing a stream, accidentally the donkey slipped and fell into the stream. A lot of salt got dissolved in the water. When the donkey got up the load became very light.
From that day, whenever the vendor returned from town after salt purchase, the donkey began to tumble half-way across one stream or the other. The vendor became suspicious.
Once the vendor purchased bales of cotton and loaded his donkey with bales of cotton. The donkey felt the load to be unusually light. He thought “Today, I am going to tumble and this load is going to become much lighter”.
On their way home, as usual, the donkey tumbled and fell into a stream. But alas! When the donkey tried to get up, the load pulled the donkey down. The cotton had absorbed water and become heavier.
The vendor gave hard beatings to make the donkey get up and walk. From then on, the donkey never tumbled while crossing streams.