A salt seller used to carry the salt bag on his donkey to the market every day. On the way they had to cross a stream. One day the donkey suddenly tumbled down the stream and the salt bag also fell into the water. The salt dissolved in the water and hence the bag became very light to carry. The donkey was happy.
But the dampened cotton became very heavy to carry and it suffered much. It learnt a lesson. Afterwards it did not play the trick and the seller was happy.