When it came out of the water, the load became lighter. The ass felt happy. Next day, the ass fell into the river knowingly. The merchant understood its trick. He decided to teach it a lesson.

Next time he loaded the ass with cotton. The ass repeated the trick. The cotton became wet and very heavy. It came out of water with great difficulty. The merchant gave it a good beating. The ass learnt a lesson. It never repeated the trick.

Moral: Cleverness does not pay always.