A boy and a girl were playing together. The boy had a collection of marbles. The girl had some sweets with her. The boy told the girl that he will give her all his marbles in exchange for her sweets. The girl agreed.
The boy kept the biggest and the most beautiful marble aside and gave the rest to the girl. The girl gave him all her sweets as she had promised.
That night, the girl slept peacefully. But the boy couldn't sleep as he kept wondering if the girl had hidden some sweets from him the way he had hidden his best marble.
This is one of the best forwards I have received for some time now and the beauty of it lies in the simplicity of putting forward an extremely important point.