A rich man in the Qi Kingdom had two foolish sons, yet he doted on them and considered them the apples of his eye.
One day, a man named Ai Zi said to the rich man, "Your sons are ignorant of the world. How will they manage your property after you're gone?"
Hearing this, the rich man grew angry. "Everyone praises my sons for their intelligence and good virtue," he retorted. "What you say is nonsense!"
"Then let's test them," Ai Zi suggested. The rich man agreed.
The father summoned his sons. Ai Zi asked them, "Do you know where rice comes from?"
The elder son smiled confidently. "Anyone with sense knows that. It comes from the kitchen."
The younger son blinked. "You're wrong! It doesn't come from the kitchen. It comes from the bag."
The rich man, red with anger, looked at his sons and shouted, "You fools! Why didn't you ask me if you didn't know? You're both wrong! Rice comes neither from the kitchen nor from the bag. It comes from the barn!"