Once upon a time there lived a farmer in the three kingdoms of China.
This farmer had a son who worked the farm with the help of a horse.
The horse ran away one day.
The local farmers came and said, "How unlucky, your horse ran away."
The farmer said, "Perhaps."
The next day, the horse came back, but was followed by a whole herd.
When the local farmers found out, they said, "You have great luck."
Again, the farmer said, "Perhaps."
Another day passes, and the farmer's son broke his leg while riding some of the new horses.
The local farmers again came, and this time they said, "What bad luck, your son broke his leg."
The farmer repeated, "Perhaps."
On the fourth day, the emperor's army were recruiting for the army and because of the son's broken leg, did not recruit him.
The local farmers this time said, "What great luck, your son did not get recruited."
The farmer again, repeated, "Perhaps."