During the Warring States Period, there was an old man who raised many horses. One day, he lost one of his horses. After hearing about the incident, his neighbors all came to comfort him.

The old man smiled and said, "It's nothing. Perhaps it will bring me good fortune." A few days later, the lost horse came back and brought back another fine horse. Learning about this, the neighbors all came to congratulate him. However, the old man was not at all happy. "It is not necessarily a good thing. Perhaps this will soon turn out to be a cause of misfortune," he said worriedly.

One day, his son went out for a ride on the fine new horse. He accidentally fell from the horse and broke his leg. "Perhaps this will soon turn out to be a blessing," said the old man. A few days later, his son avoided getting drafted for war because of his broken leg.

The idiom "塞翁失马,焉知非福 sài wēng shī mǎ, yān zhī fēi fú" refers to a loss that may turn out to be a gain and vice versa.