Sai Weng: frontier fortress old man. The lost horse: the lost horse. How do you know it's not a good thing?
The book Huai Nan Zi Xun says: In ancient times, there was an old man who lost a horse and people came to comfort him. The old man said, "How do you know it's not a good thing?" Later, this horse actually brought back a good horse. Although metaphor suffered temporary losses, it gained benefits. This also means that bad things can be turned into good things.
References:
Yyteng 86- wizard level 4