塞翁失马 A Blessing in Disguise
In China there's a saying: 塞翁失马,安知非福?(Sàiwēng shī mǎ,ānzhī fēifú?) It could be translated something like: Just like the old frontiersman losing his horse, who knows but that this may be a blessing in disguise.
Anyway this story is a simply told version of the folk tale which gives us this 成语.