[acidburnNSA]

I was taught this by a Chinese culture coach. She said it more like:

Man's horse runs away: aww Horse returns, brings new wild horse: yay new horse Son riding wild horse breaks leg: aww War comes and takes able-bodied men: yay get to live

[nneonneo]

This story gives rise to the idiom “塞翁失马，焉知非福” - the old man lost his horse, but it turned out to be a blessing.