A poor farmer's horse ran off into the country of the barbarians.  All his neighbors offered their condolences, but his farther said, "How do you know that this isn't good fortune?"

 After a few months the horse returned wtih a barbarian horse of excellent stock. A ll his neighbors offered their congratulations, but his farther said, "How do you know that this isn't a disaster?" 

The two horses bred, and the family became rich in fine horses.  The farmer's son spent much of his time riding them; one day he fell off and broke his hipbone.  All his neighbors offered the farmer their condolences, but his farther said, "How do you know that this isn't good fortune?"

 Another year passed, and the barbarians invaded the frontier.  All the able-bodied young men were conscripted, and nine-tenths of them died in the war.  Thus good fortune can be disaster and vice versa.  Who can tell how events will be transformed?

                   -tao te ching-