The Old Man on the Frontier Lost His Horse, Blessing or Bane? 塞翁失马,焉知非福？

Once upon a time, there was a man who was well versed in the practices of Daoism, lived in the frontier zone. His horse, for no reason at all, got into the territory of the frontier tribes. Everyone was sad for him.‘Who knows, this may turn out to be a blessing,’ said his father.

After a few months, his horse came back on its own together with a fine horse. Everyone congratulated him.

‘Who knows, this may turn out to be a cause of misfortune,’ said his father.

Since the man was well-off and kept good horses, he became fond of riding and eventually broke his thigh bone falling from a horse. Everyone was sad for him.

‘Who knows, this may turn out to be a blessing,’ said his father.

One year later, the frontier tribes started a big invasion of the border regions. All able-bodied young men took up arms and fought against the invaders, and as a result, around the border nine out of ten men died. But just because he was lame, the man and his father were both spared.
Therefore, whether good fortune would turn into calamity, and calamity would turn into good fortune, these changes cannot be predicted. They are indeed unfathomable.
.
近塞上之人，有善术者。马无故亡而入胡，人皆吊之。
其父曰：“此何遽不为福乎？”
居数月，其马将胡骏马而归，人皆贺之。
其父曰：“此何遽不能为祸乎？”
家富良马，其子好骑，堕而折其髀（读音bi四声，股，大腿），人皆吊之。
其父曰：“此何遽不为福乎？”
居一年，胡人大入塞，丁壮者引弦而战，近塞之人，死者十九，此独以跛之故，父子相保。
故福之为祸，祸之为福，化不可极，深不可测也。
（淮南子·人间训）