Source: "Common Sense Lessons" from Huai Nan Zi: "There was a man who lived by the Great Wall. His horse ran off to the barbarian lands. People all sympathized, but he said, 'Who knows? This may end in good luck.'
出處：《淮南子．人間訓》：近塞上之人，有善術者，馬無故亡而入胡，人皆吊之，其父曰：「此何遽不為福乎？」