In ancient times, in a region north of the Great Wall (Saibei), an old man's horse ran away to the land of the northern tribes. His neighbors came to console him, but the old man calmly said, 'This may not necessarily be a misfortune.'

A few days later, the lost horse returned, bringing with it several wild horses. The neighbors congratulated him, but the old man said, 'This may not necessarily be a blessing.'

Indeed, his son, who enjoyed riding, broke his leg while riding one of the new wild horses. The neighbors again offered their sympathies, but the old man stated, 'This may not necessarily be a misfortune.'

Later, a war broke out, and all able-bodied young men were conscripted for battle. Because his son was lame due to his broken leg, he was exempted from military service, thus avoiding the perils of war and saving his life.