One day, for no reason, the horse of a wise farmer living in ancient China ran away to the nomads across the border. Everyone tried to console him, but he said, “What makes you so sure this isn’t a blessing?” Some months later his horse returned, bringing a splendid nomad stallion. Everyone congratulated him, he said, “What makes you so sure this isn’t a disaster?” Their household was richer by a fine horse, which his son loved to ride. One day he fell and broke his leg. Everyone tried to console him, he said, “What makes you so sure this isn’t a blessing?”

A few months later the nomads invaded a nearby village across the border, and every able-bodied man was called up to take arms. Because the son broke his leg he was excused from military service and had he fought he would have almost certainly died because the regiment that summoned him to action was completely wiped out. Truly, blessing turns to disaster, and disaster to blessing: the changes have no end, nor can the mystery be fathomed.