Literal meaning
frontier (塞) — old man (翁) — lose (失) — horse (马)
Origin
Huainanzi (《淮南子·人间训》). An old man on the northern frontier lost his horse. His neighbors offered sympathy. He said: "Who knows? Maybe it's good fortune." Months later, the horse returned with a fine wild horse beside it. Neighbors congratulated him. He said: "Who knows? Maybe it's bad." His son rode the new horse, fell, and broke his leg. Neighbors offered sympathy. He said: "Who knows?" Soon after, war broke out — all able-bodied young men were drafted, and most died in battle. The son, with his broken leg, was spared. The full proverb is 塞翁失马，焉知非福 — "the old man lost his horse; how do you know it isn't fortune?"
Examples
Usage & nuances
Stoic / consoling tone. Used to suggest patience about an apparent setback. Often invoked when comforting someone — gentle, not preachy.
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