塞翁之馬
변방 노인의 말 — 인생의 화복은 알 수 없다
The frontier elder's horse — fortune and misfortune cannot be foreseen
— Huainanzi, Renjianxun
Horse runs away (misfortune) → returns with finer horses (fortune) → son breaks leg riding (misfortune) → spared from war (fortune). Fortunes chain.