From a tale in the Huainanzi (see Chinese 塞翁失馬，焉知非福 / 塞翁失马，焉知非福 (sàiwēng shī mǎ, yānzhī fēi fú) for more). Also compare Korean 새옹지마 (sae'ongjima), from...
varjopuolensa French: toute médaille a son revers Japanese: <span class="searchmatch">塞翁が馬</span> (ja) (saiō ga uma), 人間万事<span class="searchmatch">塞翁が馬</span> (ja) (ningen banji saiō ga uma) Korean: 새옹지마(塞翁之馬) (ko) (sae'ongjima)...
【<span class="searchmatch">塞翁が馬</span>】 [proverb] life goes through ups and downs and is unpredictable...