lit. the old man lost his horse, but it all turned out for the best (idiom); it's an ill wind that blows nobody any good; fig. a blessing in disguise
犹塞翁失马。喻因祸得福。
主谓式；作谓语；同“塞翁失马”
比喻世事的福祸无常，无法一时论定。见塞翁失马条。旧唐书˙卷六十三˙萧瑀传：应遭剖心之祸，翻见太平之日，北叟失马，事亦难常。
《旧唐书·萧瑀传》：“应遭剖心之祸，翻见太平之日，北叟失马，事亦难常。”