A proverb meaning that good and bad fortunes are unpredictable — what seems good may turn bad and vice versa.
大学に落ちて落ち込んだが、塞翁が馬だと思って別の道を探すことにした。
I was depressed after failing to get into university, but thinking '塞翁が馬', I decided to look for another path.
仕事が急に忙しくなったのは大変だが、塞翁が馬とも言える。
It's tough that work suddenly got busy, but one could say '塞翁が馬'.
人生は塞翁が馬。今の不運が将来の幸運につながることもある。
Life is '塞翁が馬' — current misfortune can sometimes lead to future good luck.