明めい鏡きょうも裏うらを照てらさず

expression

anyone can make a mistake; even Homer nods

Proverb meaning that even the wisest or most capable person can err. The literal image is that even a polished mirror cannot reflect its own back side.

• 彼かれほどの専せん門もん家かでも間ま違ちがえることがある。明めい鏡きょうも裏うらを照てらさずだ。

  Even an expert like him can make mistakes. Even a polished mirror cannot reflect its reverse side.