A proverb meaning to use others' mistakes or shortcomings as a lesson to improve oneself—an object lesson or 'food for thought'.
先輩の失敗を他山の石として、同じ間違いをしないようにした。
I used my senior's mistake as a lesson so I wouldn't make the same error.
歴史の過ちを他山の石とし、未来に活かすべきだ。
We should take the mistakes of history as lessons and apply them to the future.
彼の批判は耳の痛い話だったが、他山の石として受け止めた。
His criticism was hard to hear, but I accepted it as an object lesson.