A proverb (from Sun Tzu): 'Know your enemy and know yourself, and you will not be imperiled in a hundred battles.' It emphasizes the importance of understanding both your opponent and yourself—applicable to warfare, business, and competition.
新製品を出す前に市場調査を徹底し、敵を知り己を知れば百戦危うからずという考えで準備した。
Before launching the new product, we did thorough market research and prepared with the mindset 'know your enemy and know yourself, and you will not be imperiled in a hundred battles.'
彼はいつも『敵を知り己を知れば百戦危うからず』と言ってから計画を練る。
He always says 'know your enemy and know yourself' before devising a plan.
歴史の授業でこのことわざを扱い、戦略の基本を学んだ。
In history class we covered this proverb and learned the basics of strategy.