also: てきをしりおのれをしらばひゃくせんあやうからず
expression
know your enemy and know yourself, and you will not fear a hundred battles
Proverb derived from Sun Tzu's Art of War. Emphasizes that thorough knowledge of both the opponent and oneself ensures victory.
「敵を知り己を知れば百戦危うからず」という言葉は、孫子の兵法に由来する。
The saying 'Know your enemy and know yourself, and you will not fear a hundred battles' originates from Sun Tzu's Art of War.
From Sun Tzu's Art of War (孫子). The Japanese is a classical-style rendering of the Chinese original.