The ancients said: 'Know yourself and know your enemy, and you'll never lose a battle.'
Tips
history
曰 is the classical Chinese equivalent of 说. It appears in virtually every classical text, especially the Analects (论语) where 子曰 ('The Master said') opens most passages. It's never used in modern spoken Chinese.
mistakes
Don't confuse the character 曰 (yuē, to say) with 日 (rì, sun/day). They look nearly identical — 曰 is wider and shorter, 日 is taller and narrower.
