2 sentences for 知己 (zhī​jǐ — self-knowledge)

1. 知己知彼，百战不殆。

   zhī​jǐ zhī bǐ, bǎi​zhàn​bù​dài.

   Know yourself and know your enemy, and you will never be defeated in a hundred battles.

   Source: Dong Chinese Dictionary

2. 知彼知己，方能百战不殆。

   zhī bǐ zhī​jǐ, fāng néng bǎi​zhàn​bù​dài.

   Know yourself and know your enemy, and you will never be defeated.

   Source: Dong Chinese Dictionary