know yourself, know your enemy (idiom, from Sunzi's "The Art of War")

a thousand cups of wine is not too much when best friends meet; used to express the joy of drinking and talking with close friends

to know the enemy and know oneself (idiom, from Sunzi's "The Art of War")

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

a true gentleman will sacrifice his life for a friend who understands him, as a woman makes herself beautiful for her sweetheart

knowing the enemy and yourself will get you unscathed through a hundred battles (idiom, from Sunzi's "The Art of War")

To consider someone as a close friend or soulmate; to take into one's confidence.

a close female friend who understands one deeply, often referring to a man's platonic but spiritually intimate female friend

a woman's close platonic male friend or confidant

true friendship transcends physical distance; feeling close in spirit even when far apart