with one's own body; by one's own action; through one's own experience; firsthand
with this I (formal); by this I (formal)
fight fire with fire; set a thief to catch a thief; fight one evil with another
hard to replace (with other person)
to control foreigners by foreigners; to play one barbarian state against another
birds of a feather flock together
to make a personal judgment on a problem with little insight; (lit.) to look at the sky through a tube (Zhuangzi)
to lose an argument despite being in the right; to have the right on one's side, yet succumb to another