lit. water may keep the boat afloat but may also sink it (proverb); fig. the people can support a regime or overturn it; if sth is used properly, one can benefit from it, otherwise it can do harm; things can be double-edged
trad. 水能載舟，亦能覆舟
Also written 水能載舟，亦能覆舟【shuǐ néng zài zhōu , yì néng fù zhōu】