expression, godan verb (-su)
be unable to tell things apart; fumble in the dark
Idiomatic expression literally meaning 'to lead a cow out of the dark', used to describe a situation where one cannot distinguish between things or is acting blindly. Rare and literary.
暗がりから牛を引き出すようなもので、どれが本物かさっぱりわからない。
It's like trying to lead a cow out of the dark; I have no idea which one is genuine.
The exact origin is uncertain; the expression is a fixed idiomatic phrase with a literal image of leading a cow out of darkness, used metaphorically.