Punishment in which the offender suffers what the victim has suffered, exact retribution, as in
Joe believed in an eye for an eye; stealing his client would have to be avenged. This idiom is a quotation from the Bible, which has "Life shall go for life, eye for eye, tooth for tooth" (Deuteronomy 19:21); the idea is contradicted in the New Testament (see
turn the other cheek).