The honest and upright way of living, as in He led a wild life when he was young, but he's been on the straight and narrow for some years . This expression is widely though to come from confusion of straight, "not crooked," with strait, "narrow," owing to a misinterpretation of a passage from the New Testament: "Strait is the gate, and narrow is the way, which leadeth unto life" (Matthew 7:14). The current phrase dates only from the first half of the 1800s.