《史记·七十列传·平原君虞卿列传》
秦国即使善于进攻，也不能轻易地夺取六个县；赵国即使不能防守，终归也不会丧失六座城。
秦虽善攻，不能取六县；赵虽不能守，终不失六城。
Even if the State of Qin is good at attacking, it cannot easily seize six counties; even if the State of Zhao cannot defend, it will not lose six cities.