《资治通鉴·周纪·周纪三》
以拥有万辆战车的国家，进攻另一个同样拥有万辆战车的大国，五十天就攻克了，单单凭借人力是做不到的；不兼并燕国，一定会遭到天谴。
以万乘之国伐万乘之国，五旬而举之，人力不至于此；不取，必有天殃。
To attack another powerful country with ten thousand war chariots with a country that also has ten thousand war chariots, it is impossible to conquer it in 50 days solely through human effort; if you do not annex Yan, you will definitely be punished by heaven.