《史记·七十列传·苏秦列传》
现在，秦国攻打齐国的情况就不同了，秦国背靠着韩、魏的土地，要经过卫国阳晋的要道，穿过齐国亢父的险塞，战车不能并驶，战马不能并行，只要有一百人守在险要之处，就是有一千人也不敢通过，即使秦国军队想要深入，就像狼一样疑虑重重，时常回顾，生怕韩、魏在后面暗算它。
今秦之攻齐则不然。倍韩、魏之地，过卫阳晋之道，径乎亢父之险，车不得方轨，骑不得比行，百人守险，千人不敢过也。秦虽欲深入，则狼顾，恐韩、魏之议其後也。
Now, the situation of the State of Qin attacking Qi states is different. With its back against the lands of Han and Wei, the State of Qin had to pass though the important road of Yangjin in Wei state and the dangerous narrow pass of Kangfu in Qi state. War chariots could not drive abreast, nor could war horses run side by side. Even if a hundred men were to guard the dangerous pass, even if there were a thousand men, they would not dare to pass. Even if the State of Qin's troops wanted to advance deep into the land, they would be as irresolute and suspicious as wolves, looking back every now and then, afraid that Han and Wei would attack them from behind.