Listen to this articlechúnwánɡ-chǐhán 唇亡齿寒
Once the Lips Are Gone, the Teeth Will Feel Cold.
嘴唇没有了，牙齿就会感到寒冷。比喻相互间关系密切，相互依存，有共同的利害关系。据《左传·僖公五年》载，晋国向虞国借道，以便攻打虞国的邻国虢国。虞国的大夫宫之奇向国君进谏说：虢是虞的屏障，虢亡，虞必随之而亡，虞和虢是唇亡齿寒的关系。这实际反映华夏民族自古以来重视邻国关系和与邻友善、务实的地缘政治思想。
When two things are interdependent, the fall of one will endanger the other. According to the early chronicle Zuo’s Commentary on The Spring and Autumn Annals, when the State of Jin wanted to march through the State of Yu in order to attack Yu’s neighbor, the State of Guo. Gongzhiqi, a minister of Yu, remonstrated with his ruler, saying, “Guo provides a protective shield for Yu. If Guo falls, Yu will soon follow. The relationship between Yu and Guo is like that between lips and teeth.” This shows that since ancient times the Chinese nation has been keen to maintain friendly ties with neighboring countries. It represents pragmatic geopolitical thinking of maintaining amity with close neighbors.
引例 Citation：
◎且赵之于齐楚，扞蔽也，犹齿之有唇也，唇亡则齿寒。今日亡赵，明日患及齐楚。（《史记·田敬仲完世家》）
（而且赵国对于齐、楚两国来说，就是屏障，就像牙齿有嘴唇一样。嘴唇没有了，牙齿就会感觉寒冷。今天[秦国]灭了赵国，明天就会祸及齐国和楚国。）
To the states of Qi and Chu, the State of Zhao serves as a protective shield, just like the lips protecting the teeth. Once the lips are gone, the teeth will feel cold. If Zhao is defeated by the State of Qin today, the same fate will befall Qi and Chu tomorrow. (Records of the Historian)
