Chinese Idiom：前车之鉴 (qián chē zhī jiàn)

During the Western Han dynasty (xī hàn西汉), there lived in Loyang a man named Jia Yi. Jia Yi was very knowledgeable , and even the emperor engaged him as a teacher. One day, he was teaching the emperor about the proper way to govern a country. He said, "During the Ch'in dynasty, there was an evil minister named Jau Gau, who was the teacher of Hu Hai, the emperor's second son. He ofter taught Hu Hai how to destroy one's political opponents, and often talked of how to execute prisoners."

"After his father's death, Hu Hai became emperor. On the second day of his reign, he began to kill people, and would not listen to those who tried to give him advice. In reality, Hu Hai was not a bad person, but in the end, he was overthrown."

Jia Yi continued, "Knowing the mistake made by our elders, we should be careful not to make the same ones ourselves. It's the same way as if we are out driving and see that the poor road ahead of us has caused a cart to overturn. We should learn from this, and not take the same road."

Thus, "A Warning Taken From the Overturned Cart Ahead" means seeing the mistake that someone else has made, and not making the same mistake ourselves.

西汉时候，洛阳地方有个人名叫贾谊。他是个很有学问的人，连皇帝都请他当老师。有一次他给皇帝上课，讲治国的道理，他说：“秦朝有个奸臣叫赵高，是秦始皇第二个儿子胡亥的老师，常常告诉胡亥消灭政敌的方法，也常说怎么样处决囚犯的事情。”

“秦始皇死后，胡亥做了皇帝，第二天就开始杀人。有人劝他，他就认为那个人说他不好，简直不像皇帝。其实胡亥的本性并不坏，后来他就被推翻了。”

贾谊又说：“我们知道了以前的人犯的错误，就应该别再犯那样的错。就好比看见前面的路不好，车翻了，就不要再走那条路。”

前车之鉴 (qián chē zhī jiàn)
【翻译】A Warning Taken From the Overturned Cart Ahead.
【释义】鉴：镜子，为教训。前面车子翻倒的教训。比喻先前的失败，可以做为以后的教训。
【例句】有了上一次的前车之鉴，他做事情更加细心了。
【近义词】前车可鉴、殷鉴不远
【反义词】重蹈覆辙