The full text is as follows: If you use copper as a mirror, you can straighten your clothes; if you use history as a mirror, you can know the ups and downs; if you use people as a mirror, you can know gains and losses. I always keep these three mirrors to prevent myself from making mistakes. Today, Wei Zheng passed away, and then one mirror died!

From: "Old Book of Tang Wei Zheng Biography", the meaning of these sentences is: if a person uses copper as a mirror, he can wear his clothes and hats properly; if he uses history as a mirror, he can know the rise and fall of the country. The reason; using people as mirrors can help you discover your own rights and wrongs. Once Wei Zheng died, I lost a good mirror.

In the seventeenth year of Tang Zhenguan (AD 643), Wei Zheng, who was outspoken and dared to remonstrate, died of illness. Tang Taizong was very sad and said with tears. This is the highest evaluation of Wei Zheng's life value.

Extended information:

Wei Zheng, courtesy name Xuancheng, was originally from Quyang County, Julu County (now Jinzhou City). Politicians, thinkers, writers and historians of the Sui and Tang Dynasties were called "famous prime ministers of a generation" by later generations for their outspoken advice and assisting Emperor Taizong of the Tang Dynasty in establishing the "Government of Zhenguan".

When he reached the official position of Guanglu Doctor, he was granted the title of Duke of Zheng, with the posthumous title of "Wenzhen". The funeral was simple. In the same year, he entered Lingyan Pavilion. He has written the preface to Sui Shu and the general introduction to Liang Shu, Chen Shu and Qi Shu. Most of his remarks can be found in "Zhenguan Zhengyi". Among them, the most famous one that has been handed down is the "Ten Thoughts on Admonishing Taizong".

Li Shimin, Emperor Taizong of the Tang Dynasty, liked to listen and be kind to all kinds of suggestions. He was well versed in the principle of "listening to both will lead to enlightenment, and partial belief will lead to darkness". Wei Zheng, his minister of direct remonstrance, had gone to dozens of meetings to directly state his faults, and advised Taizong to reflect on himself, be prepared for danger in times of peace, listen to good advice, and choose the good and follow it. After the death of Wei Zheng, Emperor Taizong came to express condolences in person and burst into tears.