Source: Shao's Biography of Old Tang Dynasty and.
The husband can dress up his clothes with copper as a mirror; Taking history as a mirror, we can know the rise and fall; Take people as a mirror, you can know the gains and losses. I have kept these three mirrors in case I pass by. Now Wei Zhi is dead, he died in a mirror!
A person can tell whether his clothes and hat are properly dressed by looking at copper as a mirror. Taking history as a mirror, we can know the reasons for the rise and fall of the country; Looking at people as a mirror, you can find your own right and wrong. I often use these three mirrors to prevent myself from making mistakes. Now that Kevin·Z is dead, I have lost a good mirror.
In the first year of Zhenguan (627), Li Shimin acceded to the throne and appointed Wei Zhi as Zuo Cheng and a college student. Li Shimin was eager to build a prosperous era, and repeatedly summoned Wei Zhi from his bed to inquire about gains and losses. Wei Zhi was outspoken and protested over 200 things.
On one occasion, Wei Zhi remonstrated, and his words were fierce, which hurt the face of Emperor Taizong. When Emperor Taizong returned to the harem, he was furious and said, "I will kill this hillbilly one day!" " To this end, the eldest grandson congratulated Emperor Taizong, saying, "Today, Wei Zhi can call a spade a spade, which shows that he has met a wise monarch. I should congratulate myself. "
Emperor Taizong unconsciously turned anger into joy and treated Wei Zhi as before. Later, when Wei Zhi died, Emperor Taizong said very sadly: "People can take copper as a mirror and clothes as clothes; Take people as a mirror, you can know the gains and losses. Wei Zhi is dead, I lost a mirror! "
Baidu Encyclopedia-Wei Zhi