People can dress up their clothes with copper as a mirror; Looking at the past as a mirror, we can see the rise and fall; Take people as a mirror, you can know the gains and losses. Which king's famous saying is this? What he said was surprising. Li Shimin, Emperor Taizong, was talking about his minister Wei Zhi.

Encouraging ministers to give advice, he is also willing to accept advice and has the courage to mend his ways, so he is really good at making suggestions. This is not only the biggest highlight of Emperor Taizong, but also the foundation of his life's virtue. Without this, he was only a successful founding monarch at best, just like Emperor Gaozu Liu Bang, Emperor Guangwu Liu Xiu, Song Taizu Zhao Kuangyin and others.

After the death of Wei Zhi, a famous minister, Emperor Taizong mourned him and said: "People can take copper as a mirror, dress properly, take history as a mirror, see the ups and downs (ups and downs), and take people as a mirror to know the gains and losses; Wei Zhi didn't, I lost a mirror. " This is a famous saying widely read by later generations, but there are some inaccuracies here. In fact, Emperor Taizong did not take Wei Zhi as a mirror to examine his own gains and losses. The mirror he referred to was actually Yang Guang, the emperor of Yang Di. Wei Zhi is just a good supervisor. He has a good eye and dares to correct the mistakes of Emperor Taizong.