What did Emperor Taizong use as a mirror?

Tang Taizong took copper as a mirror, history as a mirror and man as a mirror.

Taking man as a mirror means taking Wei Zhi as a mirror.

In the seventeenth year of Zhenguan in Tang Dynasty (AD 643), Wei Zhi, who spoke out and dared to remonstrate, died.

Emperor Taizong was very sad. He said with tears: "husband, with copper as a mirror, you can dress well;" Taking history as a mirror, we can know the rise and fall; Take people as a mirror, you can know the gains and losses. Wei Zhi didn't! I lost a mirror! "