Take copper as a mirror, a husband can dress up, take history as a mirror, know the rise and fall, and take people as a mirror to know the gains and losses.

Vernacular translation: using copper as a mirror? Can organize a person's clothes; Take history as a mirror? You can know the ups and downs in history; Think of others as your own mirror? Know your own gains and losses every day.

Source: Biography of Wei Zhi, an old Tang book.

Extended information source story:

When Wei Zhi died, Emperor Taizong wept bitterly. He said: I have three mirrors (all of them were bronze mirrors before). "With copper as a mirror, I can dress." I can put on his clothes and hat.

"Taking history as a mirror", observing his own administration with history, "knowing the rise and fall", how to make the dynasty prosperous and how to make the dynasty perish, he can observe from history; "Taking the people as a mirror" requires a wise minister to convince him to "know the gains and losses", so that you can understand the gains and losses of all his policies and then correct them.

Emperor Taizong said that he had these three mirrors. When Wei Zhi died, one side was broken. It can also be seen from here that a wise monarch must cherish talents in order to win the trust of these ministers.

Old Tang book:

A total of 200 volumes, including 20 chronicles, 30 memoirs, and biography 150 volumes, formerly known as Tang Shu. After the publication of The Book of the New Tang Dynasty compiled by Song Qi and Ouyang Xiu, it was renamed The Book of the Old Tang Dynasty, which was published in the second year of the Late Jin Dynasty (945).

It has been recorded in the Tang Dynasty. Since the early Tang Dynasty, he has written national history on the basis of factual records, among which Jason Wu and Shu Wei are the most famous. Jason Wu wrote sixty-five volumes (ninety-eight volumes) of the Book of the Tang Dynasty, and Shu Wei supplemented the National History with 112 volumes.

Since then, Liu Fang and others have made sequels. However, Wu Zongshi's records are incomplete, the historical records of later generations have not been compiled, and historical events are lacking. Both the Later Liang Dynasty and the Later Tang Dynasty ordered extensive collection of information about Tang Shi.

References:

Baidu Encyclopedia-Take people as a mirror, and you can see the gains and losses.

References:

Baidu encyclopedia-taking copper as a mirror

References:

Baidu Encyclopedia-Taking History as a Mirror