You can dress with bronze mirrors, you can look at the rise and fall with ancient mirrors, and you can know the gains and losses with men as mirrors.
With copper as a mirror, we can see whether our clothes are neat, with the ancient as a mirror, we can see whether our actions are in line with historical and social development, and with people as a mirror, we can know our gains and losses. Liu Bang, Emperor Taizong of Han Dynasty, Li Shimin and most of the emperors of Qing Dynasty all achieved this, so their rule and the countries they established developed very prosperously, which was a crucial period for the historical development of our country.