bright mirror; clear mirror; Der Spiegel high; tall hang; suspend trad. (明鏡高懸) 明鏡 高 懸 simp. (明镜高悬) 明镜 高 悬 Literally: “a bright mirror hung high”.
According to Miscellaneous Records of the Western Capital, Qin Shi Huang, the first emperor of the Qin Dynasty, had a mirror which could show the good or evil of a person. This gave rise to the phrase.