By
魏征 (Wei Zheng, Tang dynasty, 637 CE), presented to Emperor
唐太宗 (Tang Taizong, Li Shimin) during the Zhenguan era. The essay lays out ten things a ruler must reflect on (
十思) — including 'when you see something desirable, think of contentment' (
见可欲则思知足) and 'when you fear arrogance, think of the humility of rivers and seas' (
惧满盈则思江海下百川). Wei Zheng became the archetype of the honest remonstrating minister; Taizong later said, 'With bronze as a mirror one can straighten one's clothes; with history as a mirror one can see rise and fall; with a man as a mirror one can know gain and loss' — referring to Wei Zheng's death.