It means: a great person on the surface, but evil at heart. It is often used to describe a hypocritical person. It means something like a wolf in sheep's clothing.
The author Han Feizi believes that the real difficulty of lobbying lies in the subjective likes and dislikes of the lobbied object (that is, the monarch), that is, "knowing what he says".
It points out that in order to lobby successfully, we should study the rebellious psychology of the host for propaganda and lobbying, pay attention to the love and hate of the host, and never "shrink" the host.
Extended data
1. Han Fei (about 280-233 BC) was born in Xinzheng (now xinzheng city, Zhengzhou City, Henan Province), the capital of South Korea during the Warring States Period. He is a representative of Legalism, an outstanding thinker, philosopher and essayist. Son of Hanwang, disciple of Xunzi, brother Lisi.
2. The legalist theory founded by Han Feizi provided a theoretical basis for the birth of the first unified and autocratic centralized state in China.
3. Han Fei is a master of legalism, combining Shang Yang's "Fa", Shen Buhai's "Shu" and Shen Dao's "Teacher". Han Fei combines Laozi's dialectics, simple materialism and law. He is the author of Everything is Wrong, with 55 articles,100000 words. It is unique in the prose of pre-Qin philosophers, which shows that Han Fei attaches great importance to materialism and utilitarianism and actively advocates the theory of absolute monarchy, aiming at providing the autocratic monarch with the idea of becoming rich and powerful.
Baidu encyclopedia-Han Fei