Socrates basically does not have his own philosophical system. He was the first person to pull philosophy from heaven to earth (natural philosophers before him only paid attention to the outside world, while Socrates paid attention to people's hearts)-"Know yourself". His important propositions include "no one intentionally does evil" and "the country is a capitalized person", and his pioneering method is "midwifery".

Plato's most important theory is idealism, which holds that there is an ideal world of truth, goodness and beauty outside the real world, and everything in the world exists because of ideas. He used the famous "cave metaphor" to illustrate the ideological theory, and also emphasized the responsibility of intellectuals. His book Dialogue Collection is written in the form of dialogue and is well worth reading.

Aristotle discovered the defects of Plato's theory of ideas and tried to replace it with the theory of "entity", but he himself was confused when distinguishing the first entity from the second entity. He also put forward the famous "four causes theory" to explain the movement of the material world. His aesthetics and political thoughts both advocate the "golden mean" (of course, he doesn't know Confucius, but both advocate that the "golden mean" is the best. His system is huge and he is the founder of subject classification. It's almost endless.