Socrates: Before Socrates, Greek philosophy mainly studied the origin of the universe and what the world was made of, and was later called "natural philosophy". Socrates thinks that re-studying these problems has no practical significance for saving the country. Out of concern for the fate of the country and people, he turned to study human beings themselves, that is, to study human ethical issues, such as what is justice and what is injustice; What is courage and what is cowardice; What is honesty and what is hypocrisy; What is wisdom and how knowledge is acquired; What is a country, what qualities a person should have to govern a country well, how to cultivate talents for governing the country and so on. Later generations called Socrates' philosophy "ethical philosophy". He opened up a new field of philosophical research and made philosophy "return from heaven to earth", which is of great significance in the history of philosophy.

Plato: Seeking Eternity in a Short Life

Love is the joy brought by beauty, the miracle created by wisdom and the surprise given by the gods. People who lack love long for love, while those who have love cherish it.

Love, only affection, can make people dare to give their lives for the people they love; This can be done not only by men, but also by women.

Respect for people should not be superior to respect for truth.

Time has taken everything away, and it will change your name, appearance, personality and destiny in the years.

Procrastination is the best way to suppress anger.

Early education should be a kind of entertainment, so it is easier to find a natural hobby. Aristotle divided science into:

(1) theoretical science (mathematics, natural science and the first philosophy later called metaphysics);

(2) Practical science (ethics, politics, economics, strategy and decoration);

(3) The science of creation, namely poetics.