Abstract: The Republic, the representative work of Plato, a Greek philosopher and educator, contains rich educational thoughts, which are still shining today. Plato advocated the establishment of a hierarchical, democratic and harmonious political system on the premise of "the theory of human nature". He strongly advocated education, believing that the primary goal of education is to acquire the virtues of justice and kindness, but education directly serves the country. Plato believes that there is only one important thing that rulers need to do well, that is, education, and training excellent citizens through music and sports. The education of cultivating citizens is only elementary education, and the ultimate goal of education is to cultivate the city-state ruler who combines wisdom and strength-the king of philosophy. Plato's educational thought of pursuing a better life, purifying people's hearts and cultivating virtue still has great reference value today.

Paper Keywords: Plato; Theory of human nature; Educational thought

The Republic, also translated as Country and Republic, is the work of Plato (427- 347 BC), an ancient Greek philosopher and thinker. It is a dialogue with Socrates as the protagonist. The book is divided into ten volumes, discussing various issues such as philosophy, politics, ethics, education, literature and art. The so-called utopia is a country full of justice and virtue inferred by Plato. The core idea of this book is that the king of philosophy should be the ruler of the country, and advocates managing the people with philosophical thoughts. In The Republic, Plato took justice as the theme, developed Socrates' thought of virtue in human nature, and opened the precedent of "knowledge, emotion, will" and "truth, goodness and beauty" in human nature in western history, from which Hume and Kant both started their philosophical theories. In Plato's eyes, only through education can the utopia be realized. Therefore, Rousseau thinks that The Republic is not a treatise on politics, but the best paper on education so far.

1. The influence of Plato's philosophical thoughts on human nature and educational thoughts in The Republic.

1. Social foundation

Plato lived in an era when Athens was in its heyday and decline. For the hegemony of Greece, Athens and Sparta fought the Peloponnesian War for 30 years. The war not only made Athens lose the hegemony of Greece, but also made various social contradictions in Athens explosive. The war dealt a great blow to Athens' economy, losing its leading position in the Greek world, challenging the domestic democratic system, and gradually falling into the hands of nobles. People questioned its ethics and morality, leading to its decline. This made Socrates, Plato and other thinkers with a great sense of responsibility to the polis begin to think about the future of Athens. They envision organizing an ideal city-state, which is just and harmonious.

2. Philosophical basis

Plato is the founder of western objective idealism, and his philosophical system is extensive and profound, which has a great influence on his teaching thought.

(1) idealism. Plato combined Socrates' dialectics with parmenides's "ontology" and put forward "theory of ideas". He believes that the knowledge of "concept" is the real knowledge possessed by human soul, the knowable concept is the basis and cause of sensible things, and sensible things are the derivatives of sensible ideas. One thing has an idea, and all kinds of things have various ideas. Different things make up the world of things, and the whole composed of their ideas is Plato's so-called conceptual world. In his view, the former is a sensible world, while the latter is a knowable world. Plato has demonstrated the theory of two worlds through a series of metaphors, the most famous of which is the Japanese metaphor theory. Plato compared the relationship between the visible world and the sensible world to the relationship between the sun and the earth's creatures, and thought: "The sun not only makes the objects that are seen visible, but also makes them produce, grow and get nutrition, although the sun itself does not produce."

(2) dialectics. Hegel clearly pointed out: "In ancient times, Plato was called the inventor of dialectics. It means that dialectics appeared in the form of free science for the first time in Plato's philosophy, that is, it appeared in an objective form. This statement is indeed correct. " Plato believes that dialectics refers to the method of expressing contradictions between thoughts through conversation, then analyzing and synthesizing them, and then seeking truth. This is a dialectical relationship of unity of opposites. Dialectics is not sophistry, it is an important means to demonstrate ideas. From the dialogue between Socrates and others in The Republic, we can see that dialectics is a way to know the highest state of knowledge and a good way to educate and train. Through dialectics, we can promote the exploration of the relationship between ideas, learn how to construct the concept system, and improve our logical thinking and imagination.

(3) epistemology. Epistemology is Plato's way of acquiring ideas. Plato's epistemology contains three meanings: first, thought cannot rely on human intuition. He believes that everything in the world has an ontology that exists in the conceptual world, that is, "phase". "Image" is a bridge between the ideal world and the real world. Second, epistemology goes through three stages. Plato believes that the mental state of the lowest level of cognition is imagination, so the process of cognition needs to be further deepened, and finally the idea of goodness can be obtained through rational thinking. Third, to understand the concept is to know yourself. Plato believes that only by understanding the external world and thoughts can thoughts rise to a certain height. Ideas are innate, that is, everyone is born with ideas, so he believes that people's understanding of ideas is not acquired learning, but the memory of existing ideas, and the process of this memory is the cognitive process of the external world. Therefore, Plato's epistemology is a transcendental epistemology, through which we can know ourselves and seek the idea of goodness.

As Popper said, Plato's national philosophy can eventually be expanded into a universal philosophy about' everything'. Plato's philosophical thought starts from ethics, aims at pursuing the idea of goodness, and pursues the perfection of human nature and soul. The fundamental problem of national philosophy is the problem of people. Without a profound analysis of human and human nature, politics will lose its correct logical starting point, because society is a society composed of people and people are the main body of society. The philosophical problems of human society inevitably trace back to the problems of human nature.

Second, the' Republic' in the concept of human nature

In the Republic, Socrates discussed "what is justice" and Plato's understanding and reflection on "soul" through dialogue with others. The interpretation of "soul" and the analysis of "justice" are also the interpretation and prospect of "human nature". As R. Waterfield said, "Plato reminds us that when reading this book, we should take many characteristics of the city-state he constructed as the map or key to understand our own inner heart" and "the inner spiritual world of individuals is the concern of this book."

1. The human soul

Orpheus School and Pythagoras School in ancient Greece have long been involved in the issue of soul, and put forward the idea of immortality and reincarnation of soul. Plato inherited and developed this theory in the Republic. In his view, the soul is indecomposable, it is vivid and spontaneous, and it is also rational and pure in the spiritual world. Because it has the desire to pursue the world, it falls to the ground and is enclosed in the body, so it is destined to undergo a purification. The purification of the soul needs education. Plato divided the soul into three levels, namely, reason, passion and desire. In the human soul, rationality is the nature of the soul, the highest principle of the soul, and is connected with ideas; Passion is a natural alliance of rationality and a rational emotion; Desire refers to physical desire, which can be obeyed or deviated from reason. "The soul leaves the body and meditates on the beautiful world of ideas, which is the ultimate goal of life." If you want to protect your soul from those worldly desires, then the only way is to correct your thoughts and stand, conquer your desires with virtue, and purify your mind. Plato's view of soul is essentially about human nature. Theoretical discussion is a kind of pursuit and exploration of people's own spiritual world. He emphasized the control and guidance of reason to passion and desire, and took this role as the basis of virtue formation, thus establishing the ideological line of human nature with rational soul as the core. The state of the soul is still the super-political foundation of the country. The soul molds all virtues, such as courage, wisdom, temperance and justice. Plato's soul theory has enabled mankind to find a feasible way to acquire virtue. He tried to reach the realm of truth, goodness and beauty by first understanding the essence of virtue. Soul theory emphasizes human virtue education, and advocates that people should be kind. It is hoped that through the education of transforming people's souls, citizens will have rational souls, educate and train qualified citizens, and then realize their political ambitions and realize a harmonious ideal kingdom.