Plato (Greek: π λ? Plato is an important thinker in ancient Greece and one of the greatest thinkers and philosophers in western culture. He has been to Egypt, Asia Minor and southern Italy to engage in political activities in an attempt to realize his noble political ideal. In philosophy, the first huge objective idealism system in the history of European philosophy was established. In 387 BC, an academy was established near Agal Demi Gymnasium, where he taught for 40 years until his death. He wrote a lot in his life, and his teaching thoughts were mainly concentrated in the Republic and the Law. Plato was the founder of objective idealism philosophy in ancient Greece, and initiated the psychological thought of idealism. His book The Republic contains the earliest prototype of classification in the history of European psychology: the dichotomy of knowledge, emotion and meaning.