In 399 BC, Socrates was tried and sentenced to death. Plato was completely disappointed with the existing regime, so he began to travel around Italy, Sicily, Egypt, Cyrene and other places for knowledge. At the age of forty (about 387 BC), I returned to Athens after my trip and was in Athens.

Akkadmi, the holy city in the northwest suburb outside Athens.

Established its own school-Academie, which became one of the earliest well-organized institutions of higher learning in western civilization, hence the name of the later academic institution and the predecessor of the developed universities in the Middle Ages. Akkadmi is named after its location, which used to be the residence of the legendary Greek hero demos. The college existed for more than 900 years until it was closed by Justinian the Great in 529 AD. The college is greatly influenced by Pythagoras, and its curriculum is similar to the traditional topics of Pythagoras school, including arithmetic, geometry, astronomy and acoustics. It is said that Plato erected a monument at the entrance of the academy: "Those who don't know geometry are not allowed to enter". The college has trained many intellectuals, the most outstanding of which is Aristotle.