Plato thinks that there are four main virtues that is wisdom, courage, temperance and justice; thus, justice is a great virtue, which is everyone doing his work according to his or her nature. He observe that the city divide to three kind of person, some have the virtue of wisdom, they should be rulers; some have courage, guardian; others only suitable as farmer and trader or craftsmen. All people should have temperance and justice, then whole society will harmony and justice will be done. However, to realise the justice, philosopher should be king who has wisdom and able to find the truth. Ordinary people just like in The Republic Book VII, Plato’s imagined in the Cave, people’s necks and legs fettered since childhood, they can only see the shadow but the true light, but they will believer the shadow are true matter because they never see any other true matter, and they do not believe any other explanation. The only one who released (philosopher) can see the sun light and true world, but if he back the Cave and tell those still fettered (ordinary people) what are the truth, nobody will believe him even will think he is out of mind even want to kill him (Socrates was vote by Athens 500 assembly to death for his telling the truth).
Because Plato believe that real political life just like the Cave imagine life, most ordinary people have no wisdom to pursue the truth. Politics is a complicate art which need professional knowledge and wisdom, and only those who have the virtue of wisdom through strict educate with the knowledge of mathematics and geometry and astronomy and dialectical method except gymnastic and music, then it is possible to find the truth. People should in according with philosopher’s instruction to live work together, doing their work according to their nature and talent, then whole society just like a human body, perfect harmony, and this is the Justice. Therefore, Plato against the Athenians democracy, which every citizen could become rulers without special training without necessary knowledge and it is means that the third class to do the first class works which is injustice.
Politics is a science which needs great mind and knowledge as well as wisdom, I quite agree with Plato’s idea that it should not be open to everyone, only those who have enough education and knowledge and wisdom and for public good should be run the government. Citizen have right to choose their leaders do not necessary themselves become leader.