Each virtue that Plato explains in Republic is connected to the proper work of the State. Virtuous individual is the face of the State- if the citizen is wise, the State will look wise, if the citizen is just the State will be just.
The four virtues, wise, valiant, temperate and just, are needed for the State to be perfect. Plato elucidates how virtues of individual relate to the ideal republic.
First virtue in the State is wisdom. Any knowledge founded among the citizens of the state as a whole considers how a State can best deal with itself and with other States. Different knowledge is spread among the different classes; the knowledge of the craftsmen and the knowledge of true guardians. If craftsmen change their work, and one do a job that he is not educated to do, the ruin of the State is guaranteed.
Second feature of virtues individual is courage. If in war, the citizens are courageous or coward the State will look courageous or cowardly, because the State is judged in fight or war. Solders receive knowledge in music and gymnastic. Education will prepare them for perfection. Their opinion about dangers will be changed by using training and nurture; this according to Plato is courage.
Temperance is the third virtue that the philosopher describes. Ordering and controlling of certain pleasures and desires is the definition of the temperance. "A man being his own master" is the phrase that best characterizes the third virtue- to be master of men's bad features, to learn how to control them. In the State self control is important, because to prosper the ideal republic the better principle has the worse under control. So that, if virtual individual possesses temperance as a virtue the State will be