What is Plato's Theory of Cardinal Virtues?

Plato's 4 Cardinal Virtues:

• Wisdom (Sophia): Associated with Rational part of soul and Philosopher Kings.
• Courage (Andreia): Associated with Spirited part of soul and Warrior/Guardian class.
• Temperance/Moderation (Sophrosyne): Associated with Appetitive part of soul and Producer class.
• Justice (Dikaiosyne): Harmony among the three parts of soul and classes of society.