Plato's four cardinal virtues are prudence, justice, temperance and courage. These virtues are also often translated as wisdom, fairness, restraint (also called moderation) and fortitude.
Plato explains all four virtues in his works "Republic" and "Protagoras." Prudence is a person's ability to judge his own actions as appropriate or inappropriate. Justice is the ability to act with fairness and without bias toward others. Temperance is the ability to act with moderation and self-control. Courage refers to emotional strength and a person's ability to confront his fears. These virtues were later adopted by St. Augustine as the four cardinal virtues of Christianity.