Plato, for his part, advocated that only virtue is purely good, that goodness is essential to well-being, that evil should not be returned for evil, that most men commit wrongness out of ignorance, and that evil is wrongness committed on purpose.
Plato defined the Four Virtues as being Temperance, Prudence, Courage, and Justice. It is these four virtues that make up core of ethics and is the key to living an excellent and rewarding life.
Temperance
Temperance is the first Virtue, and no other Virtue can be sustained without Temperance. Temperance is, in essence, the practice of moderation. It does not dictate what can and cannot be done, only that things should be done with restraint and self-control. This applies most especially to eating, drinking, accumulating wealth or material goods, and sexual intercourse. As long as Temperance is exercised in relation to these and other activities, one is considered to be temperate. Abstinence from these activities is asceticism (with abstinence from food and drink being either fasting, or a restricted diet such as vegetarianism), and while good, asceticism is not consider terribly Prudent.
Prudence
Prudence is therefore the next Virtue, which is the exercise of wisdom, or is simply synonymous with wisdom. Prudence does not dictate what actions can or should be taken, or what is right or wrong. It only dictates that the outcome of any circumstance must be weighed and considered, using good judgment, common sense, and reason, to determine any course of action. Harming or killing another may seem wrong, but when circumstances show that a greater wrong may result from not harming or killing (i.e., as an act of self-defense, or to defend another, or to go to war to defined a nation), then that act would be prudent. Theft is an illegal act by the laws of all nations, however, Prudence dictates that if one steals food to survive, if it is the only way to survive, then the act is neither evil nor wrong, but prudent. Prudence is the act of weighing consequences and arriving at the solution that does the most good or least harm. Even if some harm is committed in the act, if the alternative would have caused more harm, then the action was a prudent choice.
Courage
Courage, or Fortitude, is the ability to face danger, difficulty, or suffering and the strength to persevere even under dire circumstances. The Virtue of Courage is not blind bravado, but rather, is the strength to implement and sustain a choice made in accordance to the other Virtues (Temperance, Prudence, and Justice). It is not enough to desire to be virtuous, for it takes courage to be virtuous. Courage is what gives strength to live a temperate life, to make prudence choices, and to exercise fair justice. When faced with a difficult decision, such as to save many lives by giving your own life, the prudent choice is to sacrifice oneself to save the many, but it takes Courage to commit to this action. Without Courage, no other Virtue can be realized.
Justice
Justice is the final Virtue, and naturally arises if and when all other Virtues are observed and honored accordingly. The person who Courageously lives a Prudent and Temperate life, will act Justly in all that he or she does. Justice is the act of dealing fairly with another in accordance to what they deserve. While ambiguous, and quite literally "a judgment call", Justice also acts upon the other three virtues. When making a Prudent choice, the virtuous person would also have to exercise Justice: the choice between saving a murderer from a burning building or saving a small child is quite clear; however, the choice between saving an artist or a physician is less clear. Nevertheless, Justice dictates the answer, even if it is a cold answer: save the physician, for the physician can help others who may be injured, thus serving the greater good. Not coincidentally, it is also more Prudent to save the physician, for the Just choice is of necessity the Prudent choice as well (that is, for the greater good or lesser ill). Justice can also be exercised when allotting reward or punishment to an individual. A reward or punishment justly made will never out weigh the accomplishment or crime, but will match it with a fair and equal value. Such a judgment must be exercised with Prudence and Temperance, and enforced with Courage.
The Cardinal Virtues
Together, these four Virtues, called the Cardinal Virtues, make up the core of ethics and morality. Aristotle and later philosophers expanded upon these virtues, breaking them down and further developing their definition. However, ethics and morality are not directly related to law, which is used strictly to sustain civil order. However, just laws are those laws which are based on ethical principles, and which serve the greater good. Unjust laws are those that conflict with ethical principles, and that are not for the greater good, but favor the selfish goals of a ruler or the ruling body. A people or persons are in the moral right to rise up against unjust laws, for it is most prudent to do so in order to serve the greater good.