Socrates, as recorded in Plato's dialogues, is customarily regarded as the father of Western ethics. He asserted that people will naturally do what is good provided that they know what is right, and that evil or bad actions are purely the result of ignorance: "There is only one good, knowledge, and one evil, ignorance". He equated knowledge and wisdom with self-awareness (meaning to be aware of every fact relevant to a person's existence) and virtue and happiness. So, in essence, he considered self-knowledge and self-awareness to be the essential good, because the truly wise (i.e. self-aware) person will know what is right, do what is good, and therefore be happy.
According to Aristotle, "Nature does nothing in vain", so it is only when a person acts in accordance with their nature and thereby realizes their full potential, that they will do good and therefore be content in life. He held that self-realization (the awareness of one's nature and the development of one's talents) is the surest path to happiness, which is the ultimate goal, all other things (such as civic life or wealth) being merely means to an end. He encouraged moderation in all things, the extremes being degraded and immoral, (e.g. courage is the moderate virtue between the extremes of cowardice and recklessness), and held that Man should not simply live, but live well with conduct governed by moderate virtue. Virtue, for Aristotle, denotes doing the right thing to the right person at the right time to the proper extent in the correct fashion and for the right reason - something of a tall order.
Cynicism is an ancient doctrine best exemplified by the Greek philosopher Diogenes of Sinope, who lived in a tub on the streets of Athens. He taught that a life lived according to Nature was better than one that conformed to convention, and that a simple life is essential to virtue and happiness. As a moral teacher, Diogenes emphasized detachment from many of those things conventionally considered "good".
Hedonism posits that the principal ethic is maximizing pleasure and minimizing pain. This may range from those advocating self-gratification regardless of the pain and expense to others and with no thought for the future (Cyrenaic Hedonism), to those who believe that the most ethical pursuit maximizes pleasure and happiness for the most people. Somewhere in the middle of this continuum, Epicureanism observed that indiscriminate indulgence sometimes results in negative consequences, such as pain and fear, which are to be avoided.
The Stoic philosopher Epictetus posited that the greatest good was contentment, serenity and peace of mind, which can be achieved by self-mastery over one's desires and emotions, and freedom from material attachments. In particular, sex and sexual desire are to be avoided as the greatest threat to the integrity and equilibrium of a man's mind. According to Epictetus, difficult problems in life should not be avoided, but rather embraced as spiritual exercises needed for the health of the spirit.
Pyrrho, the founding figure of Pyrrhonian Skepticism, taught that one cannot rationally decide between what is good and what is bad although, generally speaking, self-interest is the primary motive of human behavior, and he was disinclined to rely upon sincerity, virtue or Altruism as motivations.
Humanism, with its emphasis on the dignity and worth of all people and their ability to determine right and wrong purely by appeal to universal human qualities (especially rationality), can be traced back to Thales, Xenophanes of Colophon (570 - 480 B.C.), Anaxagoras, Pericles (c. 495 - 429 B.C.), Protagoras, Democritus and the historian Thucydides (c. 460 - 375 B.C.). These early Greek thinkers were all instrumental in the move away from a spiritual morality based on the supernatural, and the development of a more humanistic freethought (the view that beliefs should be formed on the basis of science and logic, and not be influenced by emotion, authority, tradition or dogma).