There is also an implicit ethical theory in greek culture which preexisted philosophical reflection. The main ethical category for ancient greeks was arete or virtue, which meant a certain strenght or ability, or even force. The objective of a successful life was attaining doxa, or glory. Also an important concept in greek culture was that of hybris, trying to go beyond once possibilities (see Oedipus Rex). The literary sources of this folk ethical theories can be seen in Homer, greek tragedy and also Aesop's fables.
The first antecedent to an ethical theory are the dicta of the Seven Sages of Geek (the list changes, so they are not actually the same seven in every compilation) who suggested a measure in man's life according to nature (or "metron".)
Presocratics (the first philosophers, concerned above all by cosmology. some of them sometimes included in the Sages, like Thales made reflections in a similar fashion. Heraclitus thought that injustice appears only in the eyes of men, and that a divine perspective would show that everything is just. Pitagoras founded a sect in which a good reincarnation (see metempsicosis) was to be attianed through following certain cleannines practices (forbiddden foods) and knowledge about mathematics. However, not always presocratic philosopher's ethical opinions were connected to their physycal or metaphysical doctrine, like int he case of Democritus (already a contemporary of Socrates), proposed cheerfulness as the suprem goal of life, which is unrelated to his atomistic theory.
An important change came with the sofist movement, where persons of knowledge stopped being solitary sages and started resembling professional teachers. They travled from one polis to another, and were concerned above all by anthropological philosophical problems. Protagoras was a sophist and the first formulator of relativism in Western thought. By saying man is the measure of all things, he atacked the unchallenged notion of a fixed reality.
Socrates is a milestone in the history of ethics. He regarded of the first time areté as the rational part of the human soul/mind (both encompassed int he greek word psyché).
- Mauricio Beuchot, Etica - Giovanni Reale, History of philosophical and scientific thought - Peter Singer (comp.), Blackwell companion to ethics