<P> In contrast to Plato, Aristotle discusses the Forms of Good in critical terms several times in both of his major surviving ethical works, the Eudemian and Nicomachean Ethics . Aristotle argues that Plato's Form of the Good does not apply to the physical world, for Plato does not assign "goodness" to anything in the existing world . Because Plato's Form of the Good does not explain events in the physical world, humans have no reason to believe that the Form of the Good exists and the Form of the Good is thereby irrelevant to human ethics . </P> <P> Plato and Aristotle were not the first contributors in ancient Greece to the study of the' good' and discussion preceding them can be found among the pre-Socratic philosophers . In Western civilisation, the basic meanings of κακός and ἀγαθός are "bad, cowardly" and "good, brave, capable", and their absolute sense emerges only around 400 BC, with Pre-Socratic philosophy, in particular Democritus . Morality in this absolute sense solidifies in the dialogues of Plato, together with the emergence of monotheistic thought (notably in Euthyphro, which ponders the concept of piety (τὸ ὅσιον) as a moral absolute). The idea is further developed in Late Antiquity by Neoplatonists, Gnostics, and Church Fathers . </P> <P> Aside from ancient Greek studies of the' good', the eastern part of ancient Persia almost five thousand years ago a religious philosopher called Zoroaster simplified the pantheon of early Iranian gods into two opposing forces: Ahura Mazda (Illuminating Wisdom) and Angra Mainyu (Destructive Spirit) which were in conflict . </P> <P> For the western world, this idea developed into a religion which spawned many sects, some of which embraced an extreme dualistic belief that the material world should be shunned and the spiritual world should be embraced . Gnostic ideas influenced many ancient religions which teach that gnosis (variously interpreted as enlightenment, salvation, emancipation or' oneness with God') may be reached by practising philanthropy to the point of personal poverty, sexual abstinence (as far as possible for hearers, total for initiates) and diligently searching for wisdom by helping others . </P>

Where does the definition of good come from