A student of Socrates, Plato (427-347 BC) introduced a dualistic view of the world. Ideas are separate from matter and exist in their own world; matter is an imperfect copy of that reality.
Although Socrates never founded a school, Plato’s Academy offered courses in astronomy, mathematics, philosophy and political science. Differentiating between perfect ideas and imperfect matter, Plato introduced a dualistic view of the world. Ideas are separate from matter and exist in their own world. What we see are imperfect representations of those perfect forms. For Plato, knowledge is reminiscent (existing in the soul before birth), and the psyche is the source of thinking and moral actions.
Plato held that ideas are reality but that matter is an imperfect copy of that reality. For Plato the Form (the general abstraction of the principle) was more important than material example. The Form of circularity is good and pure but a drawn circle is only an approximation of that ideal. Obviously, art would not be highly valued by Plato because it was an imperfect copy of an imperfect copy of reality.
Plato was a dualist, in the sense that he separated ideas (which were good) from matter (which was at worse evil and at best imperfect). In his 35 dialogues, Plato describes the search for wisdom. Ultimately, he concludes that the essence of people (the psyche) are made of three parts: the rational, the will and the appetites. Education raised people from lowly appetites to the use of will and ultimately to the highest human achievement – philosophy. Naturally, Plato suggests that society should be composed of three classes: the philosopher-kings, the military and the merchants.
Although Plato allowed that some knowledge may exist in the soul prior to birth (which he called reminiscence), his emphasis was on learned, infallible knowledge. For Plato, bad behavior was due to the lack of knowledge. He rejected the empiricism of direct observation because is a derived experience and was merely opinion. In contrast, knowledge brings justice, light, and reason.