Both Aristotle's Poetics and Plato's Republic X address the question of the nature of poetry and its affect on its audience, taking audience as both the individual citizen and the polis as a whole. Both authors describe poetry as a form of verbal mimesis and distinguish tragedy and comedy as operating through pure mimesis from epic, which uses a mixture of diegesis and mimesis. The main difference is their attitudes towards poetry with Plato opposed to poetry on the grounds of its ontological status and Aristotle giving it qualified approval on ethical and political grounds. Plato opposes poetry because he considers it an imitation of the sensibilia which in turn are imitations of the forms. He also feels that the audience will imitate the violent and immoral acts found in much traditional epic. Aristotle sees poetry as useful in training the emotions, and providing examples of what to avoid as well as what to imitate.
The basic difference is, that Aristotle wrote his ''Poetics'' in response to, and to 'counter' Plato's view, that poetry is merely imitative and that it appeals to the irrational. Aristotle disagrees, he says that poetry--especially tragic poetry and tragedy is normal, it is also 'useful'. The tragic poet, he says, is not so much 'divinely inspired' as inspired/motivated by by a universal human desire/need to 'imitate' and in doing so, he is in fact imitating noble actions and deeds, which has a good, positive and 'civilising' effect for people. He calls this 'imitation' by the term ''Mimesis''; and that via watching this Mimetic experience, people are moved to certain high emotions and feelings and that they are thus purged inside, psychologically, by a process of 'Katharsis'.