What contribution did Aristotle make to theatre in his Poetics?
Aristotle's Poetics is a work of literary criticism that attempted to understand the nature and effect of classical Greek drama and its role in the polis (city-state). As a descriptive work, it did not contribute to theater itself in antiquity and the middle ages, but rather to how students and literary critics analyzed plays. The descriptions in Aristotle's Poetics were very much limited to his time and place. He assumed that plays were either tragedies or comedies, rather than mixed genres, that a play used a maximum of three actors playing all roles and a chorus, that plays were written in verse, and that tragedies held up noble characters as models for emulation and that comedy made fun of ignoble characters. As the New Comedy of Menander developed after Aristotle wrote the Poetics, the possibility of domestic or romantic drama was not included in the Poetics.
The Poetics did not really become used as a standard or guideline for how to compose plays until the "neoclassical" movement in the late seventeenth and eighteenth centuries, when neo-Aristotelian notions such as the "three unities" and a standard plot structure informed the works of such playwrights as Racine.