Aristotle's Poetics marks the beginning of literary criticism in Western Civilization, setting up principles of poetical and dramatic analysis, acting as a starting point for critics in the Renaissance and eighteenth century, and giving us a key to Greek art in general.
Plato, a name linked inextricably to philosophy, was a disciple of Socrates and wrote down many of his teachings. His book the Republic is a collection of social, political, and intellectual criticism. Ioncontains one of Western culture's most famous descriptions of poetic inspiration. Your own education has been shaped by Aristotle and Plato in ways you may not realize. When you studied "plots" and "characters" in elementary school you learned to read literature according to Aristotle's method. And Plato's ideas about art and artistic creativity are surprisingly relevent. One example: here is how Alanis Morrissette described her experience in writing songs (MTV, 8/20/95). "The songs in this set were all written in about fifteen minutes. Many times it felt as if it was all being channelled through us." Now, go read Ion.