These are the opening words of Aristotle's Poetics, generally recognized as the most influential work in the history of Western European drama and poetic theory since the Renaissance. The initial statement of the scope of the inquiry is a formidable one; but a reader coming to it for the first time might well be forgiven for concluding that it promises far more than it achieves. Is it possible, he might ask, that all this is contained in a slim volume occupying no more than 47 pages in the Oxford Classical Text and 45 in the Penguin translation? Reading further, he might become even more disillusioned: what he discovers is that, after a very brief and perfunctory introduction on poetry as a form of mimesis or artistic representation, Aristotle limits himself to a discussion of tragedy, a cursory treatment of epic, and a few passing references to comedy, and that, even in the case of tragedy, by far the major part of the argument is devoted to an examination of plot. Can this really be the work which excited scholars in the Renaissance, inspired Milton to write Samson Agonistes, an Aristotelian drama if there ever was one, provided the structural pattern and dramatic conventions for the plays of Racine and Corneille, gave Fielding the principles on which he based his Tom Jones, influenced Goethe and Lessing and, through Lessing, Coleridge, and has won the attention and admiration of critics writing in English from James Harris at the end of the eighteenth century to Richard MacKeon in the second half of the twentieth? And, if so, why?