Introduced by Francis Fergusson, the "Poetics," written in the fourth century B.C., is still an essential study of the art of drama, indeed the most fundamental one we have. It has been used by both playwrights and theorists of many periods, and interpreted, in the course of its two thousand years of life, in various ways. The literature which has accumulated around it is, as Mr. Fergusson points out, "full of disputes so erudite that the nonspecialist can only look on in respectful silence." But the "Poetics "itself is still with us, in all its suggestiveness, for the modern reader to make use of in his turn and for his own purposes. Francis Fergusson's lucid, informative, and entertaining Introduction will prove invaluable to anyone who wishes to understand and appreciate the" Poetics." Using Sophocles' "Oedipus Rex," as Aristotle did, to illustrate his analysis, Mr. Fergusson pints out that Aristotle did not lay down strict rules, as is often thought: "The "Poetics,"" he says, "is much more like a cookbook than it is like a textbook of elementary engineering." Read in this way, it is an essential guide not only to Sophoclean tragedy, but to the work of so modern a playwright as Bertolt Brecht, who considered his own "epic drama" the first non-Aristotelian form.