As both a literary genre and a view of life, tragedy has from the very beginning spurred a dialogue between poetry and philosophy. Plato famously banned tragedians from his ideal community because he believed that their representations of vicious behavior could deform minds. Aristotle set out to answer Plato's objections, arguing that fiction offers a faithful image of the truth and that it promotes emotional health through the mechanism of catharsis. Aristotle's definition of tragedy actually had its greatest impact not on Greek tragedy itself but on later Latin literature, beginning with the tragedies of the Roman poet and Stoic philosopher Seneca (4 BC - AD 65). Scholarship over the last fifty years, however, has increasingly sought to identify in Seneca's prose writings a Platonic poetics which is antagonistic toward tragedy and which might therefore explain why Seneca's plays seem so often to present the failure of Stoicism. As Gregory Staley argues in this book, when Senecan tragedy fails to stage virtue we should see in this not the failure of Stoicism but a Stoic conception of tragedy as the right vehicle for imaging Seneca's familiar world of madmen and fools. Senecan tragedy enacts Aristotle's conception of the genre as a vivid image of the truth and treats tragedy as a natural venue in which to explore the human soul. Staley's reading of Seneca's plays draws on current scholarship about Stoicism as well as on the writings of Renaissance authors like Sir Philip Sidney, who borrowed from Seneca the word "idea" to designate what we would now label as a "theory" of tragedy. Seneca and the Idea of Tragedy will appeal broadly to students and scholars of classics, ancient philosophy, and English literature.
This book is frustrating because it gets so close to making interesting points, but consistently never gets all the way there. It also several times mentions interesting people or idea that it never gets around to fully discussing -- Nicholas Trevet and the 13/14th Century recovery of Seneca's tragedies, for instance, or a thorough linkage of Senecan poetics with humoural theory.
I think I feel that way because the main topic of the book is the period well before my own, and what are essentially tangential asides to the author's thesis are more vital to my own studies. (Although to be fair, for someone whose main thesis is not Phillip Sidney, Sidney shows up a lot.)
The closer it adheres to a Classical background, the better it is. Staley's thesis describes a specifically Roman, specifically Stoic framework for understanding Seneca's tragedies, more or less based on Aristotle's Poetics, and strongly informed on this philosophical traditions between Seneca and Aristotle.
I'd like to have seen further development with the idea, with a discussion that ties the specific ideas he uses with later traditions. He does this to a limited degree with Sidney and a few earlier Continental Renaissance critics, but with the huge influence of Seneca on the drama of the Renaissance, there's still a lot left to say.