Tragedy (Ancient Greek: τραγῳδία, tragōidia, etymology uncertain. previous idea: "he-goat-song", but this theory has been refuted by Walter Burkert) is a form of art based on human suffering that offers its audience pleasure. While most cultures have developed forms that provoke this paradoxical response, tragedy refers to a specific tradition of drama that has played a unique and important role historically in the self-definition of Western civilization. That tradition has been multiple and discontinuous, yet the term has often been used to invoke a powerful effect of cultural identity and historical continuity—"the Greeks and the Elizabethans, in one cultural form; Hellenes and Christians, in a common activity," as Williams puts it. From its obscure origins in the theatres of Athens 2500 years ago, from which there survives only a fraction of the work of Aeschylus, Sophocles and Euripides, through its singular articulations in the works of Shakespeare, Lope de Vega, Racine, or Schiller, to the more recent naturalistic tragedy of Strindberg, Beckett's modernist meditations on death, loss and suffering, or Müller's postmodernist reworkings of the tragic canon, tragedy has remained an important site of cultural experimentation, negotiation, struggle, and change. A long line of philosophers—which includes Plato, Aristotle, Saint Augustine, Voltaire, Hume, Diderot, Hegel, Schopenhauer, Kierkegaard, Nietzsche, Freud, Benjamin, Camus, Lacan and Deleuze—have analysed, speculated upon and criticised the tragic form. In the wake of Aristotle's Poetics (335 BCE), tragedy has been used to make genre distinctions, whether at the scale of poetry in general, where the tragic divides against epic and lyric, or at the scale of the drama, where tragedy is opposed to comedy. In the modern era, tragedy has also been defined against drama, melodrama, the tragicomic and epic theatre.