Essay of Dramatic Poesy by John Dryden was published in 1668. It was probably written during the plague year of 1666. Dryden takes up the subject that Philip Sidney had set forth in his Defence of Poesie (1580) and attempts to justify drama as a legitimate form of "poetry" comparable to the epic, as well as defend English drama against that of the ancients and the French.
The treatise is a dialogue between four speakers: Eugenius, Crites, Lisideius, and Neander. The four speakers represented, respectively Charles Sackville ( Lord Buchhurst and later sixth Earl of Dorset), Sir Robert Howard [playwright and Dryden's brother-in-law], Sir Charles Sedley ( Edward Malone identified him as Lisideius) and Dryden himself (neander means "new man" and implies that Dryden, as a respected member of the gentry class, is entitled to join in this dialogue on an equal footing with the three older men who are his social superiors). On the day that the English fleet encounters the Dutch at sea near the mouth of the Thames, the four friends take a barge downriver towards the noise from the battle. Rightly concluding, as the noise subsides, that the English have triumphed, they order the bargeman to row them back upriver as they begin a dialogue on the advances made by modern civilization. They agree to measure progress by comparing ancient arts with modern, focusing specifically on the art of drama (or "dramatic poesy"). The four men debate a series of three topics: (1) the relative merit of classical drama (upheld by Crites) vs. modern drama (championed by Eugenius); (2) whether French drama, as Lisideius maintains, is better than English drama (supported by Neander, who famously calls Shakespeare "the greatest soul, ancient or modern"); and (3) whether plays in rhyme are an improvement upon blank verse drama--a proposition that Neander, despite having defended the Elizabethans, now advances against the skeptical Crites (who also switches from his original position and defends the blank verse tradition of Elizabethan drama). Invoking the so-called unities from Aristotle's Poetics (as interpreted by Italian and refined by French scholars over the last century), the four speakers discuss what makes a play "a just and lively imitation" of human nature in action. This definition of a play, supplied by Lisideius/Orrery (whose rhymed plays had dazzled the court and were a model for the new drama), gives the debaters a versatile and richly ambiguous touchstone. To Crites' argument that the plots of classical drama are more "just," Eugenius can retort that modern plots are more "lively" thanks to their variety. Lisideius shows that the French plots carefully preserve Aristotle's unities of action, place, and time; Neander replies that English dramatists like Ben Jonson also kept the unities when they wanted to, but that they preferred to develop character and motive. Even Neander's final argument with Crites over whether rhyme is suitable in drama depends on Aristotle's Poetics: Neander says that Aristotle demands a verbally artful ("lively") imitation of nature, while Crites thinks that dramatic imitation ceases to be "just" when it departs from ordinary speech--i.e. prose or blank verse. A year later, the two brothers-in-law quarreled publicly over this third topic. See Dryden's "Defense of An Essay of Dramatic Poesy" (1669), where Dryden tries to persuade the rather literal-minded Howard that audiences expect a play to be an imitation of nature, not a surrogate for nature itself.