Why is Of Dramatick Poesie considered important in the history of literary criticism?

John Dryden’s Of Dramatick Poesie, an Essay (1668) is widely regarded as the first substantial piece of modern dramatic criticism in English. Its importance in the history of literary criticism stems from several key factors:12

• Innovative Methodology: Unlike the rigid, dogmatic approaches of many of his contemporaries, Dryden’s tone is exploratory and undogmatic. He employs a leisurely discussion between four fictionalized characters, which allows him to argue multiple sides of a question and break down conventional oppositions between ancient and modern, French and English, and Elizabethan and Restoration drama.12
• Defense of English Drama: The work serves as a sophisticated defense of English drama against the champions of Classical and Neoclassical French theatre. Dryden approaches the "rules" of drama—such as the unities of time, place, and action—with refreshing honesty, questioning their necessity and defending practices like Shakespeare’s mixture of comedy and tragedy.23
• Analytical Depth: It contains the first extended analysis of an English play, specifically his discussion of Ben Jonson’s Epicoene; or, The Silent Woman.1

By combining general principles with specific analysis in a gracefully informal style, Dryden established himself as the "father of English criticism," setting a precedent for future critical discourse.12