Howard used the historical Duke of Lerma as inspiration for his tale. This is an image of the Duke.

Image from: http://www.abcgallery.com/R/rubens/rubens42.html

Dryden revises his work—a good practice! 255
He engages in a literary dialogue with the author of The Great Favorite, or the Duke of Lerma

He does not presume to champion the works of Aristotle and Horace; their arguments stand on their own

He proposes to defend the use of rhyme.
Rhyme is appropriate for serious subjects NOT because it is close to conversation, but because the use of it causes delight and the application of rhyme elevates a work

Dryden values the work of the poet; his audience seems to deem the players responsible for a play’s success 257

Ancients wrote in verse—Dryden argues for rhyme but he says that had the Ancients had it at their disposal, they would have used it as the modern authors do (since the 16th century)

He argues for attention to diction in poetry 259
Dryden says that poets should try to please; HOWEVER if a play does not please, that does not make it inferior as audiences cannot always be trusted to evaluate art

Opinions do not matter!
Poets should seek moral truth

Debate about the ancients versus the moderns 265
He argues for unities of place and time, but he is willing to accommodate diversion from the rules with scenery 266

We must suspend disbelief

Author of Duke of Lerma argues against unity of time 268

Poetic Terms from the OED:
 a. blank verse: verse without rime; esp. the iambic pentameter or unrimed heroic, the regular measure of
English dramatic and epic poetry, first used by the Earl of Surrey (died 1547).

Couplet
A pair of successive lines of verse, esp. when riming together and of the same length.