In poetics

Poetics

Aristotle's Poetics is the earliest-surviving work of dramatic theory and the first extant philosophical treatise to focus on literary theory...

, closed couplets are two line units of verse that do not extend their sense beyond the line's end. Furthermore, the lines are usually rhymed. When the lines are in iambic pentameter

Iambic pentameter

Iambic pentameter is a commonly used metrical line in traditional verse and verse drama. The term describes the particular rhythm that the words establish in that line. That rhythm is measured in small groups of syllables; these small groups of syllables are called "feet"...

, they are referred to as heroic verse

Heroic verse

Heroic verse consists of the rhymed iambic line or heroic couplet. The term is used in English exclusively.In ancient literature, heroic verse was synonymous with the dactylic hexameter. It was in this measure that those typically heroic poems, the Iliad and Odyssey and the Aeneid were written...

. However, Samuel Butler also used closed couplets in his iambic tetrameter Hudibrastic

Hudibras

Hudibras is an English mock heroic narrative poem from the 17th century written by Samuel Butler.-Purpose:The work is a satirical polemic upon Roundheads, Puritans, Presbyterians and many of the other factions involved in the English Civil War...

 verse.

"True wit is nature to advantage dressed

What oft was thought, but ne'er so well express'd"

is an example of the closed couplet in heroic verse from Alexander Pope

Alexander Pope

Alexander Pope was an 18th-century English poet, best known for his satirical verse and for his translation of Homer. He is the third-most frequently quoted writer in The Oxford Dictionary of Quotations, after Shakespeare and Tennyson...

's Essay on Criticism.