Ars Poetica

Ars Poetica is a term meaning "The Art of Poetry" or "On the Nature of Poetry". Very Early examples of Artes Poeticae by Aristotle and Horace have survived and many other poems bear the same name. Horácio Horace's Ars Poetica (also known as "The Art of Poetry," Epistula Ad Pisones, or Letters to Piso), published c. 18 BC, was a treatise on poetics. It was first translated into English by Thomas Drant. Three quotations in particular are associated with the work:

• "in medias res," or "into the middle of things." This describes a popular narrative technique that appears frequently in ancient epics and remains popular
• "bonus dormitat Homerus" or "good Homer nods"; an indication that even the most skilled poet can make continuity errors
• "ut pictura poesis," or "as is painting so is poetry," by which Horace meant that poetry, in its widest sense meaning "imaginative texts," merits the same careful interpretation that was in his day reserved for painting.

The latter two phrases occur one after the other near the end of the treatise.

The work is also key for its discussion of the principle of decorum, the use of appropriate vocabulary and diction in each style of writing, and for Horace's criticisms of purple prose.

In verse 191, Horace warns against deus ex machina, the practice of resolving a convoluted plot by having an Olympian god appear and set things right. Horace writes "Nec deus intersit, nisi dignus vindice nodus": "That a god not intervene, unless a knot show up that be worthy of such an untangler".