Poetry is a form of literary art which uses aesthetic and rhythmic qualities of language to evoke meanings in addition to, or in place of, prosaic ostensible meaning. Poetry has traditionally been distinguished from prose by its being set in verse; prose is cast in sentences, poetry in lines; the syntax of prose is dictated by meaning, whereas that of poetry is held across meter or the visual aspects of the poem. Prior to the 19th century, poetry was commonly understood to be something set in metrical lines; accordingly, in 1658 a definition of poetry is "any kind of subject consisting of Rhythm or Verses".
Possibly as a result of Aristotle's influence (his Poetics), "poetry" before the 19th century was usually less a technical designation for verse than a normative category of fictive or rhetorical art. As a form it may pre-date literacy, with the earliest works being composed within and sustained by an oral tradition; hence it constitutes the earliest example of literature. Prose is a form of language that possesses ordinary syntax and natural speech rather than rhythmic structure; in which regard, along with its measurement in sentences rather than lines, it differs from poetry. On the historical development of prose, Richard Graff notes that "[In the case of Ancient Greece] recent scholarship has emphasized the fact that formal prose was a comparatively late development, an "invention" properly associated with the classical period".