A hemistich is a half-line of verse, followed and preceded by a caesura

Caesura

thumb|100px|An example of a caesura in modern western music notation.In meter, a caesura is a complete pause in a line of poetry or in a musical composition. The plural form of caesura is caesuras or caesurae...

, that makes up a single overall prosodic or verse unit. In Classical poetry, the hemistich is generally confined to drama. In Greek tragedy

Tragedy

Tragedy is a form of art based on human suffering that offers its audience pleasure. While most cultures have developed forms that provoke this paradoxical response, tragedy refers to a specific tradition of drama that has played a unique and important role historically in the self-definition of...

, characters exchanging clipped dialogue to suggest rapidity and drama would speak in hemistichs (in hemistichomythia). The Roman poet Virgil

Virgil

Publius Vergilius Maro, usually called Virgil or Vergil in English , was an ancient Roman poet of the Augustan period. He is known for three major works of Latin literature, the Eclogues , the Georgics, and the epic Aeneid...

 employed hemistichs in the Aeneid

Aeneid

The Aeneid is a Latin epic poem, written by Virgil between 29 and 19 BC, that tells the legendary story of Aeneas, a Trojan who travelled to Italy, where he became the ancestor of the Romans. It is composed of roughly 10,000 lines in dactylic hexameter...

to indicate great duress in his characters, where they were incapable of forming complete lines due to emotional or physical pain.

In neo-classicism, the hemistich was frowned upon (e.g. by John Dryden

John Dryden

John Dryden was an influential English poet, literary critic, translator, and playwright who dominated the literary life of Restoration England to such a point that the period came to be known in literary circles as the Age of Dryden.Walter Scott called him "Glorious John." He was made Poet...

), but Germanic poetry employed the hemistich as a basic component of verse. In Old English and Old Norse

Old Norse

Old Norse is a North Germanic language that was spoken by inhabitants of Scandinavia and inhabitants of their overseas settlements during the Viking Age, until about 1300....

 poetry, each line of alliterative verse

Alliterative verse

In prosody, alliterative verse is a form of verse that uses alliteration as the principal structuring device to unify lines of poetry, as opposed to other devices such as rhyme. The most commonly studied traditions of alliterative verse are those found in the oldest literature of many Germanic...

 was divided into an "a-verse" and "b-verse" hemistich with a strong caesura between. In Beowulf

Beowulf

Beowulf , but modern scholars agree in naming it after the hero whose life is its subject." of an Old English heroic epic poem consisting of 3182 alliterative long lines, set in Scandinavia, commonly cited as one of the most important works of Anglo-Saxon literature.It survives in a single...

, there are only five basic types of hemistich, with some used only as initial hemistichs and some only as secondary hemistichs. Furthermore, Middle English

Middle English

Middle English is the stage in the history of the English language during the High and Late Middle Ages, or roughly during the four centuries between the late 11th and the late 15th century....

 poetry also employed the hemistich as a coherent unit of verse, with both the Pearl Poet

Pearl Poet

The "Pearl Poet", or the "Gawain Poet", is the name given to the author of Pearl, an alliterative poem written in 14th-century Middle English. Its author appears also to have written the poems Sir Gawain and the Green Knight, Patience, and Cleanness; some scholars suggest the author may also have...

 and Layamon

Layamon

Layamon or Laghamon (ˈlaɣamon; in American English often modernised as ; ), occasionally written Lawman, was a poet of the early 13th century and author of the Brut, a notable English poem of the 12th century that was the first English language work to discuss the legends of Arthur and the...

using a regularized set of principles for which metrical (as well as alliterative) forms were allowed in which hemistich position.