Anacrusis: Upbeat in Poetry, Music

The word anacrusis, with the basic meaning of "upbeat," has important uses in both poetry and music.

Etymology
Anacrusis, which entered English in the 19th century, is a New Latin word derived from Greek anakrousis ("beginning of a song"). The Greek noun is based on the verb anakrouein ("to begin a song"), from ana- ("up, upward") plus krouein ("to strike, beat"). The English plural is anacruses.

Anacrusis in Poetry
In poetry, an anacrusis is one or more unaccented extra syllables at the beginning of a verse (line) before the regular rhythm, or metrical pattern, of the line begins. An early user of the literary term defined it as "an upward beat" (1844, Oxford English Dictionary).

Traditionally, poetic meter, or rhythmic pattern, is described in two ways: the foot and the line.

A foot is a small rhythmic unit consisting of any one of various combinations of two or three stressed (/) and unstressed (U) syllables. For example, a foot with a stressed syllable (/) followed by an unstressed syllable (U) is called a trochee, or a trochaic foot, indicated like this: / U.

A line is classified in terms of the number of feet it contains. For example, a line with three feet is known as trimeter.

Therefore, a line consisting of three trochaic feet is called trochaic trimeter. The following chart shows a regular trochaic trimeter verse (a horizontal line separates each foot): / U | / U | / U.

Here, however, is a trochaic trimeter line preceded by an anacrusis, giving the line an "upbeat": U / U | / U | / U.

Anacrusis in Music
In music, an anacrusis is one or several notes before the first complete measure of a phrase and thus before the first metrically accented beat. It is also called an upbeat or a pickup.

An anacrusis characteristically gives a sense of fluency and movement between phrases. That sense is often missing when a phrase begins on a downbeat. Too many consecutive phrases beginning on a downbeat can produce rhythmic squareness, heaviness, or predictability.

However, even when a principal phrase begins with a downbeat, composers can prevent metric squareness by creating anacruses between subsequent phrases. The procedure is fairly simple. When the final measure of a phrase is reached, melodic and rhythmic continuity, either thematic or merely transitional, in that measure can create an anacrusis effect into the first measure of the next phrase.

A musical anacrusis is not always rhythmically weak. It can be accented in various ways, as by using dynamic marks to make it louder than the subsequent downbeat and/or by tying an upbeat note (or notes of a chord) across the bar line to the first beat of the next measure, thus creating a syncopation, or momentary contradiction in the rhythmic flow of the established meter. In these cases, the upbeat, or anacrusis, will be relatively strong, and the downbeat will be relatively weak.

In string-instrument playing, an anacrusis is usually associated with the up-bow, a stroke in which the bow is moved across the strings from the tip of the bow to the heel. The downbeat usually suggests the down-bow, a stroke from the heel to the tip.