In rhetoric, parallelism means giving two or more parts of the sentences a similar form so as to give the whole a definite pattern.
Parallelisms of various sorts are the chief rhetorical device of Biblical poetry  and in the poetry of many cultures around the world, particularly in oral traditions. Robert Lowth coined the term "parallelismus membrorum (parallelism of members, i.e. poetic lines) in his 1788 book, Lectures on the Sacred Poetry of the Hebrew Nation. Roman Jakobson pioneered the secular study of parallelism in poetic-linguistic traditions around the world, including his own Russian tradition.
In addition, Chinese poetry uses parallelism in its first form. In a parallel couplet not only must the content, the parts of speech, the mythological and historico- geographical allusions, be all separately matched and balanced, but most of the tones must also be paired reciprocally. Even tones are conjoined with inflected ones, and vice versa.
Parallelisms in artistic speech are common in some languages of Mesoamerica, such as Nahuatl (Aztec). It has also been observed in a language of Indonesia (that Fox imprecisely referred to as "Rotinese") and Navajo. Other research has found parallelisms in the languages of the Ural-Altaic area (including Finnish-Karelian folk poetry and the epics and songs of the Turkic and Mongolian peoples) and Toda, suggesting wider distribution among Dravidian languages.
"We charge him with having broken his coronation-oath - and we are told that he kept his marriage-vow! We accuse him of having given up his people to the merciless inflictions of the most hard-hearted of prelates - and the defense is that he took his little son on his knee and kissed him. We censure him for having violated the Petition of Right - and we are informed that he was accustomed to hear prayers at six o'clock in the morning." (Macaulay)
"The inherent vice of capitalism is the unequal sharing of blessing; the inherent virtue of socialism is the equal sharing of miseries." (Churchill)
"But let judgment run down as waters, and righteousness as a mighty stream." (Amos)
"What you see is what you get." English proverb
See also 
- "Parallelism". Catholic Encyclopedia. New York: Robert Appleton Company. 1913.Online version of article
- Casanowicz, I. M. "PARALLELISM IN HEBREW POETRY". JewishEncyclopedia.com. Retrieved December 7, 2011.
- p. 216.James J. Fox. 1971. Semantic Parallelism in Rotinese Ritual Language. Bijdragen tot de Taal-, Land- en Volkenkunde Deel 127, 2de Afl., pp. 215-255.
- Jakobson, Roman. 1987. "The Poetry of Grammar and the Grammar of Poetry." In Language in Literature. K. Pomorska and S. Rudy, eds. Pp. 121-144. Cambridge, MA: The Belnap Press of Harvard University.
- Chinese Poetic Literature China Virtual Tours - ChinaVista services - 1996-2010.
- William Bright. 1990. "With one lip, with two lips": Parallelism in Nahuatl. Language 66.3:437-452.
- James J. Fox. 1971. Semantic Parallelism in Rotinese Ritual Language. Bijdragen tot de Taal-, Land- en Volkenkunde Deel 127, 2de Afl., pp. 215-255.
- Coyote Poems: Navajo Poetry, Intertextuality, and Language Choice. Anthony K. Webster. 2004. Coyote Poems: Navajo Poetry, Intertextuality, and Language Choice. American Indian Culture and Research Journal 28.4:69-91.