Parallel construction is a device, which may be encountered not so much in the sentence. The necessary condition in parallel construction is identical or, similar, syntactical structure in two or more, sentences or parts of a sentence, as in:
E.g. "There were, ..., real silver spoons to stir he tea with, and real china cups to drink it out of, and plates of the same to hold the cakes and toast in. " (Dickens)
Parallel constructions are often backed up by repetition of is (lexical repetition) and conjunctions and prepositions polysyndeton). Pure parallel construction, however, does not depend on any other kind of repetition but the repetition of the syntactical design of the sentence.
Parallel constructions may be partial or complete. Partial parallel arrangement is the repetition of some parts of successive sentences or clauses as in:
"It is the mob that labours in your fields and serve in your houses - that man your navy and recruit your army, - that have enabled you to defy all the world, and can also defy you when neglect and calamity have driven them to despair." (Byron)
The attributive clauses here all begin with the subordinate conjunction that which is followed by a verb in the same tense form, except the last (have enabled). The verbs however are followed either by adverbial modifiers of place (in your fields, in your houses) or by direct objects (your navy, your army).
The third attributive clause is not built on the pattern of the first two, although it preserves the parallel structure in general (that + verb predicate + object), while the fourth has broken away entirely. Complete parallel arrangement, also called balance, maintains the principle of identical structures throughout the corresponding sentences, as in: "The seeds ye sow - another reaps, The robes ye weave - another wears, The arms ye forget- another bears." (P. B. Shelley)
Parallel construction is most frequently used in enumera¬tion, antithesis and in climax, thus consolidating the general effect achieved by these stylistic devices.
There are two main functions of parallel construction: semantic and structural. On the one hand a parallel arrangement suggests equal semantic significance of the component parts, on the other hand, it gives a rhythmical design to these component parts, which makes itself most keenly felt in balanced" constructions. Parallel construction is used in different styles of writing with slightly different functions. When used in the matter-of-fact styles it carries, in the main, the idea of semantic equality of the parts, as in scientific prose, where the logical principle of arranging ideas predominates. In the belles-lettres style parallel construction carries an emotive function. That is why it is mainly used as a technical means in building up other stylistic devices, in particular antithesis and climax. It is natural that parallel construction should very frequently be used in poetical structures. Alternation of similar units being the basic principle of verse, similarity in longer units - i.e. in the stanza, is to be expected.