Parallelism operates both on the level of the sentence and of the discourse. (Sometimes this distinction is made in terms of the microlevel and macrolevel.)The primary value of grammatical parallelism is that it signals logical coordination. Parallel structure lets a writer express coordinate ideas in like ways.

Grammatical parallelism is signaled by the coordinating conjunctions:

and but nor or

for so yet

And by the correlative conjunctions:

both -- and either -- or neither -- nor not only -- but also

The coordinating conjunction, "nor," connects two nouns.

"This note was a promise that all men would be guaranteed the unalienable rights of life, liberty, and the pursuit of happiness" (431).

Here, the coordinate elements are the three compliments of the direct object, "unalienable rights." The first two are simple nouns, while the third is a noun with a prepositional phrase as a modifer.

"It would be fatal for the nation to overlook the urgency of the moment and to underestimate the determination of the Negro" (431).

Here, the coordinating conjunction "and" connects the two infinitive phrases with their objects and the prepositonal modifiers of the objects.

"This sweltering summer of the Negro's ligitimate discontent will not pass until there is an invigorating autumn of freedom and equality" (431).

This is a complex sentence (It has an independent clause and a dependent clause introduced by "until."). The parallelism here balances the contrasting images of the metaphor on coordinate grammatical structures (the subject of each clause followed by its prepositional modifier). Note that the word "there" is called an "expletive" and merely introduces the clause, having no grammatical function. The real subject of the clause is invigorating autumn.

"The marvelous new militancy which has engulfed the Negro community must not lead us to a distrust of all white people, for many of our white brothers, as evidenced by their presence here today, have come to realize that their destiny is tied up with our destiny and their freedom is inextricably bound to our freedom" (432).

In this sentence the parallel elements are the two noun clauses that are the objects of the infinitive "to realize."

Parallelism enables writers to maintain control of their sentences as they elaborates ideas. This is illustrated in the Christensen and Christensen analysis of multiple level sentences. Here are some examples they give:

1. The roof was the color of weather,
     2. white with the sun, (Adjective Phrase)
     2. gray with the rain, (Adjective Phrase)
     2. deep gray with the moon, (Adjective Phrase)
     2. rose with the sunset. (Adjective Phrase)
          Elizabeth Madox Roberts
                    (Christensen and Christensen 47)

This is a two level sentence. Level one is the base clause, and level two contains the four modifiers of that clause. The modifiers are gramatically parallel, each being an adjactive phrase.

1. A green frog watched me put on my shoes,
          2. I sitting on a boulder,(Absolute)
          2. he sitting in the pond, (Absolute)
                    3. his fingers resting upon its edge, (Absolute)
                    3. his golden eyes upon me. (Absolute)
                    (Christensen and Chrestensen 32)

In the sentence above, the base clause is again designated level 1. On level two there are two absolutes; the first of these describes the "me" and the second the frog. On the third level, both of absolutes describe the frog's vigilant posture.

1. So once more he stood on dry land . . .
          2. he and the woman standing on the empty levee, (Absolute)
                    3. the sleeping child wrapped in the faded tunic (Absolute)
                    and
                    3. the grapevine painter still wrapped about the convict's wrist, (Absolute)
                    3. watching the steamboat . . . crawl onward up the platter-like reach of vacant                                     water, (Verb Phrase)
                              4. burnished more and more to copper, (Verb Phrase)
                              4. its trailing smoke roiling in slow copper-edged gouts, (Absolute)
                                        5. thinning out along the water, (Verb Phrase)
                                        5. fading, (Verb Phrase)
                                        5. slinking away across the vast serene desolation, (Verb                                              Phrase)
                                        4. the boat growing smaller and smaller until it did not seem to                                              crawl at all but to stand stationary in the airy substanceless                                              sunset, (Absolute)
                                                 dissolving into nothing like a pellet of floating mud. (Verb                                                       Phrase)          William Faulkner
                                                  (Christensen and Christensen 35)

This example from William Faulkner is a much more complex sentence with more levels and with several kinds of modifiers. In contrast to the previous examples where modifiers on the same level were of the same kind and illustrated a strict grammatical parallelism, Faulkner's sentence violates this principle. For example, in the first group of third level modifiers, Faulkner uses both absolutes and a verb phrase. Among the fouth level modifiers, he again mixes the two structures.

Two factors are at work here. First, the absolutes and verb phrases belong to the same class of grammatical elements -- they are both modifiers of nouns. So although they differ in grammatical form, they are alike in grammatical function. Second, the modifying elements in each group are logically parallel (or coordinate) because they modify the same sentence element on the preceding level. In the language of dependency analysis(Deese 1984), the modifers are subordinate to and therefore dependent upon the higher levels of the sentence for their interpretation.

The kinds of proof a public speaker may provide fall into four categories: logos, ethos, pathos, and mythos.

The writer can discuss each of these terms in a separate section of the essay. A topic sentence that focuses on one of the terms will introduce each section. If the topic sentences are written in the same way, then the repetition of form will emphasize the the coordinate status of the four sections. Here is how the sentences might look:

The first type of proof suggested by Aristotle in his Rhetoric is logos that emphasizes rational evidence.

Another type of proof suggested by Aristotle is pathos that emphasizes proof based on motives or emotions.

A third type of proof suggested by Aristotle is ethos that emphasizes proof based on the personality, character, and reputation of the speaker.

In addition to the three types of proof suggested by Aristotle, there is a fourth called mythos that emphasizes those frequently told stories that express the traditions, identity, and values of a group(Osborn and Osborn 379-380).

Students sometimes complain that the repetition illustrated sounds simple minded. However, the topic sentences will not be listed in an essay as they are here; indeed, they may be separated by several paragraphs or pages, and the more intervening material, the more valuable they become, not only as signals that a new part of the discussion is about to begin, but also as signals that each part is related to the main idea as well as to the preceding sections. The longer the discourse, and the denser the reading matter, the more the reader needs these topic sentences.

A construction can have grammatical parallelism without a concomitant logical parallelism.