For example, in Martin Luther King Jr.'s "I Have a Dream" speech, he uses parallel structure in the following sentence: "With this faith, we will be able to hew out of the mountain of despair a stone of hope." The repetition of the prepositional phrase "out of" creates a sense of rhythm, and it emphasizes the contrast between "despair" and "hope."
Another example of parallel structure is in the following sentence from the Declaration of Independence: "We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty, and the pursuit of Happiness." The repetition of the phrase "that all men are created equal" emphasizes the importance of this idea, and it sets the stage for the list of unalienable rights that follow.
Parallel structure is a powerful syntactic device that can be used to create a variety of effects in writing. It can help to emphasize important ideas, create a memorable effect, or add a sense of rhythm and balance to a piece of writing.